Application of solar energy in the oil industry—Current status and future prospects

Renewable and Sustainable Energy Reviews 43 (2015) 296–314

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Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser

Application of solar energy in the oil industry—Current status and future prospects M. Absi Halabi b, A. Al-Qattan a,n, A. Al-Otaibi a a b

Energy and Building Research Center, Innovative Renewable Energy Program, Kuwait Institute for Scientific Research, PO Box 24885, Safat 13109, Kuwait Petroleum Research Center, Kuwait Institute for Scientific Research, PO Box 24885, Safat 13109, Kuwait

art ic l e i nf o

a b s t r a c t

Article history: Received 6 April 2014 Received in revised form 29 September 2014 Accepted 1 November 2014

The scope of this review is to highlight the potential contributions of solar energy in meeting the energy requirements of the oil and gas industry. It includes an assessment of the key factors that impact the world energy scene and the anticipated role of solar energy up to 2035. It appears that oil and gas will continue to play a dominant role in meeting world energy demand over the next two decades, accounting for nearly 60% of total primary energy, and reaching around 9960 Mtoe in 2035. The energy consumption of the oil and gas industries is nearly 10% of its total energy production and is expected to grow to a higher value with the growth of the share of unconventional oil and gas resources. The amounts of energy projected to be consumed by the oil and gas industry is estimated to be at least 39.4 EJ by 2035. The energy supply to meet the demand of the oil and gas industry is based mostly on hydrocarbon energy sources, which leads to high levels of ecological footprints. Solar energy utilization within the industry will reduce its fossil fuels consumption, and therefore reduce its ecological footprints. Specifically, solar energy will help the industry in meeting part of its energy requirements in locations where conventional fuels, such as natural gas, are limited. This paper reviews various efforts made in developing solar technologies to suit the oil and gas industry. It also shows that some upstream oil and gas industries have already utilized solar energy in demonstration field applications. The review concludes that the application of solar energy in the oil and gas industry presents a very good opportunity for future business of the renewable energy industry. These opportunities includes the use of photovoltaic and solar thermal technologies. & 2014 Elsevier Ltd. All rights reserved.

Keywords: Oil industry Petroleum Renewable Solar Fossil fuels

Contents 1.

2.

3.

4.

n

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 1.1. World energy supply and demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 1.1.1. Current and projected energy supply and demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 1.1.2. Availability of energy resources and security of the supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 1.1.3. Environmental impact of the oil and gas industry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 Energy consumption in the oil and gas industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 2.1. Energy consumption by the upstream oil and gas industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 2.2. Energy consumption by the downstream oil and gas industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 2.3. Factors impacting future energy consumption of oil and gas industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 Potentials of renewable energy in meeting the energy requirements of the oil industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 3.1. Providing electrical power to oil and gas production operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 3.2. Meeting oil production industry thermal energy needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 3.2.1. Low–medium temperature solar thermal applications: Process heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 3.2.2. High temperature solar heating applications in oil production: Enhanced oil recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 3.3. Solar applications in oil-field water desalination and treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 3.4. Applications of other renewable energy resources in oil production industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 Potential applications of renewable energy in downstream industry applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306

Corresponding author. E-mail addresses: [email protected] (M. Absi Halabi), [email protected] (A. Al-Qattan), [email protected] (A. Al-Otaibi).

http://dx.doi.org/10.1016/j.rser.2014.11.030 1364-0321/& 2014 Elsevier Ltd. All rights reserved.

M. Absi Halabi et al. / Renewable and Sustainable Energy Reviews 43 (2015) 296–314

4.1. Hydrogen and synthesis gas production. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Developments in photocatalytic reactors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Role of oil and gas companies in developing renewable energy technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. The economics of utilization of renewable energy in the oil and gas industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Future prospects of renewable energy in the oil and gas industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Introduction The global demand for energy over the next two decades is expected to increase by nearly 50%, reaching around 778 EJ by 2035 [1,2]. This increase in energy demand is expected to pose a major challenge for energy companies, particularly oil and gas companies, due to diminishing conventional oil reserves around the world, and increasing dependence on heavy crude oil, which requires significantly higher energy to produce and process. Hence, both the total energy consumption and the energy intensity, i.e., quantity of energy required per unit of oil or gas produced, are expected to increase. The oil and gas industry meets most of its energy demand from available hydrocarbon resources, therefore, environmental impact due to CO2 emissions during oil and gas production is expected to increase dramatically. Oil production and refining consume nearly 10% of the produced oil, which is equal to nearly 28 EJ in 2013. The largest share of this consumption is in the form of thermal energy required for processing oil and converting it into petroleum products. Abood et al. [3] pointed out that the industry must be more energy efficient and must also utilize renewable energy sources, whenever feasible. The industry should use its business and technology knowledge base to develop and promote sustainable energy products. The use of renewable energy resources by the industry will save significant amounts of oil and gas resources, freeing them to meet the energy demand for other applications locally or internationally, as well as reducing the environmental impact of the industry. This is in line with UNIDO’s [4] projections, which estimated that by 2050 the potential of renewable energy for industrial applications will reach around 21% of the final energy use in the manufacturing industry. The objective of this paper is to review the efforts made by the oil and gas industry over the past 40 years in adapting renewable

297

307 307 307 309 309 311 312 312

energy technologies and applying it to meet the energy demand of the industry. The paper also provides highlights of the role of the industry in developing renewable energy technologies and its attempt to integrate these technologies within the industry’s role as energy provider. The potential role of some advanced renewable energy applications, specifically solar energy technologies, which are currently in the R&D phase, in directly meeting the energy needs of selected high-temperature energy-intensive processes required for the petroleum refining industry is also being presented and its potential impact is discussed 1.1. World energy supply and demand It is important to acknowledge the dominant factors that currently impact the world energy scene. These factors are the following:


Projected energy demand.
Availability of energy resources and security of their supply.
Impact of energy resources on the environment.

1.1.1. Current and projected energy supply and demand Energy supply and demand for 2010 was pictorially summarized by the International Energy Agency (IEA) in its World Energy Outlook 2012 [2] (Fig. 1). The figure shows that total energy supply was around 532.5 EJ (12.72 Gtoe), out of which oil and gas supplies were around 53.8%, with most of the oil going into fossil fuels. The figure also shows that 34.25 EJ (818 Mtoe) or around 12.5% of input oil, gas, and coal were losses and consumed energy for producing fuels. For energy demand projection and according to the IEA’s reference scenario, which is based on a business-as-usual assumption,

Fig. 1. The global energy system (in million tons oil equivalent (Mtoe)) ([2], p. 62). (Notes: n Transformation of fossil fuels from primary energy into a form that can be used in the final consuming sectors. nn Includes losses and fuel consumed in oil and gas production, transformation losses and own use, generation lost or consumed in the process of electricity production, and transmission and distribution losses. 1 Mtoe ¼ 41.868 PJ).

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400

7

350

6

2007

Million Barrels/day

Million BOE/day

300 250 200 150

2030

5 4 3 2

100 1

50 0

0

Africa

2010 Oil

2020 Coal

Gas

Nuclear

Hydro

2035 Biomass & Other Renewables

Fig. 2. World energy demand (BOE: barrel oil equivalent ¼ 0.159 m3) [1].

the world’s annual energy demand is expected to grow to nearly 778 EJ (18.6 Gtoe) by 2035. These data also predict that non-hydro renewable energies will play a marginal role until 2035, meeting about 2% of the total energy demand [2]. However, one has to bear in mind that for this reference scenario, no additional political measures to mitigate GHG emissions were considered. The worldwide climate challenge must lead to some reductions in energy demand and GHG emissions. In order to achieve such reductions, increased efforts in energy efficiency and higher growth of renewables will be necessary. Similarly, ExxonMobil in its report “The Outlook for Energy— A View to 2040” [5], projected that the average annual growth of renewables, including hydro, will be around 7–8% in 2040, which is almost 3 times higher than the average annual growth of oil, gas or coal. Nevertheless, the contribution of renewables, other than hydro, to the total energy demand was projected to remain around 3 to 4% by 2040. Hence, ExxonMobil also concluded that most of the additional energy required to meet future world demand will be met through oil, gas, and coal. Similar projections are also reported by the Organization of the Petroleum Exporting Countries (OPEC) [1] and Shell International BV [6]. It is clear from these projections that if current global trends in energy use do not change, fossil fuels will remain the dominating source of primary energy over the next two decades. Fig. 2, which is based on data from OPEC Oil World Outlook, summarizes the projection for energy demand. The IEA expects that electricity generation will grow at a much faster rate than demand on total energy [2]. The IEA projections are similar to projections made by the US Energy Information Administration (EIA) [7]. According to the EIA, world electrical energy demand will grow at an annual rate of 3.1%, and the total additional power generation capacity that is required until 2035 is estimated at 5890 GW [7]. The factors contributing to the growth of electrical power demand include conventional factors, such as population growth and worldwide improvements in standards of living. However, the rapid growth of new, electricity-dependent technologies, such as electrical transportation systems, and communication and computer technologies are the main contributors to the accelerated growth. Most of this growth is expected to take place in regions with growing economies, such as China, India, and the Middle East. At least for the Middle East, where electricity generation is almost entirely dependent on oil and gas, energy transition options throughout the energy supply and demand chain must be assessed to develop scenarios for higher energy sustainability.

1.1.2. Availability of energy resources and security of the supply The second major issue shaping the future of the energy business is the availability and security of energy resources. Based on the total oil

Asia

Europe, Russia, CIS

Middle East

North America South America

Fig. 3. Projected development of heavy crude oil with API o 22 (1 barrel petroleum¼0.159 m3) [10].

and gas reserves and annual consumption at the end of 2011, the remaining lifetimes for conventional oil and gas are estimated by BP to be 54, and 64 years, respectively [8]. Most of the conventional oil and gas reserves are concentrated in the Middle East and Eurasia. To meet projected energy demand for many decades to come, the industry must resort to more advanced techniques of recovery from conventional reservoirs. Furthermore, to ensure continuous energy supplies beyond the above mentioned lifetimes, the oil industry has been active in developing technologies to tap the vast resources of unconventional hydrocarbons such as heavy oils, oil-sand, and shale. By 2030, unconventional oil resources, such as heavy oil and oil sands, are expected to play a substantial role in meeting world demand for crude oil (Fig. 3) [9], however, the cost of extracting these resources is expected to be substantially higher, as shown in Fig. 4 [10]. The aforementioned estimations of lifetimes are approximations, since three major factors influence them:


The increase or decrease in production rates as a result of growth in demand for oil and gas, as indicated in Section 1.1.1.


The increase in the size of reserves due to new discoveries, as well as improved recovery methods.


The increase in the size of reserves, depending on rising energy costs, which may make the exploitation of more difficult oil and gas resources, such as ultra-deep hydrocarbon reservoir and deep shale resources, economically viable. The focus of the above review of energy resources was on oil and gas due to their relevancy to this paper. Other energy resources, such as coal, nuclear, hydro, and renewable energy are covered by numerous papers in the literature. However, it is worth mentioning that although the oil, gas, coal, and nuclear resources are still substantial, and will be available to meet world energy demand for many decades, they should still be exploited carefully in selected applications to ensure meeting the long term world energy needs and smooth energy transition towards more sustainable energy sources.

1.1.3. Environmental impact of the oil and gas industry Over the past 4 decades, concerns over the impact of fossil fuels on environment have been growing. Initially, the focus was on SOx and NOx and their direct impact as environmental pollutants. The energy industry was able to cope with that problem, and elaborate and efficient technologies were developed to produce ultraclean petroleum products that are practically free of sulfur and nitrogen. In addition, technologies were developed to scrub stack gases, and reduce the emissions of particulate and sour gases. More recently, the focus of concern has been on the impact of CO2 gases emitted from the use of fossil fuels on global warming. Based on the available data and the continued dependence on fossil energy as

M. Absi Halabi et al. / Renewable and Sustainable Energy Reviews 43 (2015) 296–314

299

Fig. 4. Reserves and cost of exploitation of various oil reserves [10] (EOR ¼enhanced oil recovery; GTL ¼ gas to liquid; CTL ¼ coal to liquid).

300

Electricity Gas Oil

250

Consumption - Mtoe

the primary energy source in the world, the IEA concludes that the amount of CO2 emitted will increase by nearly 40% over the next two decades. The CO2 emissions would increase from the 31.2 Gt of 2011 to nearly 44.1 Gt by 2035. This increase in CO2 emissions, accompanied by the increase in other GHGs, will raise the level of GHGs in the atmosphere to above 1000 ppm of CO2-equivalent. The projected increase in GHGs to a level of 1000 ppm is considered not acceptable. It is expected to raise the average global temperature by nearly 6 1C [2]. In order to restrict global warming to a temperature rise of 2 degrees, one would have to reduce today’s emissions drastically. These concerns left their mark on the energy scene by introducing a number of environmental measures, on both local and global levels, that have impacted the fossil-fuels market in general, and the oil industry in particular. Conventions, such as the Kyoto Protocol (and the more recent Copenhagen Convention on Climate Change), impose restrictions on the levels of CO2 emissions. The oil, gas, and coal industry is attempting to cope with the problem by developing technologies for CO2 capture and storage. However, these technologies are still costly and require further development. One option to offset the cost is the utilization of CO2 for enhanced oil recovery. The industry is also meeting the challenge by introducing bio-fuels. However, the claimed lower ecological footprint of some of these bio-fuels is being debated [11]. This brief review of the status of the world’s energy supply, demand, and the impact of conventional primary energy sources on the environment demonstrates the complicated issues the world is facing in general, and energy suppliers, in particular, with regard to the future of energy. Many parts of the world are approaching the peak in oil production, and their economic growth is highly correlated with energy consumption. Hence, energy sustainability has been global concern and under continuous study. Consequently, the world in the last few decades has been going through energy transition during which new energy systems are being developed and utilities, industries, and transportation are being transformed through efficient energy supply and demand management and exploitation of renewable energy resources. To better manage available resources, every potential for improving and optimizing the utilization of energy supplies should be assessed [12–14].

200

150

100

50

0

Oil Production

Refining

LNG

Pipelines

Fig. 5. Patterns of energy consumption in the oil and gas industry [15,16].

the total oil and gas produced worldwide [15,18]. Hence, assuming that total amounts of oil and gas produced in 2013 and projected for 2035 are 7137 Mtoe [17] and 9960 Mtoe [1], respectively, then the amounts of energy consumed and projected to be consumed by the industry in 2013 and 2035 are estimated to be at least 28.2 EJ and 39.4 EJ, respectively. Most of the energy (nearly 90%) is derived directly from the produced oil and gas. Electricity, which amounts to 10% of the consumed energy, is supplied normally from the electric power grid and does not include the electricity generated on site at some locations. The pattern of energy consumption by various segments of the oil industry in 2004 is shown in Fig. 5. The data in the figure are limited to those compiled and published by IEA, since the data for some countries is not available. The highest percentage of consumed energy goes to petroleum refining, at around 50% of the total, followed by upstream industry at around 30%, oil and gas transportation at around 14%, and finally gas processing at 5% [15,16]. The distribution of the energy consumption by fuel type is natural gas at nearly 48%, oil at 42%, and electricity from the grid at the remaining 10%. The main form of energy usage is thermal energy (over 90%) consumed as:


Direct fuel use for high temperature processes such as hydrogen production, gasification, and direct heating of feedstock.

2. Energy consumption in the oil and gas industry The total amount of energy consumed by the industry based on estimations using 2004 data is around 25.1 EJ (600 Mtoe) [15,16]. The total amounts of oil and gas produced and processed for that same year is estimated at 6349 Mtoe [17], which is around 10% of


Steam generation.

The remaining form of energy is electricity which is used mainly for machine drive, such as compressors, pumps, control systems, etc. The following is an overview of the patterns of energy consumption by the oil industry, which is of relevance to

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Table 1 Upstream costs, exploration and production, in 2009 US$ per barrel of oil equivalent for the period 2007–2009 [19]. Region

US $/barrel

United States Onshore Offshore Canada Europe Former Soviet Union Africa Middle East Other Eastern Hemisphere Other Western Hemisphere Average Worldwide

31.38 51.60 24.76 53.37 20.96 45.32 16.88 16.56 26.64 29.31

the conclusions of this paper. For the gas industry, we are assuming nearly similar patterns are followed. 2.1. Energy consumption by the upstream oil and gas industry Oil and gas exploration, mining and processing varies considerably in terms of complexity. The primary factors that play a role include the location of the oil field, depth of reservoir, the pressure and temperature of the reservoir, the properties of the crude oil, gas, and water produced, the stage of production (primary, secondary, or tertiary), the technologies deployed in production and processing, and the need for gas flaring. This variation is reflected in the wide range of oil and gas production costs reported in the literature (Table 1) [19]. Publications related to energy consumption of the oil and gas up-stream industry are scarce. Glanfield [20] estimated that the average amount of energy required for extracting oil from an oil field at  2.4 GJ/T, and for sand oil at  1.65 GJ/T, without providing details or a breakdown of the energy consumption of different activities related to oil production. Irrespective of the precise amount of energy consumed, it should be pointed out that the main uses of energy in an oil field can be divided into two main activities: exploration and production. For exploration, the energy is mostly used to operate oil rigs for drilling. For production, the energy is used in the form of heat to treat the produced oil, and in the form of electricity to power pumps, control system, cathodic protection, etc. Light crude oil with API gravity greater than 251 in a newly developed field normally requires very little energy to produce and treat. The natural pressure of the reservoir will force the oil out of the well, without external lifting. On the other hand, heavy oils with API gravity ranging between 10 and 201 will have high viscosity and often require pumping, and sometimes heating by injecting high pressure steam in the oil reservoir to reduce the viscosity and drive the oil out of the formation. The heavy oils require also heating, sometimes up to 150 1C or higher, in the surface processing facilities to separate the associated gas and the formation water, as well as to desalt the oil. In addition, to maintain production level from an oil reservoir, the industry resort to injecting part of the produced gas, then water to maintain the pressure, and at later stages it resorts to injection of external gases, such as CO2 or N2, or injection of water with surfactants and polymers. These later steps require substantial amounts of energy. The most important energy resources currently used by the upstream oil and gas industry to meet its energy needs are natural gas, diesel and electricity from the grid (if available). Natural gas is available in the field as associated gas and is used for heating, while diesel is transported to the field and is used to generate electricity if the oil field is located in isolated areas far from the

electricity grid. For heavy oil production and upgrading, heavy fuel oil or coke produced by the heavy oil upgrader is normally used to support steam production, as well as provide the energy requirements of the upgrader.

2.2. Energy consumption by the downstream oil and gas industry Petroleum refineries vary widely in terms of size and complexity depending on both the quality of the crude oil used as feedstock and the volume and specifications of the petroleum products required by the market [21]. The complexity of a refinery is reflected by the number and type of processing units needed to convert the crude oil into products. Petroleum refineries are typically constructed close to the market, i.e., urban centers, where the petroleum products are consumed, and their capacities are normally in the range of 50,000–1000,000 barrel of crude oil per day. As a result of the variation in crude oil quality and refinery complexity, the energy consumption per barrel of petroleum product refined spans wide values. The range of energy requirements of some of the mostly widely used technologies in petroleum refining are shown in Table 2, based on US refinery data [22]. Obviously, the total energy requirements of a refinery vary also widely based on its capacity, quality of feed, and product range. Worldwide data on the total energy consumption by the refining industry are not available; however, scattered reports on few countries or regions have been published. For example, for the United States, the total consumption of energy by the refining industry for 2005 has been reported as 3.345 EJ (79.7 Mtoe; 3186.2 trillion Btu) to meet both the heat and electricity requirements. The energy was used to refine around 780 MT of crude oil as input to distillation units, which leads to  43 TJ/T, and that the US refining industry energy efficiency is around 10.2% based on its hydrocarbon input. For an average refinery with a capacity of 200,000 bb/day, the energy consumption is estimated at around 42,700 TJ. The ranges of energy consumption and the energy efficiencies of the main energy technologies per barrel are shown in Table 2, and the approximate percentage contribution of these processing technologies to the total energy required to refine oil is shown in Fig. 6. The consumption of energy in the form of heat or steam is the dominant one for most technologies ranging from 80 to 99%. The main primary energy resources used by the industry are natural gas (22%), refinery gas (45%), catalyst coke (17%), and purchased electricity (12%) [22]. For extra-heavy crude oil, the industry normally sets up upgraders near the oil fields, which typically consist of a distillation unit and a residual oil processing unit, such as a delayed coker. The upgrader is used to process the crude oil with the aim of producing synthetic crude oil with improved quality to meet the requirements of petroleum refineries. The energy requirements of Table 2 Range of energy consumption of selected petroleum refinery processing units [22]. Refinery technology

MJ/barrel

Atmospheric crude distillation Vacuum distillation Fluid catalytic cracking Catalytic hydrocracking Delayed coking Catalytic reforming Alkylation Catalytic hydrotreating Hydrogen production

86–196 53–119 220 168–339 120–242 224–360 269–359 64–173 66–167

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such upgrader are substantial, and are currently met using either fuel oil or coke produced by the upgrader. 2.3. Factors impacting future energy consumption of oil and gas industry Energy consumption by the oil and gas industry is expected to increase due to the following factors:


The need for adopting secondary and enhanced recovery









techniques in conventional oil fields to improve recovery, including increasing need for water to support oil production operations. The rising dependence on heavy crude oil resources, for which energy in the form of steam is required if they are to be extracted. The continuous drop in crude oil quality, both in terms of the American Petroleum Institute’s API gravity and sulfur content, which dictates the use of energy-intensive conversion and hydrotreating processing units to meet market demands for petroleum products. Increasing need for energy-intensive conversion and hydrotreating processing to upgrade heavy oil and for production of cleaner fuels. More stringent environmental regulations, including reduction of CO2 emissions, which require the introduction of energydemanding treatment units within both the upstream and the downstream industries.

The industry can reduce the impact of these factors on energy consumption through appropriate energy management programs. It can also reduce the environmental impact of its energy usage through the introduction of renewable energy resources into its energy mix. The subject of energy management and energy conservation is beyond the scope of this review.

3. Potentials of renewable energy in meeting the energy requirements of the oil industry The oil industry offers a wide range of potential for the application of renewable energy to meet its energy requirements. These include replacement of conventional electrical energy sources, either grid supplied or off-grid generators, with photovoltaic (PV) systems or wind mills to power a variety of equipment and instruments throughout the production chain (e.g., well pumps, gathering centers, and pipelines). The applications also include replacement of conventional steam generation and heating requirements with solar thermal or geothermal systems, and in more distant future, the use of solar energy directly in energy intensive processes. These potentials are particularly important taking into consideration the geographical location of conventional oil reserves, mostly in the Middle East and North Africa (MENA) region, and the future trends of the oil industry, which were highlighted in Section 1.1.2. Furthermore, Fig. 7 shows the locations of the most important heavy oil reserves in the world superimposed over world solar irradiance map [23,24]. As can be seen, most reserves are located in regions with high solar radiation, which implies that exploiting solar resources in these regions is expected to be cost effective. This will be particularly true for solar thermal technologies, which require high direct solar irradiance to improve their economy. In the following sections, an overview of the current status and the potential applications of renewable energy within the oil and gas industry are provided.

Hydrogen Production

Alkylation

Catalytic Reforming

Catalytic Hydrotreating

3.1. Providing electrical power to oil and gas production operations Delayed Coking

5%

Catalytic Hydrocracking

10%

Fluid Catalytic Cracking

15%

Vacuum Distillation

20% Atmospheric Crude Distillation

Contribution to Total Energy Consumption (%)

25%

301

0%

Fig. 6. Average percentage contribution of main petroleum refining technologies to the total energy consumption for processing crude oil by refineries (data from [22].

One of the earliest applications of solar energy within the oil industry involved the use of PV panels to generate electricity for special field applications. Foremost among these applications are the off-grid warning lights for offshore installations. Exxon was among the first companies to use this technology in such applications in the early 1970s [25]. Since the use of PV panels resulted in substantial savings, both in terms of capital investment (i.e., cost of batteries) and operating costs (i.e., maintenance of the system),

651 971 182

1127 168

Fig. 7. Global solar irradiance map [23] and distribution of heavy oil and natural bitumen reserves (blue bars in billion barrels) [24]. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

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the technology was rapidly adopted by all of the major oil companies: Amoco, ARCO, Chevron, Exxon, Texaco, and Shell. Other oil field applications include cathodic protection of pipelines and well casings from corrosion. This is particularly useful in areas where utility electricity is not accessible. One of the earliest studies addressing this issue was initiated in 1974 [26]. An assessment was first conducted on various options to replace the Mg anode beds, which were not adequately protecting the well casings in the 516 old Hugoton Field wells and the 125 new Panoma Council Grove Field gas wells. The options considered included rectified conventional power, thermoelectric generators, wind chargers and solar panels with lead-acid storage batteries. All of these options, with the exception of the solar panels, were either not practical or not economical. Following a preliminary assessment, a pilot study was conducted involving 30 stations for a period of 6 months. It demonstrated that the use of PV panels was both economical and practical. At present, most major oil companies and other companies supporting oil-field operations use or have plans to use PV-based power generation technology for cathodic protection as well as to meet the power requirements of oil rigs and other oil-related installations in remote locations for both on-shore and off-shore applications [27–30]. Documentation concerning the performance of PV applications in the oil sector is scarce. Teale [31] reported the results of three years of field experience with PV solar panels powering a 1000-km microwave chain of radio repeaters along main oil pipelines of Petroleum Development Oman (PDO). Solar generators and load currents were integrated by means of on-site instrumentation; the results were recorded monthly. Computer analysis allowed detailed performance monitoring as well as development of a data bank for the economic design of new stations. Among the main factors that impacted the performance of the system were the following:


Dust, which had to be removed monthly.
Bird droppings, which had to be washed off with water.
High temperatures for the panels during the summer, which significantly reduced the voltage of such panels.


Variation of the load, which was resolved by having a margin of at least 15% excess charge over and above the normal load. Chevron Energy Solutions carried out one of the more recent and larger-scale applications for utilizing solar PV panels in oil field operations. PV panels were used to provide power to oil pumping units and processing plants. The project, at the time, involved the largest array of flexible, amorphous-silicon solar technology in the world, with a capacity of 490 kW (AC) from a 614-kW (DC) array. The plant, which was called Solarmine, extended over nearly 24,000 m2 and was connected to the local electric distribution grid. The facility consisted of 4800 panels mounted on metal frames. The panels were supplied by the United Solar Systems Corporation (Uni-Solar), a subsidiary of the Michigan-based Energy Conversion Devices, Inc. (ECD), which is partially owned by ChevronTexaco. The project was aimed at assessing the impact of environmental factors, such as heat and dust, on the performance of the panels. The performance of the Solarmine plant was reported after two years of operation by Gregg et al. [32]. The plant was found to perform consistently in accordance with the design goals, and sometimes exceeded them by 5 to 10%. The system generates a total of 1000,000 kW h annually. 3.2. Meeting oil production industry thermal energy needs Solar thermal energy can be exploited through numerous categories of technologies [33]. Some of these technologies are

well established and are commercially proven and cost effective for either power generation or steam and/or heat generation to meet selected industrial or home use needs. Others are still either at the demonstration, pilot-plant or applied research stage. Research efforts to improve the efficiency and cost effectiveness of solar thermal systems are in progress in various research laboratories worldwide. IEA has an elaborate platform for the development of solar thermal technologies. The current emphasis is on concentrated solar thermal (CST) technologies [34,35]. To support the development of solar thermal technologies, IEA developed in 1977 the IEA Implementing Agreement Solar Power and Chemical Energy Systems (SolarPACES13). SolarPACES [36] has currently 19 member countries, including three countries from the oil and gas rich MENA region, Egypt, Algeria, and the United Arab Emirates. SolarPACES is currently focusing its work on optimizing the cost of solar thermal technologies, standardization, solar heat for industrial processes, solar chemistry, and solar water treatment processes. In addition to SolarPACES, IEA has also another program, the Solar Heating and Cooling Program, IEA SHC [37], which also addresses issues related to solar thermal technology. The program has been in progress since 1977. Some of the main relevant and current activities of this program are the development of polymeric materials for solar thermal applications, solar rating and certification, and solar process heat for production and advanced applications. The European Renewable Energy Research Centers Agency (EUREC) has also published its forecast of research and development (R&D) needs up to 2020 and beyond [38]. For CST and low and medium temperature solar thermal technologies, the report identified the following research themes:


Demonstration of concentrated solar power plants with high



temperature storage and high-pressure turbine steam for electricity generation. Demonstration of solar fuel upgrading at commercial scale, e.g., steam reforming of natural gas. Improvement of low/medium temperature technology through development of improved materials for components and transfer fluids, integration of solar heat in existing industrial processes, new testing procedures including accelerated ageing tests of solar system, demonstration units in different processes to convince industrial companies about the benefits of solar technology, development of solar thermo-chemical cycles and solar thermal high temperature electrolysis for hydrogen production, and solar processes for incorporating carbonaceous resources with emphasis on solar steam reforming of methane and solar methane cracking.

These research efforts are expected to lead to significant improvements of solar thermal systems, thereby making them more cost effective and opening more opportunities for industrial applications.

3.2.1. Low–medium temperature solar thermal applications: Process heat The technologies that belong to this group are based on solar thermal technologies that have been in commercial applications for several decades mostly for home applications. Many of these technologies are based on simple black absorbers capturing direct solar irradiation using metallic absorber sheets coated with a special high-performance black coating. The two main types of panels are the flat plate and the evacuated tube. Operating temperatures of up to 80 1C are normally achieved with good efficiencies. Other designs for medium temperature collectors

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Fig. 8. A schematic diagram of integrating low–medium temperature solar system with the desalting unit of a gathering center (K. Vajen, personal communication).

Table 3 Summary of concentrated solar thermal technologies. Technology

Operating temperature (1C)

Optical efficiency [39a] (%)

Remarks

Parabolic trough Fresnel reflector Central receiver Parabolic dish

500 500 1000 1000

14–20 18 23–35 30

Mid-to-high process heat Mid-to-high process heat High temperature process heat Stand-alone small systems or clustered to larger dish parks

developed recently are equipped with concentrating mirrors to increase operating temperatures to a range of 200 to 400 1C. The main applications of the simple non-concentrating technologies are currently for home heating and/or cooling purposes. Concentrating technologies are used for driving absorption chillers, for instance. Moreover, efforts are being made to develop applications to meet industrial medium temperature requirements and direct steam production. Solar heating of up to 80 to 200 1C as a heat source for industry heating have been considered for wide application in industries (food, petrochemical, etc.) in the European Union (EU) countries and also in China. The solar collectors will have a market capacity more than ten times of the current solar thermal market. These mature technologies and products will be very beneficial for solar cooling applications, where highly efficient solar cooling could be realized. One potential application of solar energy in oil field operations is the supply of low–medium temperature process heat required for operations such as degassing, dewatering and desalting. An effort to assess this application is being pursued by Kuwait Petroleum Corporation in cooperation with the authors of this review. The temperature required for such applications falls in the range of 80 to 150 1C. A schematic of a pilot plant under consideration to assess this application is shown in Fig. 8 (K. Vajen, personal communication). Other potential applications include using these low–medium temperature technologies in hybrid heating systems to supplement the use of fossil fuels.

3.2.2. High temperature solar heating applications in oil production: Enhanced oil recovery Concentrated solar thermal (CST) technologies are well established and are commercially proven for either electrical power generation or heat generation to meet selected industrial needs. A list of these technologies, their operating temperatures, and optical efficiencies are shown in Table 3 [39a]. Several commercial

products are already available in the market. The cumulative capacities of plants adopting these technologies that are either operating, under construction, or in advanced planning state are nearly 14.5 GW [39b]. The parabolic trough is the most widely used technology, followed by solar tower. Most current applications are related to power generation. However, there has been some recent interest in using these technologies to produce high temperature steam for some applications. The main problem of using these technologies in regions such as MENA is the loss of efficiency due to dust deposition. Other CST technologies that are currently in the semi-commercial demonstration and pilot stages include linear Fresnel reflectors and solar towers. These technologies are expected to reach a mature commercial stage over the coming 5 y. One advantage of the Fresnel technologies is that they have no moving parts in the receiver part; hence, they could prove to have better energy and cost performance in dusty environment. Based on the IEA roadmap on solar thermal technology [34,35], concentrated solar power offers a number of advantages and opportunities such as the following:


It is well suited for the oil-rich MENA countries.
Dry cooling is possible, especially in water-poor countries such as those in the Middle East.


Concentrated solar power usage can be extended easily to other applications for the process industry. One of the main potential applications for CST technology in the upstream industry is the generation of steam required for heating and enhanced oil recovery (EOR). Solar thermal technology can produce high-pressure steam with temperatures reaching as high as 550 1C. The main drivers for solar energy usage in EOR are [40,41] the following:


Steam temperature requirements for EOR are in the range 115 to 300 1C.

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Natural gas is currently the predominant fuel used to generate






steam, but it is rapidly becoming expensive due to short-falling supply. Alternative fuels such as coal, heavy oil, or by products of heavy oil upgrading could be used, but they would release large quantities of CO2 (an additional 10 to 30% of lifecycle emissions of the resulting oil) unless capture and sequestration methods are employed to minimize GHG emissions. Nuclear power has also been proposed, but remains controversial. The use of concentrated solar energy can play an important role. It would provide huge monetary savings, a hedge investment against potential carbon tax regulations, and an environmentally friendly way to exploit heavy crude oil reserves.

Investigations into the potential of this type of application date back to the 1970s. One of the earliest studies of this type was conducted by Exxon in its Edison oil field in California. From 1979 to 1980, Exxon, Foster Wheeler and Honeywell conducted a feasibility study commissioned by the United States (US) Department of Energy (DOE) [42,43] to assess trough solar collector systems and the solar thermal enhanced oil recovery (STEOR) market. The study concluded that the economics of STEOR will be unfavorable due to the high cost of hardware, and recommended that the DOE provide assistance to induce the owners of any pioneering STEOR projects to try again the solar systems on a larger scale. Despite this early negative recommendation, Foster Wheeler continued the work on engineering and constructing solar thermal systems to supply hot water and process steam to the process industry [44]. In 1982, ARCO Solar, with the cooperation of the ARCO Oil and Gas Company, completed the installation and began the operation of a highly automated central-receiver solar thermal pilot plant with a capacity of 1 MW of thermal power in the form of 80% steam. The study concluded that centralreceiver solar systems can be very effective sources of power for generating steam for the enhanced recovery of heavy oil [45]. It appears that, as the price of oil dropped down in the mid-1980s, interest in the development of solar energy technology also dropped. More recently, the use of solar energy for EOR began to gain momentum again, largely due to the high price of oil. This is in addition to the recent developments in solar thermal technology, which led to the introduction of concentrated solar thermal technologies, such as Fresnel linear concentrator technology and advanced solar tower technologies, which can capture solar energy either more cheaply or with increased efficiency. The main argument is not one of efficiency, but of the cost of energy generation, which is mainly dependent on solar irradiations levels and investment cost. Table 3 shows a list of various high temperature solar thermal technologies, and the steam temperatures that can be reached. Indicative of the rising interest in solar thermal applications was Chevron’s signing of an agreement with BrightSource Energy, a company specializing in solar thermal power and building a demonstration plant in Coalinga, California. The plant generates steam to extract oil from a field owned by Chevron [46]. The steam production capacity of the plant is 29 MWth. The steam is generated by reflecting sunlight through approximately 7000 flat mirrors to a boiler located at the top of a 98-m tower. The project helped Chevron reduce its dependence on natural gas for direct injection or steam generation, and reduced the company’s carbon footprint while gaining a hedge against volatile natural gas prices. The plant began operation in 2010, and 60% quality steam is generated at 260 1C (500 1F) and 48 bar (700 psi) [46]. BrightSource as well as other main competitors like Abengoa, Ausra, Solar Power Group and eSolar are also looking towards other oil companies as a very promising potential market for their

Fig. 9. Schematics of a proposed solar-enhanced oil recovery system for oil sands (adapted from [55]).

solar thermal systems [47]. eSolar uses a tower technology, while Ausra, Solar Power Group and Novatec Biosol promote different versions of a linear Fresnel reflector (LFR) solar collector to produce steam. Nearly flat modular reflectors focus the sun’s heat onto elevated receivers. Ausra, for example, began the construction of a 5 MW demonstration solar power plant outside Bakersfield, California. The company held discussions with oil producers about deploying its technology for EOR. Novatec Biosol runs a 1.3 MW solar plant outside of Murcia, Spain. Within the Gulf Cooperation Council (GCC) region, Petroleum Development Oman (PDO) has taken a step forward in exploiting solar energy for its enhanced oil activities. A simulation study by Shell for PDO has shown that the oil recovery from solar-generated steam injection and that from constant-rate steam injection, using conventional steam generation fueled by gas, are essentially the same, for fractured reservoirs and non-fractured reservoirs [48]. Hence, it was concluded that solar-generated steam provides a viable option for steam EOR. A concentrated solar thermal pilot plant was constructed and commissioned in 2012 at Amal West oil field. The solar energy system was integrated with a conventional steam-generating plant already in place. The mirrors and receivers are contained within a glass structure, with a total area of 17,280 m2 which acts as protection against the harsh outdoor elements. The plant’s capacity is estimated to average at around 50 t of steam per day, with a peak output of 11 T/d (around 7 MWth) [49–54]. Reported results for the steam conditions are 100 bar and 312 1C. The plant will save nearly 49,500 GJ (47,000 MMBtu) of gas annually. A report on the performance of the plant was recently presented by Bierman [54]. The plant was able to achieve over 97% of its theoretical output, generating over 80 t of steam per day. A dust storm caused the plant performance to degrade by around 12%, but this was remedied after cleaning the dust. For oil-sands and unconventional oil, Kraemer et al. [55] proposed and provided a thermodynamic and financial assessment for an oil recovery scheme. The scheme is based on generating steam using solar thermal panels to meet the needs for steam-enhanced oil recovery, as well as to generate the power necessary to run pumping equipment using solar thermoelectric generators (Fig. 9). The advantage of the proposed method lies in the cogeneration of electricity and heat. It was concluded that solar-powered steam generation for bitumen recovery from oil sand would be cost effective and would have higher reliability than gas-based EOR, taking into consideration the volatility of gas prices and supply disruption, and potential carbon tax regulations. These conclusions and the viability of solar thermal EOR were more recently confirmed by Sandler et al. [56], based on reservoir

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simulation, economic analysis, and life cycle assessment. The data are based on Kern River oil field, San Joaquin Valley, CA. The daily cyclic fluctuations of solar steam did not have significant impact on recovery. It was also found that the proposed solar thermal plant has a very good ratio of energy output to input, which is not the case for many alternative energy sources, such as the bio-fuel corn ethanol. The study concluded that while solar thermal steam generation is feasible for thermal EOR in areas with high solar insolation, it is preferable to have it in combination with conventional steam generation schemes. The impact of the fluctuation of solar steam generation due to variation in solar radiation on EOR of heavy oil sands was investigated by Agarwal and Kovscek [57]. A coupled geomechanical and reservoir modeling analysis was conducted, and no negative effects were observed. The cyclic nature of solar steam injection does not cause reservoir deformation or affect flow performance. It was concluded that solar generated steam injection appears to be viable for thermal EOR in permeable sand formations. However, it should be noted that this study is focused on high porosity formation; low permeability formation may behave differently. Another solar thermal application is the Helitherm system, which is a passive, stand-alone, solar-thermal-powered heating system for pipelines and vessels. Developed by the Australian company Solar Systems Pty [58], the system operation relies upon an integrated thermal diode, which traps sunlight and retains heat. The system was designed for use in crude oil and product flow enhancement and heat tracing in above-ground installations. It is offered as an economically attractive alternative to conventional heat tracing of pipelines or the use of drag-reducing agents or pour-point depressants.

3.3. Solar applications in oil-field water desalination and treatment Another important promising application of solar energy in the upstream industry is the desalination of brine water produced from oil and gas wells. The ratio of water to oil in some fields may reach as much as 10:1. Oil-field formation water is typically contaminated with traces of oil, metals, gases, and high levels of mineral salts. The disposal of this water normally poses a serious environmental problem. In addition, most oil and gas fields are in dry, semi-arid regions, which have extremely limited water resources. Based on the aforementioned, desalinating or treating waste formation water to produce freshwater suitable for agriculture or to meet oil production needs is highly desirable. The role of solar energy is to provide the energy required for desalination at a reasonable cost. Various solar-powered desalination technologies have been reported as options for such energy generation. Some of the applications developed are small, solar-powered, decentralized desalination units (driven by either thermal or electric energy). However, large solar thermal power plants are also developed in combination with large multi-effect distillation plants (MED) or possibly multistage flash (MSF) plants also. Verbreek et al. [59] reported the results of a joint effort between Royal Shell and Solar Dew BV to develop Solar Dews, a novel technology for purifying water. The technology is based on a special, nonporous membrane combined with solar energy. The contaminated water is heated up at the top part of the panel by the sun, causing the water to evaporate. The water vapor passes through the membrane and condenses on the bottom side of the panel, while the concentrated contaminated water passes through the top side of the panel [60]. The technology was tested extensively in southern Oman in 2001, in laboratory and field. There were plans to run scale-up trials in 2002, to assess the

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performance and cost on a large scale; however, no results are reported. Nafey et al. [61] experimented with a small test unit to assess the performance of water desalination by solar energy and a flash evaporation process. The system consists of a solar water heater (i.e., a flat-plate solar collector) working as a brine heater and a vertical flash unit that is attached to a condenser and pre-heater unit. The study showed that the average accumulative productivity of the system in November, December and January of 2006 ranged between 1.04 and 1.45 kg/d/m2. The average summer productivity ranged between 4.2 and 5 kg/d/m2 in June and 5.44 and 7 kg/d/m2 in July and August 2006. Producing freshwater with this solar desalination system, given its simplicity, would be one of the best solutions to supply water for small groups with no technical facilities. Barrufet and Mareth [62] reported that the petroleumcontaminated water should first be treated to remove undesirable hydrocarbon contaminants, and then the brine should be desalinated using reverse osmosis (RO). The electrical power needed to operate an RO unit could be supplied by a power generating system based on solar energy, wind, or diesel, or a hybrid of these three. The freshwater that is produced is normally of high quality, and is sufficiently pure for agricultural, industrial, or potable usage. The cost effectiveness of such treatment depends on the quality of the brine and the efficiency of the renewable energy system. Liu et al. [63] designed a small solar multi-stage desalination system consisting of 4 linked units. The solar collecting and desalinating unit is a compound parabolic concentrator and an all glass evacuated tube collector. The unit can generate as much as 1.25 kg fresh water/m2, with an efficiency of 0.9. Asadi et al. [64] also reported the design of a desalination system based on pervaporation to purify high saline wastewater from a gas refinery. The produced water meets the quality required for agricultural use. 3.4. Applications of other renewable energy resources in oil production industry In addition to solar energy resources, other renewable energy resources are already contributing to meeting the energy demand of the oil production industry. For example, Shell reported the design of a Monotower Platform incorporating renewable energy generation equipment, which reduced the cost and environmental impact of installing a sub-sea cable to provide power to the platform. The technologies deployed in these platforms include both wind turbines as well as PV panels. Two platforms of this type were installed in 2005, and others are planned [65,66]. More recently, Cornelia and Davies [67] examined the potential of replacing fossil fuel by renewable power, including solar, wind and ocean sources, to meet off-shore power demand. The study focused particularly on the potential of ocean energy, for which the power capacity was estimated to be 7380 GW, distributed mainly between wave, ocean thermal energy conversion (OTEC), and salinity gradient. The assessment concluded that while solar and wind technology are already proven and commercialized, OTEC has good potential for some off-shore locations, where the thermal gradient between surface and sea bed is greater than 20 1C. Geothermal energy is another resource that has the potential possible for exploitation in the form of heat, electricity or a combination of both to meet future energy requirements. Taking into consideration the temperature of oil formation, which may go up to 130 to 150 1C, it is theoretically possible to utilize the heat gradient between the formation and surface temperatures to generate heat, and possibly power. The heat may simply be generated as a by-product of water injection operations for improved oil recovery.

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Fig. 12. Solar up-field upgrading of heavy crude oils.

Fig. 10. Selected high temperature oil and gas processes.

solar energy to support refineries needs. Along this line, a number of promising solar thermal energy technologies are currently under development. They are mainly focused on the direct use of solar energy to provide high temperature heat to meet the needs of highly endothermic chemical reactions. The main reactions that are targeted include the following:









Fig. 11. Potential application in petroleum refining: off-site reforming and cracking.

Some pilot plants based on this concept are already in operation [68]. A recent paper by Gong et al. [69] addressed some of the concerns by assessing the impact of injecting water at 35 1C on the decline of the formation temperature, which is originally at 120 1C. It was concluded that the water re-injection rate and temperature must be closely examined to avoid significant drop in formation temperature. Falcone and Theodoriu [70] and Zahoor Ullah and Bukhari [71] suggest that the oil and gas industry, with the wealth of know-how and technologies it has, can transfer this knowledge to the exploitation of geothermal resources, thereby accelerating the development of available resources.

4. Potential applications of renewable energy in downstream industry applications In comparison with the upstream industry, the processes of the downstream petroleum industry are characterized by being high-density, energy-intensive processes that takes place at high temperatures. Foremost among the processes that consume high levels of energy are distillation, hydrogen production, and high-pressure steam generation. Hence, solar thermal technologies are the most promising candidates. The review of the literature revealed that no industrial-scale applications of renewable energy have yet been attempted in the refining industry. A number of constraints limit the potential of directly using renewable energy resources in support of refining operations. For example, solar thermal technologies such as parabolic trough or central receiver, which can deliver high temperature steam, require wide areas of land. However, refineries are normally constructed near urban areas, where open land is very limited. Another major constraint is the intermittent nature of solar energy, which dictates that either a hybrid system or energy storage must be deployed. Nevertheless, there is a potential for indirectly utilizing

Steam reforming reaction: CH4 þH2O-3H2 þCO. Heavy oil cracking reactions: CnHm-CaHb þCdHe þ etc. Gasification: CnHm þ H2O-xH2 þyCO. CO2/methane reforming: CH4 þCO2-2H2 þ2CO. Methane coupling: CH4-C2H4 þH2. Thermochemical water splitting: 2H2O-2H2 þO2.

These reactions, which are important to the petroleum refining and petrochemical industries, require temperatures in excess of 400 1C, as shown in Fig. 10. The subject has been recently reviewed by Trainham et al. [72]. Breakthroughs in these lines of research will have very significant impact on the energy scene worldwide. For example, the successful development of an economically viable process for solar steam reforming, solar cracking or hydrogen production by direct water splitting will enable the petroleum industry to upgrade the huge heavy oil and shale resources and convert them into fuels with minimal environmental footprint, as well as provide the petroleum refining industry with hydrogen to produce clean fuels. It is important to note that any of the afore mentioned reactions could potentially be carried out in plants constructed up-field in isolated areas away from refineries, where open land is available, and the products can easily be transported through pipelines. Fig. 11 shows one potential scheme for producing hydrogen or synthesis gas near an oil field using solar reforming. Simultaneously, excess heat from the process can be used to support the thermal energy needs of the oil production operation. In this scheme, heavy residual oil from the refinery can be pumped up-field for solar cracking and the cracked products are transported back to the refinery for further processing. Fig. 12 shows another option for integrating solar energy with a heavy crude oil upgrader. In this scheme, the cracked residual oil from the upgrader is fed to a solar gasification unit to produce hydrogen and/or syngas that can be exported to a refinery or marketed as hydrogen fuel. Simultaneously, the CO2 and steam that are produced as side products are returned to the oil field for usage in EOR through either steam or CO2 injection. Alternatively, it is possible to envision setting up dedicated facilities for solar hydrogen production up-field using thermochemical water splitting to meet the increasing needs of the refineries for hydrogen for the production of clean fuels. Another potential application is the use of solar energy in refinery waste water treatment. In the following sections, some highlights will be provided of the developments of the aforementioned technologies related to gasification, hydrogen production, and solar reactors.

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4.1. Hydrogen and synthesis gas production The Steinfeld Group at Eidgenössiche Technische Hochschule, Zurich University, and the Solar Technology Laboratory of the Paul Scherrer Institute in Switzerland have taken a different approach to hydrogen production by attempting to utilize solar energy to meet the energy requirements of conventional gasification reactions. An initial, thorough, thermodynamic and kinetic analysis of the gasification of petroleum coke to produce hydrogen showed a nearly 50% reduction in CO2 emission [73]. Further experimental work by Z’Graggen et al. [74–77] resulted in the design of a solar reactor for the gasification of various carbonaceous materials, including petroleum coke, waste material, and vacuum residue. The solar reactor is a 5-kW prototype tested in a high-flux solar furnace at temperatures in the range of 1025 to 1525 1C for steam gasification of coke. The reactor yielded up to 87% petroleum coke conversion. The typical composition of the syngas produced was 62% H2, 25% CO, 12% CO2, and 1% CH4. The solar energy conversion efficiency, defined as the portion of solar energy absorbed as chemical energy and sensible heat, was 17%. Stein et al. [78] recently the reviewed solar thermal reforming using concentrated solar energy instead of combustion of fossil fuels. They pointed out that the process is a good method for solar energy storage as it reduces carbon intensity, thereby overcoming some of the shortcomings of solar energy. An alternative space for hydrogen production was also investigated via a two-step water-splitting thermochemical cyclic process [79]. In the first step, Mg is produced by carbothermal or methano-thermal reduction of MgO, using concentrated solar energy as the source of high-temperature process heat. The second step involves the steam hydrolysis of Mg for the production of H2 and MgO. The reduction of MgO was performed in the temperature range of 1450 to 1550 1C using wood charcoal and petroleum coke as reducing agents. Another alternative route for syngas production is the conversion of CO2 and H2O using solid oxide fuel cell materials. The production system uses solar concentrator PV to generate electricity and heat, and high temperature coelectrolysis to electrolyze the CO2 and H2O. The produced gas can be converted into chemicals or fuels through several wellestablished processes [80].

Fig. 13. Schematic of a two-zone solar reactor configuration showing the fast pyrolysis drop-tube zone and the trickle-bed gasification zone [87]. RPC¼ reticulate porous ceramic, CPC ¼ compound parabolic concentrator.

Hoffmann [86], a fiber-optic photocatalytic cable reactor was used to treat organic pollutants using solar radiation. It was observed that it is possible to degrade 4-chlorophenol effectively. In addition, the reactor may prove useful for in-situ, passive decontamination of subsurface and other remote environments. An example of such a solar reactor system used for biomass gasification is shown in Fig. 13 [87]. The reactor consists of two zones. The first zone is a drop-tube to achieve fast pyrolysis of the carbonaceous material. The second zone is a trickle bed reactor with structured packing material that increases solids holdup in the hot zone to achieve the desired gasification and decomposition of the pyrolysis products. The reactor was tested at a 1.5 kWth solar radiative power input. This reactor was noted to gasify C1 and C2 hydrocarbons more efficiently than a drop-tube gasifier, with higher concentrations of H2 and CO2 and lower concentration of CO. Further research is still required to demonstrate the performance of the reactor at higher throughputs and longer operation durations.

5. Role of oil and gas companies in developing renewable energy technologies

4.2. Developments in photocatalytic reactors Photocatalysis offers a good opportunity to couple the use of solar energy with some of the needs of the processing industries, such as offering alternative routes for chemical synthesis, production of fuels, and waste treatment. The main challenge in this field is the development of appropriate photoreactors that are possible to scale up. The subject has been reviewed most recently by Van Gerven et al. [81], Braham and Harris [82], and Puig-Arnavat et al. [83]. It appears that compound parabolic and double-skin sheet reactors are the most suitable for near-term larger-scale applications. Other potential designs that have potential of further development include the inclined-plate photoreactors and the fluidized-bed photoreactors. Numerous laboratory- and bench-scale developmental research initiatives have already been reported in the literature. For example, The-Vinh and Wu [84] reported photocatalytically activated CO2 reduction with H2O in an optical fiber reactor to produce methane or ethylene. The reactor is catalyzed by a combination of metallic catalysts on either TiO2 or TiO2–SiO2 support. For wastewater treatment, Dillert et al. [85] reported the photocatalytic decomposition of organic pollutants in biologically pretreated industrial wastewater samples using a double-skin sheet reactor and artificial solar light. Significant reduction of the concentration of organic compounds was observed. In another study by Peill and

The position of the oil and gas companies with regard to the development and application of renewable energy has fluctuated over the past 4 decades. During the 1970s and 80s, almost all international oil companies initiated programs and businesses to develop renewable energy technologies. Some companies continued their activities, while others abandoned their efforts completely [88]. The strategic outlook for oil and gas was the main driving force during the 1980s. Exxon, Chevron, BP, and Shell initiated active solar energy research programs since the early years of the 1970s. The programs were focused on developing solar cells and solar systems, and resulted in an impressive list of patents. Both Exxon and Chevron almost stopped their research efforts in this field at the early 1990s, on the basis that renewable energy resources will continue to play a marginal role in the world’s energy scenes for many decades to come. BP and Shell continued their developmental efforts, but with a lower pace. The main drive for the post-1990 efforts, which for most companies was focused on applications, appears to be the need to reduce GHG emissions, to diversify energy sources, and ensure long-term security of supply [89–93]. According to Dittrick [94], most international oil companies have established subsidiaries and partnerships to develop alternative and renewable resources in anticipation of the global need to diversify energy supplies. Exxon had two subsidiaries specialized in solar

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thermal technology and PV technology. BP established Solarex, then BP Solar and BP North America. Royal Dutch Shell established Shell Renewables in 1997, focusing on wind and thin-film solar power [95]. The cumulative size of BP Solar’s business was recently announced to have reached the milestone of cumulative sales of one GW-supplying 10 million solar power modules, and saving 4 million t in CO2 emissions [96]. In 1999, Chevron formed Chevron Technology Ventures (CTV), which is a subsidiary assigned the mission of managing innovation, commercialization, and integration in the area of emerging technologies. CTV [97] basically invested in technology startup companies, whose innovations could significantly benefit Chevron’s existing businesses and lead to new growth opportunities, including opportunities in the renewable energy field. Chevron also launched its subsidiary, Chevron Energy Solutions, in 2000 [98], as its arm for energy-related projects. The company focused on applying energy efficiency and renewable energy technologies, and armed with Chevron’s experience in engineering and construction to provide a variety of services, such as energy assessment and clean-energy engineering [99]. The company has a total installed capacity of 22 MW with a total of 128,000 panels. It has developed hundreds of projects involving energy efficiency and renewable power for education, government and business customers in the US since 2000 [98]. Renewed interest in promising, new renewable energy technologies, specifically biofuels from agricultural products and algae, has been noted over the past 10 years. In 2009, ExxonMobil announced a major investment, of nearly US$ 300 million, in one of the leading technologies that are under development for producing bio-fuels [100]. The technology is based on using genetically modified algae developed by Synthetic Genomics, Inc., to assist in the production of oil that can be fed to petroleum refineries to produce a number of products such as gasoline, jet fuel and diesel. Both parties will work to develop the technology for converting algae into oil, and to develop the engineering design for a plant for commercial production. In a trial by Continental Airlines, the algae-derived jet fuel was tested and proved successful. This route for bio-fuel production is favored over other bio-fuels, such as ethanol and oil plants, since it does not impact the food chain and does not utilize the land dedicated for agricultural food production. Chevron has also been concerned with the development of long-term solutions to meet the issue of the rising demand for transportation fuels. The company has been considering a range of innovative alternatives that supplement petroleum products. It has developed industrial partnerships and a number of collaborative research programs with the US DOE’s National Renewable Energy Laboratory (NREL), the Georgia Institute of Technology, Texas A&M University, the University of California at Davis, and the Colorado Center for Biorefining and Biofuels [101]. The objective of these collaborative efforts is to develop biofuels from non-food raw materials. A joint venture was established by Chevron in 2008, with the Weyerhaeuser Co., a company that has extensive experience in forestland development, under the name of Catchlight Energy LLC [102]. The new venture focuses on technologies to convert forestry products into fuels. Finally, it is important to note that Chevron is currently the largest producer of geothermal energy in the world. The company has a total installed capacity of 1273 MW in the Philippines and Indonesia. Shell sold its silicon-based solar panel business in 2006, and arranged with the glass company Saint-Gobain Glass Deutschland to establish the joint venture, Avancis, which is to specialize in solar power panel manufacturing using advanced Copper Indium Diselenide (CIS) technology. The move towards utilizing the advanced CIS thin-film technology was made because of the potential of a real-cost breakthrough for solar power [103]. Total has also been active in renewable energy since the 1980s [104],

particularly wind and photovoltaic, through its subsidiary, Total Energie, and with the support of Photovoltech, which is a company specialized in producing highly efficient multi-crystalline silicon cells. Total is also participating in developing thin-film solar with Atotech in Germany. The company is maintaining its commitment to renewable energy with a strategic view that a breakeven point would be reached that would shift solar energy from a subsidized economy to market economy. The oil companies in the MENA region, which as indicated previously enjoy high level of solar radiation, are also initiating efforts to assess the potentials of introducing solar energy to meet some of their energy requirements. Also, Abu Dhabi developed a 100-MW solar thermal power plant, SHAMS 1, within its Masdar Initiative, which began operation in 2013, and is predicted to reduce CO2 emissions by around 175,000 t annually. Partners in this project is Total, the French multinational integrated oil and gas company [105]. In Kuwait, Nayef [106] provided an overview of the status of renewable energy technologies as part of an assessment of the potential utilization of renewable energy in Kuwait. Furthermore, Kuwait Petroleum Corporation is in the process of installing two PV systems and one low-temperature solar thermal system at selected locations within the premises of their operating companies (Personal communication). These systems will serve as pilot plants to assess the exact performance of these systems and their cost effectiveness, as an initial step prior to wider scale application. One main concern is the performance of these systems under ambient conditions of Kuwait, particularly the sand storms. Petrobel in Egypt powered the control system, safety systems, and radio link telecommunication systems for an offshore natural gas production platforms in the Mediterranean sea [107]. The main benefits that were pointed out are that there are increased reliability, and reduced cost and no moving parts. The reduction in cost is attributed to eliminating the need of laying power cables, step up/down transformers, and a fire-fighting system for a back-up fossil fuel power generator, as well as reducing the need for operators on the platforms for power generation. The aforementioned review of the role of oil and gas industry, particularly the international ones, in the development of renewable energy shows that this role passed through cycles of high interest and active involvement during past three decades. In a recent study, it was noted that the oil and gas industry has difficulties integrating solar PV technology in their energy supply chain, and the industry is in a trend to leave solar and concentrate more on fossil based fuels [108]. This is reflected by the level of investments in non-hydrocarbon by the US oil and gas industry, which is estimated at $1.5 billion, representing roughly 5% of the total industry and government investment of approximately $30.1 billion [109], mainly in non-conventional oil resources. Among the possible causes of this trend is the absence of policies that encourage the oil and gas industry to continue their support for renewable energy. Furthemore, the industry has other options to address the environmental impact of fossil fuels. Among these options are energy management, emissions trading, biofuels, and carbon capture and sequestration (CCS). Miller [110], using innovation theory, analyzed also the factors that led some oil companies to reduce their emphasis on solar businesses. He attributed that to the management models of these large corporations, concluding that these models with the dynamic rapid developments that have been taking place in solar innovation. This brief review of the role of the oil and gas industry demonstrated that the industry had a direct and a strong positive influence in the development of renewable energy technology and its applications. In addition to the contributions cited in this brief review, numerous other important contributions made by the companies cited in this section and other oil companies were

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not covered, since this is not the objective of this paper. However, it is clear that the oil and gas industry, with all its resources and depth of understanding of the energy sector, have a good potential in developing innovative renewable energy systems for industrial applications focusing on the specific needs of the oil and gas industry as demonstration cases.

6. The economics of utilization of renewable energy in the oil and gas industry As can be seen from the above review, the potential applications of renewable energy to meet the energy needs of the oil and gas industry is still in the R&D, pilot plant and demonstration, and economic feasibility assessment stages of development. Exceptions to this are few applications in isolated areas, where RE technology is economically justified. Reports on the economics of utilizing renewable energy to meet the needs of the oil and gas industry are still very limited. The feasibility of renewable energy technology in the oil and gas industry depends largely on the availability and price of natural gas, which is the main fuel used by the oil and gas industry to meet its energy needs. It also depends on the existence of infrastructures to transport natural gas for other uses, such as its use as fuel for power generation or as feedstock to the petrochemical industry. The economics also depends on the capital cost of the renewable energy systems, which has been decreasing gradually over the past few years. Nevertheless, some estimations made over the past few years are encouraging. For example, based on information provided by Glasspoint Solar Inc., Kovscek [41] reported that the levelized cost of solar generated steam is around $3/MMBtu. This was found to be very competitive in comparison with natural gas generated steam at the prevailing cost of natural gas in California, USA, over a period of 3 years from 2007 to 2010. Beath [111] assessed the potential of solar thermal energy in Australia and identified sites and industries where different technologies can be applied. Among these are applications for mining, ammonia production, oil refining and gas processing. Although, the use of solar energy in oil and gas industry is concluded to be presently unlikely, unless there is a carbon tax of sufficient magnitude to change this situation, there are possibilities for applications in remote locations, such as gas compression stations and partial input of solar thermal energy for preheating up to temperatures in the range of 160 to 280 1C. On the other hand, Kojima and Tahara [112] assessed the impact on the economics of refining crude oil to produce a higher percentage of high quality diesel through the introduction of a water electrolysis unit, powered by PV panels, to produce hydrogen. They found that the total CO2 footprint over the life cycle of the refinery was higher for PV-based hydrogen generation vis-à-vis hydrogen production by conventional procedures involving steam reforming of hydrocarbons. Hence, the route is considered both uneconomical as well as ecologically unacceptable until PV technology becomes more efficient and its cost is reduced substantially.

7. Future prospects of renewable energy in the oil and gas industry Transition towards renewable energy for the whole industrial sector has been recently reviewed. It was projected that up to 21% of total energy used by manufacturing can be of renewable origin, but mostly from biomass. The contribution of solar energy is projected to be only around 4% [4]. At present, projections on future prospects of renewable energy in the oil and gas industry can be only theoretically discussed due to lack of publications

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analyzing actual real operating RE systems in the industry. There are a number of constraints that are negatively impacting the penetration of renewable energy in the oil and gas industry. The main ones are: (a) The application of renewable energy to meet the energy needs of the industrial sector, particularly thermal energy, is limited and it is still under development. Extensive R&D effort is still required to develop reliable and stable thermal energy systems that can guarantee the continuous supply of energy throughout the day, to meet the needs of most industries. The intermittent nature of the solar energy makes it hard for the highly conventional industry to accept. The solar thermal technologies can be divided into 3 categories; High temperature (600–1000 1C), which can be achieved using parabolic dishes and tower, these technologies are more suitable for electricity generation. Medium temperature (250–600 1C), parabolic troughs and linear Fresnel technologies are used to provide direct steam for process heating or electricity generation as well. Finally the low temperature (o200), collectors such as evacuated tubes, advanced flat plate, and even flat plate can serve industry need for low temperature heat. All of these technologies are well developed. However, to meet the needs of the industry, thermal energy storage technologies should be further developed and their cost should be reduced to overcome the intermittent nature of solar energy. (b) The oil and gas industry have robust and reliable energy supplies that meet its energy requirements for different subsectors within the industry. These energy supplies are mostly by-products of the industry, such as associated gas and refinery gas. Thus, they are priced at relatively low value, which make them more economically viable in comparison with renewable energy. Therefore, energy transition towards renewable energy will be difficult to justify on the basis of economics alone in such cases. (c) The oil and gas industry is a well established industry with its own elaborate standards and best practices. However, solar systems are relatively new and require its manufacturers to make the solar processes compliant and compatible with the oil and gas industry. (d) Solar systems require large areas of land, which is something that downstream processing lacks. In refineries and petrochemical plants land tend to be very limited as most of the surrounding areas are reserved for fire, safety, security, and access for services and maintenance. Solar thermal systems will be difficult to install within the vicinity of the plants, and will loose efficiency if installed at remote distances. Despite the above mentioned constraints, which will continue to influence decisions concerning the use of alternative energy in the oil and gas industry for many years to come, gradual introduction of renewable energy is still a good possibility. The main applications in the short and medium terms of 10–20 years are electricity generation and steam production to meet the needs of the industry in remote and isolated locations. The most likely applications are: (a) The use of PV to generate power in remote and isolated locations. Electrical energy is used in the oil field for different applications, such as submersible pumps, water purification, water pumps, lighting, and other electrical applications. Submersible pumps are used for artificial lift in oil production, and water pumps are used for secondary oil recovery. Water desalination, using reverse osmosis, is sometimes required if fresh water resources are limited. In remote areas that have no access to power from the grid, their power requirements are

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Table 4 Comparison of solar photovoltaics [113].

Best cell efficiency Commercial module efficiency Area needed per kW Module cost

Units

Mono crystalline silicon

Poly-crystalline silicon

Amorphous silicon

Copper indium diselenide

Cadmium telluride

% % m2 $/Wp

24.7 15–19 7 o1.4

– 13–15 8 o1.4

10.4 5–8 15 0.8

20.3 7–11 10 0.9

16.5 8–11 11 0.9

often met using diesel generators. With today’s prices of solar PV, the economics are in favor of solar PV when compared with diesel generators. Different PV technologies can be employed in such applications (Table 4). However, some technologies will perform better than others depending on available land, and local environment. For example, in areas where land is limited, higher efficiency modules should be employed such as mono-crystalline, polycrystalline, or copper indium gallium selenide (CIGS) thin film modules. However, if land is not a limiting factor, the selection of the module type will be based on cost and track history. (b) The use of PV in the petroleum refining industry. The potential use of PV in the refining industry is limited, since the power loads are normally very high, and available land near refineries are normally limited. Nevertheless, the industry has an opportunity of using available space, such as rooftops and car parks to install PV technology supplement some of its electrical demand. Moreover, grid-connected PV system allows the installation of PV plant away from the refinery, on available land, and interconnects to the grid, which will transmit electricity to the refinery. (c) The use of CST technologies to meet the steam requirements for heavy oil recovery. As indicated in Section 1.1.2, heavy oil will play an increasing role in meeting world requirements of liquid fuels. Some heavy oil fields will require steam injection at a rate of approximately 5 T of steam per ton of oil. If the heat required to produce 1 T of steam is 3.38 GJ, then the energy required to produce 1 T of heavy oil is  17 GJ. Referring to Fig. 3, we can assume that steam assisted heavy oil production may easily reach 1 million barrel/day from regions suitable for CST technologies, such as the Middle East and South America. Then the amount of steam required is nearly 5 MT, and the total energy requirement is estimated at  85 PJ/day. The estimated CST plants that will be required to generate the needed steam will occupy an area of around 60 km2. The choice of solar heat in such an application is usually motivated by the limitation of suitable fuel for steam generation. This situation will either limit any increase in oil production, or oil producer will resort to using more valuable and more polluting fuel such as crude oil or fuel oil. Technologies that can be employed practically and that are commercially available include linear Fresnel and parabolic trough technologies. Both technologies can attain the required high temperatures (4500 1C). (d) The use of low and medium temperature solar heater systems for heavy oil processing at gathering centers. Heavy crude requires normally degassing, dewatering, and desalting near the production field before transportation to refineries. The crude oil needs to be heated to temperatures ranging between 50 and 150 1C. A number of solar technologies are available to meet the requirements of the processing conditions. This can also help free fuel resources for higher temperature processes. There are a number of solar heaters that are based on welldeveloped technologies, which enjoy higher efficiencies, as the temperature requirement is lower. The low temperature solar heaters include flat plate collector, and medium temperature

heaters include vacuum tubes collector, compound parabolic concentrator, and advanced flat plat. With low to medium systems, thermal storage is commercially available, which allows for more energy contribution to the total energy requirement. There are already a number of applications around the world that successfully integrated solar collectors for their industrial use. The oil and gas industry can extend such experiences to integrate solar collectors into its processes. It is worth mentioning that in 2012, solar heating plant with an area of 355 m2 was commissioned to supplement the heat requirement in throttling process of natural gas from the main gas pipeline into the local distribution network in Germany. In combination with utilizing biogas available onsite, the plant is producing 1000 MW h/year, which is approximately 80% of thermal energy demand. (e) Geothermal energy is another potential renewable energy that has a potential for growth in the oil and gas industry. Its usage will depend on locations, where high temperatures can be reached at reasonable depth. There is also a potential of utilizing geothermal energy using abandoned oil wells, when oil is nearly depleted. (f) In the time frame of over 20 years, there is a potential for using CST to supply energy to meet part of the heat requirements of heavy oil upgraders. Such upgraders, would normally be constructed close to areas where heavy oil is produced to improve the quality of the oil before transporting to refineries. It would be expected that some of these locations would be in isolated areas, where land is usually available for CST plants. Fig. 14 shows the levelized cost of energy for different technologies and for different regions. It shows clearly that PV and concentrated solar thermal technologies are significantly better than electricity generated from diesel in most regions. However, the graph compares concentrated solar power, which usually consists of parabolic trough, or linear Fresnel solar field that generate the necessary steam to drive the turbines for electricity production. For applications where high temperature heat is needed, we can eliminate the turbines and utilize steam directly. The system cost will drop by almost 30–40%. To sum up this section, we expect that the contribution of solar energy to the energy demand of the oil and gas industry reach around 5% of the total energy requirements of the industry up till 2035, and may reach 10% by 2050. This is partially based on previous studies concerning the transition towards renewable energy for the world industrial sector up till 2050 [3,4]. Based on these studies, the projected contribution of solar energy to the industrial sector is estimated to be around 4% by 2050. Our projection also takes into consideration the constraints and opportunities mentioned above. Our projections are higher than those predicted for the industrial sector because in our opinion the oil and gas industries are located in areas that are more suitable for solar technologies. We expect that solar energy applications by the oil and gas industry will be specifically favored in countries within the Middle East and North Africa region, which have significant oil and gas reserves, vast areas that can be utilized for solar plants, and high solar radiation. Based on these projections,

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Fig. 14. Typical levelized cost of energy ranges for renewable energy power generation technologies for 2012 [114].

the total amount of solar energy expected to be produced is estimated at around 2 PJ by 2035. Most of the solar energy expected to be produced will be thermal to meet the needs of the industry for steam for enhanced oil recovery and petroleum processing. We further expect that most applications will be within the up-stream industry.

8. Conclusions The application of renewable energy technologies to meet the needs of the oil and gas industry represents an emerging technological opportunity for the renewable energy industry. This opportunity will contribute to the efforts of the oil and gas industry in improving its environmental footprints, as well as save substantial amounts of hydrocarbon resources. It will also present an opportunity for the renewable energy industry to grow in an important segment of the industrial sector. As renewable energy technologies mature and their economics improve, it seems that the growth of their applications to meet the wide variety of energy needs of the oil and gas industry have a good potential to increase. Based on the review presented in this paper, the following conclusions can be made: (a) The drive for RE to meet the energy needs of the oil/gas sector is not only emerging technology but it is also a move within the stream of energy transition that the world is going through in all of its sectors. (b) The energy requirements for the oil and gas industry, which are currently estimated at nearly 10% of the total oil and gas produced, is in the range of 28 EJ (  700 Mtoe). The energy demand by the industry will increase in the future due to the increasing need for deploying secondary and tertiary recovery techniques for oil production, the higher energy required to process and refine heavy oils, and the need to abide by stricter environmental regulations related to the industry and the petroleum products it produces. Hence, the energy consumption by the industry is estimated to increase to at least 39 EJ by 2035. (c) A wide scope of applications of renewable energy, especially solar energy, within the oil and gas industries is starting to materialize, reaching the demonstration stage. These applications include large-scale PV power plants, as well as solar thermal-based steam plants.

(d) The application of solar energy by the oil companies is currently limited to upstream applications; however, downstream applications are likely to emerge in the future to meet the energy needs of the refining industry, particularly steam generation. Such applications in other processing industries are already in the demonstration stage. (e) The oil and gas industry and the scientific community must put more efforts to develop predictive methods to quantify the potential of the contribution of renewable energy to meet the needs of the oil and gas industry. The development of such predictive models will complement the efforts that are already being made by the refining industry to model its energy consumption with the objective of improving energy efficiency. (f) A number of solar based technologies that are still in the very early stages of their development have good potential for future commercial application. These include:  The desalination of waste formation water to produce freshwater suitable for agriculture or to meet oil production needs.  The production of hydrogen using various solar technologies, including solar based electrolysis and photocatalysis.  The gasification of various carbonaceous materials, including petroleum coke, waste material, and vacuum residue to produce syngas.  The use of photocatalytic reactors for industrial wastewater treatment, as well as treatment of gas emissions. (g) The direct role of oil companies in researching and developing renewable energy technologies is currently less intensive than the efforts made during the 1970s and 1980s. The current trend for the oil companies is to acquire, partner, or form alliances with specialized renewable energy companies that have effective and promising technologies, and support their strategic goals. The oil and gas industry has also been exerting concerted efforts to contribute to the development of relevant renewable energy technologies by establishing partnerships with emerging specialized companies in this field, verifying the performance of different technologies using demonstration-scale plants, and contributing to bridging the technology gap for full-scale commercial applications. (h) It is expected that the growth of the contribution of solar energy to the energy demand of the oil and gas industry will increase gradually over the next two decades utilizing the results of demonstration plants that are currently either in operation or in the planning phase. By 2035, solar energy is

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expected to contribute around 2 PJ, which represents around 5% of the total energy needs of the industry.

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