
==== Front
Heliyon
Heliyon
Heliyon
2405-8440
Elsevier

S2405-8440(24)13812-1
10.1016/j.heliyon.2024.e37781
e37781
Research Article
Environmental impact assessment of different power generation strategies in Oman: A comparative life-cycle analysis
Al Rashdi Zuhoor a
Barghash Hind hind.barghash@gutech.edu.om
a⁎⁎
Al Habsi Fahmi ab
Okedu Kenneth E. kokedu@academic.mit.edu.au
cd⁎
a Department of Engineering, German University of Technology, Muscat, Oman
b CC Energy Development S.A.L. (CCED), Muscat, Oman
c School of Information Technology and Engineering, Melbourne Institute of Technology, Melbourne, 3000, Victoria, Australia
d Department of Electrical and Electronic Engineering, Istinye University, Istanbul, Turkey
⁎ Corresponding author. School of Information Technology and Engineering, Melbourne Institute of Technology, Melbourne, 3000, Victoria, Australia. kokedu@academic.mit.edu.au
⁎⁎ Corresponding author. hind.barghash@gutech.edu.om
10 9 2024
30 9 2024
10 9 2024
10 18 e3778117 4 2024
28 8 2024
10 9 2024
© 2024 The Author(s)
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
This paper presents a comparative environmental impact assessment considering different power generation strategies in Oman. The Life-Cycle Assessment (LCA) methodology, and the OpenLCA tool, were employed in carrying out comprehensive analysis, and evaluation of the various environmental aspects in filling the research gap, by replacing conventional diesel generators with natural gas alternatives in Oman. The obtained results indicate that utilizing natural gas significantly reduces environmental impacts, including a decrease in global warming potential to 2.27 million kg CO2 eq, fossil fuel depletion to 34.5 million kg oil-eq, and ozone depletion to 0.13 kg CFC-11 eq. This study would help in policy decision-making to support a potential shift in power generation system, transitioning from the current use of diesel generator sets to flared produced Natural Gas across crude oil processing plants. Thus, mitigating operational cost, and improving efficiencies, for sustainable developments. Another salient part of this study is the implementation of more sustainable energy practices that supports the broader application of LCA in evaluating industrial environmental impacts. Furthermore, the results obtained in this work are in line with recent global climate change commitments and Oman's Vision 2040, in achieving cleaner energy sources to minimize environmental harm in the oil and gas sector.

Keywords

Life cycle assessment
Produced natural gas
Inventory analysis
Power generation
Deisel generator
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pmc1 Introduction

With population growth and industrial revolutions over the past decades, the increase in demand for energy has risen dramatically [1]. Fossil fuels like Coal, Crude Oil, and Natural Gas have been powering economies for over 150 years, and currently supply about 80 percent of the world's energy [2]. The dependency as a primary source of energy on fossil fuels have caused environmental impacts like air pollution, greenhouse gas emissions, and climate change [3]. This has driven interests toward innovative efficient ways of generating power from current conventional methods, as well as to find sustainable sources of energy like wind, solar and hydroelectric power [4].

In Middle East region, Oman is considered one of the main oil and gas producers, and its economy is highly driven on the oil and gas industry [5]. For this reason, oil and gas industries require substantial supply of energy to operate the oil and gas fields and processing plants. The fact is that most of the oil and gas fields in Oman are in rural areas and geographically distanced from each other [6]. Besides, there are number of oil and gas fields that do generate their electricity via diesel generators set [7]. This leads to elevated levels of greenhouse gases emissions and environmental impacts.

The increasing demand for electricity worldwide has led to an extraordinary expansion of the power generation industry over time. Oman vision is aimed to achieve net zero emissions and heavily rely on alternative energy sources by 2050 [8]. Diesel generators have conventionally been deployed for powering remote regions and serving as backup during blackouts [9]. However, their use comes with severe environmental impacts like air pollution, noise pollution and greenhouse gas emissions, increasing its shortcomings as an energy source [10].

As a result, there has been a growing interest in exploring alternative power generation options that are more environmentally friendly and cost-effective [11]. Natural gas is increasingly considered a promising option due to its lower emissions compared with other fossil fuels especially Diesel [12]. Its primary constituent methane is known to burn cleanly, producing minimal harmful by-products that are less harmful to the environment [13].

The introduction section of this paper considers several important questions such as; What are the specific benefits of natural gas as a cleaner energy source compared to diesel? What are the environmental challenges associated with the use of diesel generators in remote oil and gas fields? How can Life Cycle Assessment estimate the environmental impact of each process? The answers to these questions will provide a comprehensive understanding of the potential for natural gas as a cleaner alternative, especially in the context of Oman's oil and gas industry based on climate commitments.

2 Literature review

2.1 Comparison of diesel and natural gas for power generation

The oil and gas sector has been assessing and contrasting the utilization of natural gas and diesel for power production [14].

Elgohari and Sedik compared the efficiency and effectiveness of natural gas and diesel fuel oil in gas turbine-powered ships [15]. The study concluded that Natural Gas turbine-powered ships emit less Carbon Dioxide, Nitrogen Oxides and Sulphur Oxides compared to Diesel-powered ships. In other words, engine types powered by a Natural Gas turbine use less energy than Diesel fuel with low power and high fuel consumption due to low density. The authors also emphasized the importance of proper engine design and maintenance to improve efficiency and emissions for both fuel types.

Azad et al. presented a study on the performance, emission, and combustion characteristics of a diesel engine fuelled with macadamia and grapeseed biodiesels [16]. The study conducted by the researchers involved a comparison of engine performance and emissions of macadamia and grapeseed biodiesels with conventional Diesel fuel. The study revealed that both biodiesels exhibited similar performance characteristics as Diesel fuel, but with reduced emissions of Particulate Matter and Carbon Monoxide. However, the Nitrogen Oxide emissions were slightly higher in both biodiesels when compared to Diesel fuel. Based on their findings, the authors of the paper concluded that macadamia and grapeseed Biodiesels possess promising potential as a sustainable and renewable substitute for Diesel fuel in diesel engines, with significantly lower levels of harmful pollutants.

Cho and Strezov provided a comparative review of the environmental impacts of combustion-based electricity generation technologies [17]. The authors focused on the previous life cycle assessment studies for different technologies and their eutrophication impacts. Coal-fired power generation, Natural Gas power generation, Thermal-based power generation, and Biomass power generation are the technologies that were included in the study. This study provided a deep analysis of the environmental impact from these power generation technologies, and also proposed ways for these power generation technologies to become more sustainable energy sources.

Silveira et al. compared the environmental and economic performance of a combined cycle power plant with that of one thousand diesel power plants of 1 MW [18]. The study revealed that the combined cycle power plant is more environmentally friendly and economically feasible when compared to Diesel power plants. The combined cycle power plant emits fewer pollutants and has higher ecological efficiency. While the initial investment is high, it has low operating costs and energy efficiency, reducing the overall cost of ownership so that if consumed with an integrated power plant application, it can have significant environmental and economic benefits compared to diesel electric generators.

2.2 Life cycle assessment (LCA)

Life Cycle Assessment (LCA) is a method used to evaluate the environmental impacts of products, processes, or technologies quantitatively throughout the different phases of their life cycles [19].

LCA is a widely utilized methodology for assessing the environmental implications of a product or system throughout its entire life cycle, encompassing everything from raw material extraction to final disposal [20]. In the context of the crude oil production sector, LCA has been employed to evaluate the environmental impact of various power generation alternatives, including diesel and natural gas [21].

LCA study is conducted to compare natural gas and crude oil in PT Pertamina Hulu Mahakam - Bekapai Senipah Peciko site [22]. The primary goal of this research was to assess the environmental implications of diesel and natural gas in terms of global warming, ozone depletion, and eutrophication. To acquire complete results, the research collected data from many phases, including transportation, energy generating, and oil and gas production. The study showed that although natural gas has lower Global Warming Potential (GWP) and Ozone Depletion (ODP) impacts than crude oil, it has higher Eutrophication Potential (EP) impact due to nitrogen oxide (NOx) emissions from combustion of natural gas. The authors in Ref. [22] PT Pertamina case study advises adopting NOx reduction to further reduce the environmental impact of natural gas plants.

Environmental impact assessment of crude oil is conducted using LCA [23]. The authors carried out the study in Indonesia to investigate the activities of crude oil exploration and its impact on the environment, covering the complete cycle of the exploration activities. The data collection for this study covered the extraction, transportation, and processing. SimaPro software was used for social analysis to assess the environmental characteristics of each phase. The study found that the environmental impacts on global warming, acidification, fossil fuel depletion are significant due to drilling and extraction phases of crude oil exploration. The study recommended that companies should shift to renewable energy as steps to reduce environmental impact.

A comparative life cycle assessment of diesel and compressed natural gas (CNG)-powered refuse collection vehicles has been implemented in a Canadian city [24]. The aim of the study is to identify the environmental impacts associated with different types of fuels and to see which ones are more sustainable. The authors applied the ReCiPe methodology to measure the environmental impacts of fuels throughout their life cycle, including vehicle extraction, transportation, finishing, operation, and maintenance The study found that vehicles powered by CNG achieves low environmental impact in all categories except photochemical oxidant production. The CNG powered vehicles were found to emit lower particulate matter and nitrogen oxides which resulted in lower carbon footprint, compared to vehicles powered by diesel. The assessment of environmental impacts of CNG powered vehicles and diesel-powered vehicles was assessed by performing a sensitivity analysis which was part of this study. This analysis considered variations in fuel prices and vehicle fuel efficiency to determine their influence on the overall impact. The authors of the paper examined multiple studies that investigated the LCA of various power generation technologies, including thermal methods such as coal-fired power plants, natural gas power plants, and biomass combustion. Their investigation also examined the potential effects on eutrophication and the economic and policy implications tied to these technologies. This comprehensive study provides valuable insights into the environmental impacts of power generation methods based on combustion and their potential contribution to building a more sustainable energy system.

An environmental performance for standby diesel generator set is preformed through implementing LCA [25]. The energy consumption and greenhouse gas emissions of the generator's complete life cycle was evaluated using LCA tool. The study revealed that the diesel consumption and emissions of greenhouse gas from the generator's operation were almost negligible. The study further suggested that employing alternative energy sources, such as solar or wind energy, could effectively mitigate the environmental footprint of standby power generation.

An overview on the LCA is provided for electricity generation technologies: Overview, comparability, and limitations, examining the environmental impacts of multiple electricity generation technologies [26]. The authors considered each electricity generation technology's entire life cycle, from raw material extraction to disposal. A review of different electricity generation technologies, including coal-fired power plants, nuclear power plants, and wind turbines, was included in the study. The authors stressed the requirements for LCA methodology standardization in order to enhance comparability and guarantee transparency. Researchers and decision-makers interested in assessing the environmental performance of electricity generation technologies can learn a lot from the study.

Gasoline and diesel fuel are studied and compared through life cycle analyses (LCAs) [27]. The study revealed that diesel and petrol have a significant impact on the environment. Diesel is severely affected by its high carbon content and the emission of particulate matter and harmful oxides of nitrogen. It should be noted that LCAs may produce different results, depending on the functional group, system constraints, and resource allocation method. The authors concluded that further research is needed for LCAs comparative and reliable assessments for the effectiveness of these fuels. Furthermore, sustainable alternatives to gasoline and diesel must be identified.

LCA is provided for three different fuel technologies for bus transport systems: diesel, natural gas, and hydrogen fuel cells [28]. The study showed that all three technologies have different levels of environmental impact, with Hydrogen fuel cell buses having the least and Diesel buses having the most. Diesel buses produce the most greenhouse gases, while Natural Gas buses produce more Oxides of Nitrogen. But Hydrogen fuelled buses, overall, have much lower emissions. Studies showed that Hydrogen fuelled buses can significantly reduce the environmental impact of public transportation systems. Nevertheless, the cost and infrastructure remained a challenge as highlighted by the authors. This study has provided deep insights of the different fuel technologies in the transportation sector when it comes to the environmental impacts and was recommended for further studies and developments.

The performance of a diesel engine running on diesel and natural gas in dual-fuel mode of operation has been investigated [29]. The performance of the engine was evaluated by testing it at different loads and Natural Gas substitution rates. This evaluation was based on three parameters, namely brake power, specific fuel consumption, and thermal efficiency. The study revealed that the brake power of the engine increased with an increase in Natural Gas substitution rate. Additionally, the specific fuel consumption and thermal efficiency of the engine also improved. The study also analysed the engine's emissions of NOx, CO, and HC. It was found that NOx emissions decreased with an increase in Natural Gas substitution rate, while CO and HC emissions increased. The authors proposed the use of Natural Gas in dual-fuel mode to enhance the engine's performance and reduce its environmental impact.

Electricity and its environmental impacts are evaluated for fuel switching [30]. The authors organized a comparison analysis of emission between Coal and Natural Gas, Oil and Natural Gas in terms of Carbon Dioxide (CO2), Nitrogen Oxides (NOx), and Sulphur Dioxide (SO2) emissions. The findings revealed significant reductions in emissions when switching to Natural Gas. Specifically, substituting Natural Gas for coal led to a remarkable decrease in CO2 emissions by 43 %, NOx emissions by 80 %, and SO2 emissions by 99 %. Similarly, when replacing Oil with Natural Gas, there were notable reductions in CO2 emissions by 27 %, NOx emissions by 88 %, and SO2 emissions by 100 %. The study also emphasized on the potential of Renewable Energy sources as viable alternatives to fossil fuels for power generation and a credible option to reduce the environmental impact.

A comprehensive review and comparison of recent optimization methodologies used has been provided for diesel engines and diesel power generators [31]. The article focused on various ways to improve Diesel engine and generator performance. The methods discussed include the use of mathematical models, artificial neural networks, genetic algorithms, and particle swarm optimization. The focus of this study was to review the applied technologies that resulted in greater fuel efficiency and engine performance, plus reduction in emissions. The authors summarized the article by suggesting areas for further research in this field.

Electricity generation and emissions have been reviewed in Indonesia from 1987 to 2009 [32]. The study analysed data collected from the Indonesian power sector and identified changes in electricity generation and emissions in a certain time considering the availability of coal. The study illustrated that the great demand in power sector, resulted in an increase in Greenhouse Gas emissions. The authors recommended that the regulators in Indonesia should adopt and demonstrate the use of sustainable strategies for energy efficiency to reduce the environmental impact from the energy generation sector.

A review of diesel to gas engine power plant conversions has been presented, with focus on the technical aspects of the conversion process [33]. The authors outlined the reasons for the conversion, including environmental issues and economic considerations, and discuss the conversion process in detail, including selection of appropriate gas engines, gas supply systems, and other equipment. Based on a case study of an existing Diesel engine power plant, the report also gives an initial blueprint for an operating power plant. The authors concluded that changing Diesel engines to Gas engines is a practical and efficient strategy to reduce emissions and enhance efficiency while giving economic benefits to power station owners.

The emissions of a diesel generator fuelled system have been compared with Biodiesel and fossil Diesel fuels [34]. The experiment was carried out on a 5-kW Diesel generator under various load circumstances. When compared to fossil Diesel fuel, Biodiesel produced fewer emissions of Carbon Monoxide, Hydrocarbons, and Particle Matter. However, Biodiesel has slightly higher NOx emissions. As a result of the conclusion drawn from this paper, it was found that Diesel generators fuelled by Biodiesel produced lower emissions compared to Diesel generators that are fuelled by Diesel. Yet, further research is needed to optimize the combustion process to reduce the emissions of nitrogen oxides.

In light of the above, after conducting preliminary research, it became apparent that there is a gap in specific studies focusing on the LCA related to the replacement of diesel generators with natural gas alternatives in Oman. Consequently, this study is designed to delve into the environmental impacts associated with the operation of diesel generators within an oil block in Oman. Furthermore, it aims to analyse how the potential transition to natural gas could offer improvements in the environmental performance of the selected block over time. It is worth noting that this investigation will prioritize environmental considerations, with economic factors being excluded from the scope of this study.

3 Life cycle impact analysis

The objective of this study is to carry out a comparative study between two power generation options for Crude Oil Production from producer wells in the fields, to the processing of the crude oil at the plants, in an Oil Block in Oman. The comprehensive comparison analysis covers the environmental and economic aspects of the current method of generating the power – conventional – which is by using diesel generators set, and the proposed method of generating power in a sustainable way by utilizing the by-product of the Crude Oil production in this process; Natural Gas – to generate the required electricity instead of flaring the produced Natural Gas.

This study can be generalized, as the inputs to the LCA software were inputs and outputs of these five plants as illustrated in the Appendix table.

3.1 Study area

An Oil Field located in central eastern part of Oman as shown in Fig. 1-a, referred to as “Block” to maintain confidentiality, is the study area for this research. Fig. 1-b illustrates the Block plants and fields integration of each other. The Block is operated by an Oil Company that was granted permission from the Ministry of Energy and Minerals in Oman. The concessional permits for this block has a total area of 29,127 m2.Fig. 1 (a). Location of the selected oil block in Oman. (b). Block plants and fields schematic plot.

Fig. 1

The block consists of five oil processing plants that are responsible for the processing, production, and exportation of Crude Oil. Each plant receives the Oil flow from a dedicated field from a number of oil producer wells. These wells are equipped with Electrical Submersible Pumps (ESPs) that extract a fluid mixture consisting of crude oil, water, and natural gas from the reservoirs. The extracted fluid mixture is then transported to the respective oil processing plant. The primary focus of this study is to analyse the power generation options employed in the Oil Block in order to study the LCA for evaluating the environmental impacts. The goal of conducting the LCA is to conduct a comparative analysis of the environmental impacts associated with power generation using diesel versus natural gas in order to supply electricity to the processing plant and the oil producer wells equipped with electrical submersible pumps in the entire Block. This study aims to provide insights into the environmental consequences of the two power generation options under consideration.

The company selected for this case study operates an Oil and Gas block in Oman, where five plants were built across the block to produce the Crude Oil. Each of these five plants require means of source of energy. The current source of energy is via Diesel Generator sets. The proposed source of energy is a centralized power generation plant via Produced Gas (Natural Gas), out of these five plants. Some of these plants do not produce enough gas in order to generate the required power. Thus, the proposed energy source was a centralized power plant to generate and supply power back to these five plants.

3.2 Process description

The five Crude Oil processing plants in this study, differ in their mode of operation, respective capacities, and the fields to which the Oil producer wells are connected in each plant. The main strategy for the five plants is that the crude oil processing scheme utilizes ESP powered by Diesel generator sets at the oil producer wells to transport fluid for further processing. Upon reaching the plant, gross fluids undergo separation into crude oil, produced water, and produced gas using three-phase production separators. The process of gas handling and separation is a conventional method like any process in upstream Oil & Gas industry that consists of 3-phase production separators, fuel gas scrubbers, and knock-out drums. The process does not include gas purification as the gas engines to generate the power can handle it without further purification and treatment.

Crude oil is processed in heater treaters, and associated produced water is treated to remove oil contents. Produced gas serves various purposes, including fuel gas supply and crude oil tank blanketing, with excess and sour gas burned at low and atmospheric pressure flares. The gas emissions will remain constant without any changes as the production profiles of gas at each plant will remain the same for the period covered in this case study without any introduction of new Oil & Gas fields and production profiles. As a backup plan, diesel engines for power generation are kept for emergency cases to supply power for temporary measures until the process variables are brought back to normal operating conditions.

The gas produced from the five plants covered in this case study are from development fields – matured reservoir – with known crude oil chemistry and gas compositions. There is no consideration of new fields i.e. appraisal nor exploration fields that might introduce a different crude oil chemistry or gas compositions.

The fundamental processes and equipment used in Oil and Gas processing facilities – in the upstream industry – are standardized globally. The core function of any processing facility is to separate the extracted gross fluid from the reservoir into three basic components: Crude Oil, Produced Water, and Produced Gas. This separation is carried out via standardized processing units with variation only in capacities and energy requirements based on the scale of the operation, but the fundamental technology and processes remain consistent. Given this standardization, this research results can be applied to similar Oil & Gas processing plants and as well can be generalized in terms of energy use, economic feasibility, and environmental impacts.

A detailed comparison of the five plants is provided in the Appendix. Table 1 provides the comparison of the key numerical performance index of the five considered plants.

The system boundary and the inventory description for each plant is explained as follows.

3.2.1 - Plant 1

From Fig. 2, fluid from numerous oil producer wells is transported to a crude oil processing plant, where it undergoes separation into crude oil, produced water, and produced gas using phase production separators. The separated crude oil is further treated in heater treaters, stored in tanks, and then transferred to Plant-3. Produced water is treated to remove oil contents and injected into multiple produced water injection wells, with emergency routing to an evaporation pond. The remaining produced gas is used for fuel gas supply and crude oil tank blanketing, while excess gas is burned at low pressure (LP) and atmospheric pressure (AP) flares. Power for the processing plant is generated by four diesel generator sets within the facility.Fig. 2 Plant-1 crude oil processing plant - system boundary.

Fig. 2

3.2.2 - Plant 2

Fluid from oil producer wells is transported to a processing plant. The separated crude oil is further treated in a dual-fuel heater treater. The associated produced water is treated to remove oil contents. The remaining produced gas is used for fuel gas supply and crude oil tank blanketing. Stabilized crude oil is stored before transfer. The water treatment facility employs American Petroleum Institute (API) separators to remove crude oil traces from the produced water, redirecting separated crude for further processing. The Produced water is injected into wells, with emergency routing to an evaporation pond, as shown in Fig. 3. Various chemicals, including demulsifier, oxygen scavenger, scale inhibitor, and corrosion inhibitor, are used. The power for the processing plant is generated on-site.Fig. 3 Plant-2 crude oil processing plant - system boundary.

Fig. 3

3.2.3 - Plant 3

The stabilized crude oil is stored in two storage tanks before being transferred to the customer selling point (FMS) through a 16″ pipeline. The water treatment facility incorporates three API separators to eliminate any traces of crude oil from the produced water. The separated crude is redirected to an off-spec tank for further processing in the production separators. The Produced water is injected into two produced water injection wells using five injection pumps. In emergency situations, the Produced water is temporarily routed to an evaporation pond until normal conditions are restored. Various chemicals, including demulsifier and defoamer, are injected into the Produced water stream. Additionally, corrosion inhibitor and H2S scavenger are injected at the crude oil export point and Produced water injection header. The power required for the entire processing plant is generated by three diesel generator sets located within the plant (see Fig. 4) .Fig. 4 Plant-3 crude oil processing plant - system boundary.

Fig. 4

3.2.4 - Plant 4

The stabilized crude oil is stored in small tanks before being transferred to Plant-3. The water treatment facility employs two API separators to remove any crude oil traces from the Produced Water, redirecting separated crude for further processing. The Produced Water is injected into five wells using two injection pumps, with emergency routing to an evaporation pond until normal conditions are restored. Various chemicals, including demulsifier for the Produced Water stream and corrosion inhibitor at the Crude Oil export point and Produced Water injection header, are used. The power for the entire processing plant is generated by three Diesel Generator sets on-site (see Fig. 5).Fig. 5 Plant-4 crude oil processing plant - system boundary.

Fig. 5

3.2.5 - Plant 5

Stabilized crude oil is stored in nine small tanks before being transferred to Plant-3. The water treatment facility, featuring two API separators, removes any crude oil traces from the Produced water. Separated crude is redirected for additional processing in production separators. The Produced water is injected into five wells using two injection pumps, with emergency routing to an evaporation pond as needed. Various chemicals, including demulsifier for the Produced water stream and corrosion inhibitor at the crude oil export point and Produced water injection header, are employed (see Fig. 6).Fig. 6 Plant-5 crude oil processing plant - system boundary.

Fig. 6

3.3 Inventory analysis

Accurate inventory prediction is crucial for effective safety management and goods inventory. It helps to improve production efficiency for enterprises and is vital for optimizing supply chain performance and cost control [35].

In LCA, the inventory analysis stage is crucial for gathering all the pertinent information [36]. In this stage, the data on mass and energy flows pertaining to the Crude Oil Processing Plants were physically collected at the five plants and fields within a specific period (from March 1, 2022 to April 30, 2022). Obtaining reliable and comprehensive data is a significant component of any life cycle analysis. The quality of the data collected has a direct influence on the accuracy and reliability of the results generated by an LCA tool.

In this particular study, substantial effort and time were dedicated to collecting real-time data from various stages of the Crude Oil production life cycle at these plant facilities, including historical data from the year 2022. The inputs and outputs of mass and energy represent the actual flows within the system, encompassing parameters such as rotating equipment, chemical injection rates, and other relevant factors.

Furthermore, the assessment of inventory flow in crude oil production across the five plants, where diesel generators serve as the primary means for both mass and energy flow, can be found in the Appendix. The power generated by using diesel and the power generation using collected flare gas must meet the demand of total power requirements. The difference between the two methods of generating power was not the scope of this study. Yet, the consumption of diesel in litres, the number of diesel engines to generate the power and the details of power requirements at each plant are provided in the Appendix. In summary, the power requirement is 106.95 MW.

This analysis encompasses a detailed examination of the processes involved in the transfer and management of energy throughout the production cycle, providing insights into the specific dynamics and interdependencies within each plant's energy flow system.

The ReCiPe (Renewable Energy and Carbon Footprints for Water and Waste) is a life cycle impact assessment (LCIA) method that provides midpoint indicators to assess environmental impacts across various categories. In this study, OpenLCA, was used with ReCiPe midpoint method to analyse the potential environmental impacts associated with production of crude oil by using diesel generators and natural gas. This approach allows for a more comprehensive understanding of the sustainability and environmental performance of a given system. The results obtained from this analysis can be valuable for decision-making, product design improvements, and overall environmental management.

4 Results

This section aims to present the findings of a comparative study in evaluating the use of diesel generators and natural gas power generation in the studied Oil Block, focusing on environmental considerations. The objective is achieved through the implementation of LCA, offering valuable insights into parameters such as greenhouse gas emissions, and energy consumption rates, associated with each power generation method. This approach provides a comprehensive overview of their overall environmental impact.

Impact analysis is a way of studying the environmental effects of any process. Several environmental effects were studied, constituting 18 environmental impacts from OpenLCA software [37]. As the process of gas collection and separation is a conventional method and not further to purification process, the gas used for power generation impact categories were limited. In this study, three specific impact categories were chosen for detailed analysis to compare the results between the two power generation options, as they directly relate to environmental emissions in the oil and gas Industry. These selected categories play a crucial role in decision-making regarding the optimal power generation option, while acknowledging the significance of the remaining 18 impact categories Table 1.

The three selected impacts are climate change (GWP), fossil fuel depletion (FDP), and ozone depletion (ODP) as shown in in Table 2 and Fig. 6.Table 1 Comparison of the key numerical performance index of the five considered plants.

Table 1	Plant-1	Plant- 2	Plant- 3	Plant- 4	Plant −5	
Energy Consumption (kWh)	15.93×105	12.09×104	31.48×104	22.17×104	10.08×104	
Diesel Consumption (l/d)	40,181.251	7200	18,850	13,200	6000	
Gross Fluid Handling (m3/d)	5737.48	2761.57	3588.31	2392.81	1703.45	
Waste Gas (Flared)
(Sm3/d)	34,495.86	336,963.22	104,702.42	178,214.47	26,472.25	
Crude Oil (Product) (m3/d)	2042.87	1268.86	809.047	847.832	572.406	

Table 2 Results for the five plants using two power generation options, D = Diesel, and NG = Natural Gas.

Table 2Scenario	Plant-1	Plant-2	Plant-3	Plant-4	Plant-5	
D	NG	D	NG	D	NG	D	NG	D	NG	
Global Warming Potential	8.9E+09	2.1E+04	8.8E+11	1.1E+05	2.7E+11	2.2E+05	4.6E+11	1.4E+05	6.9E+10	8.3E+04	
Fossil Fuel Depletion	4.1E+09	5.6E+06	3.9E+11	2.8E+06	1.2E+11	3.6E+06	2.1E+11	2.4E+06	3.1E+10	1.7E+06	
Ozone Depletion	5.6E-02	1.1E-03	1.4E-02	5.8E-03	3.0E-02	1.2E-02	1.1E-02	4.6E-03	1.3E-01	1.3E-01	

Table 3 shows the impact categories for climate change in both power generation options, and Fig. 7 shows the total amount of GHG emissions generated from the two scenarios.Table 3 The impact categories for climate change in both power generation options.

Table 3Flows	Plant 1	Plant 2	Plant 3	Plant 4	Plant 5	
Scenario	D	NG	D	NG	D	NG	D	NG	D	NG	
Total amount =	8.97E+09	2.06E+04	8.77E+11	1.06E+05	2.72E+11	2.19E+05	4.64E+11	1.38E+05	6.89E+10	8.32E+04	
Carbon Dioxide (CO2), fossil	8.95E+09	1.85E+04	8.74E+11	9.25E+04	2.72E+11	2.00E+05	4.62E+11	1.27E+05	6.87E+10	7.57E+04	
Methane (CH4), fossil	–	2.06E+01	–	1.07E+02	–	2.22E+02	–	1.41E+02	–	8.40E+01	
Dinitrogen Monoxide (N2O)	–	4.09E-02	–	2.13E-01	–	4.41E-01	–	2.79E-01	–	1.67E-01	

Fig. 7 The total amount of GHG emissions generated from the two scenarios.

Fig. 7

Table 4 outlines the impact categories for fossil fuel depletion in both power generation options, while Fig. 8 illustrates the total amount of fossil fuel depletion generated from the two scenarios.Table 4 Impact categories for fossil fuel depletion in both power generation options.

Table 4Flows	Plant 1	Plant 2	Plant 3	Plant 4	Plant 5	
Scenario	D-P1	NG-P1	D-P2	NG-P2	D-P3	NG-P3	D-P4	NG-P4	D-P5	NG-P5	
Total amount	4.06E+09	5.61E+06	3.96E+11	2.75E+06	1.23E+11	3.62E+06	2.10E+11	2.41E+06	3.11E+10	1.69E+06	
Crude Oil in ground	–	5.38E+06	–	2.59E+06	–	3.37E+06	–	2.24E+06	–	1.58E+06	
Natural Gas in ground	3.65E+09	–	3.57E+11	4.74E+04	1.11E+11	9.82E+04	1.89E+11	6.22E+04	2.80E+10	3.71E+04	

Fig. 8 The total amount of fossil fuel depletion generated from the two scenarios.

Fig. 8

Representation of the major sources of ODP impacts between the two power generation options are in Table 5.Table 5 The major sources of Ozone Depletion impact between the two power generation options.

Table 5Flows	Plant 1	Plant 2	Plant 3	Plant 4	Plant 5	
Scenario	D-P1	NG-P1	D-P2	NG-P2	D-P3	NG-P3	D-P4	NG-P4	D-P5	NG-P5	
Total amount	5.6E-02	1.1E-03	1.4E-02	5.8E-03	3.0E-02	1.2E-02	1.1E-02	4.6E-03	1.3E-01	1.3E-01	
Methane Bromo Chloro Di-Fluoro	–	1.5E-04	–	8.0E-04	–	1.6E-03	–	6.2E-04	–	1.1E-02	
Methane Bromo Chloro Tri-Fluoro	9.1E-03	1.3E-05	1.1E-03	6.4E-05	2.5E-03	1.3E-04	9.0E-04	5.1E-05	1.5E-02	4.7E-03	

5 Discussion

This section aims to discuss and explain the findings of the results for the three environmental impacts which are climate change, Fossil Depletion, and Ozon depletion.

5.1 Climate change

Climate change is an environmental consequence that involves alterations in long-term temperature patterns and weather conditions. It encompasses global warming, which is attributed to the release of GHGs into the atmosphere [38]. Climate change is directly associated with the carbon footprint, which represents the cumulative GHG emissions resulting from a particular process. To mitigate its impact, it is crucial to identify the primary sources of emissions within the process [39]. In terms of their respective impacts on climate change, Natural Gas power generation emerges as the less significant impacts when compared to Diesel power generation. This difference arises primarily due to the Carbon Dioxide (CO2) emissions between the two fuels when burnt; with Diesel fuel discharging higher CO2 amounts into the atmosphere compared to Natural Gas due to their predominant compounds as shown in Fig. 7.

5.2 Fossil depletion

Fossil fuel depletion refers to the diminishing availability of fossil fuels in the future due to their extraction for various purposes such as fuel and energy production, as well as the production of inputs like mineral fertilizers [38]. The extraction of crude oil, hard coal, and natural gas carries external costs for society since it reduces the overall stock of these resources, affecting both present and future generations [38].

In Fig. 8, the analysis presents thetransitioning from diesel-based power generation to natural gas-based power generation, with a significant reduction in fossil fuel depletion. This reduction owes largely due to the utilization of produced natural gas which is a valuable by-product from Crude Oil production activities. In the conventional power generation method, this valuable resource is flared as a waste product, resulting in substantial loss of resources. By adopting this energy source strategy, would not only optimize resource consumption, but also advance the overall durability of our energy infrastructure.

5.3 Ozone depletion

The stratospheric ozone layer plays a crucial role in absorbing a significant portion of the harmful Ultra Violet radiation emitted by the sun [38]. In its natural state, ozone is constantly being formed and depleted. However, certain artificial chemicals containing fluorine, bromine, and chlorine groups, known as Ozone Depleting Substances (ODS), can significantly accelerate the rate of ozone destruction, resulting in the thinning of the ozone layer [38].

In terms of how they impact the Ozone layer, Diesel power generation has a larger effect compared to Natural Gas power generation. The reason for this lies on how diesel combustion leads to Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs) emissions.

As opposed to Diesel fuel burning, using Natural Gas produces fewer Nitrogen Oxides (NOx) and VOCs. Thus, having less of an impact on forming smog or ground level Ozone. It is worth noting however that even though Natural Gas may be better in some regards with its lower emissions output, its extraction methods and infrastructure activities could leak potent greenhouse gases like methane which ultimately contribute towards climate change. An indirect factor which could affect our planets complex relationship between Climate Change and the Ozone layer is shown in Fig. 9.Fig. 9 The major sources of Ozone Depletion impacts between the two power generation options.

Fig. 9

The potential shift in power generation system, transitioning from the current use of diesel generator sets to flared produced Natural Gas has influential societal values. It introduces a cleaner source of energy, which has direct health benefits for communities living near the oil field. The social assessment that was implemented in Lindi region shows that the community agreed and support the local authorities in implementing natural gas as a source of energy since it is more effective; and the natural gas can operate the implemented projects that can support the educational and health sectors [40]. The obtained results indicate that utilizing natural gas significantly reduces environmental impacts, including a decrease in global warming potential, fossil fuel depletion, and ozone depletion. As per other studies, natural gas and diesel generators in the transportation sector show the Well-to-Wheel (WTW) LCA method. This scheme was implemented for bus transport, and it was found that diesel generates higher greenhouse gas emissions and water consumption than natural gas [41]. Eventually, this power shift contributes to better air quality and public health outcomes. In another aspect, the development of power generation utilizing the Produced gas from the plants supports job creation opportunities during the phases of the power plant development; from construction to operation of the plant, uplifting the workforce skills in this field and provides a value for long term economic growth, which is in line with global commitments based on the Sustainable Development Goals (SDGs) [42].

6 Conclusion

In conclusion, this study focused on the critical importance of evaluating and analyzing environmental impacts when selecting power generation options. By implementing Life Cycle Assessment (LCA), the study found that using Natural Gas in Oman produced a by-product of crude oil; provides significant environmental benefits compared to the current use of diesel generators, notably reducing greenhouse gas emissions and mitigating fossil and ozone depletion. Practically, the results indicate that utilizing natural gas significantly reduces environmental impacts, including a decrease in global warming potential to 2.27 million kg CO2 eq, fossil fuel depletion to 34.5 million kg oil-eq, and ozone depletion to 0.13 kg CFC-11 eq., which confirms that Oman should consider transitioning to Natural Gas for power generation to achieve cost savings, and operational efficiencies, for sustainability. As this is an innovative technology in Oman, theoretically this research study found that understanding of energy sustainability can offer empirical evidence of Natural Gas's environmental advantages over diesel. In the contribution of the theoretical and the practical implications of this work, this study would enhance and improve the existing literature by implementing more sustainable energy practices and supporting the broader application of LCA in evaluating industrial environmental impacts. Overall, the research highlights the value of adopting cleaner energy sources to minimize environmental harm in the oil and gas sector.

For future work, it is important to investigate and improve the comparative environmental performance of sustainable energy sources, particularly photovoltaic (PV) panels, in contrast to diesel generators and natural gas. The PV industry is mentioned as a critical component of China's strategy for targeting carbon neutrality [43], considering its significance in the broader context of Environmental, Social, and Governance (ESG) frameworks. Accordingly, Oman's geographical location, with its high solar irradiance, would lead to high energy production effectively, through the potential of PV technology [44]. Integrating a comparative analysis of PV technology with the conventional energy sources, such as diesel generators or with the alternative sources like natural gas, will provide a comprehensive understanding of their respective impacts on carbon emissions and overall sustainability.

Data availability

The data used for this research would be made available by the authors upon request.

CRediT authorship contribution statement

Zuhoor Al Rashdi: Writing – original draft, Validation, Software, Methodology, Investigation, Formal analysis, Data curation. Hind Barghash: Writing – original draft, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization. Fahmi Al Habsi: Software, Methodology, Investigation, Formal analysis, Data curation. Kenneth E. Okedu: Writing – review & editing, Investigation, Formal analysis, Data curation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix Name	Location	Plant-1	Plant- 2	Plant- 3	Plant- 4	Plant −5	
Heater Treater	Downstream of Oil Separators	12.816×103	12.816×103	25.632×103	10.68×102	12.816×103	
Oil Booster Pumps	Downstream of Oil On-Spec Tank	28.8×101	28.8×101	5.40×102	1.92×102	3.6×102	
Oil Export Pumps	Downstream of Oil Booster Pumps	10.8×103	10.8×103	25.56×103	5.28×103	5.28×103	
Crude Off-spec Pumps	Downstream of Oil off-spec Tank	–	–	5.28×102	–	–	
PW Booster Pumps	Downstream of PW Storage Tanks	–	–	6.72×102	–	–	
PW Feed Pumps	Downstream of PW API Tanks	10.8×102	10.8×102	–	–	–	
PW Injection Pumps	Downstream of PW Booster Pumps	21.6×103	21.6×103	15.6×103	17.904×103	17.904×103	
Deformer Injection Skids	Oil Export Header & PW Injection Header	2.64×101	2.64×101	1.2×101	1.2×101	1.2×101	
Demulsifier Injection Pump Skids	Inlet Manifold & Inlet Heater Treaters	5.28×101	5.28×101	1.2×101	1.2×101	1.2×101	
Corrosion Inhibitor Injection Skids	Oil Export Header & PW Injection Header	2.64×101	2.64×101	1.2×101	1.2×101	1.2×101	
Closed Drain Drum Pump	Main Plant Drain Drum	1.74×101	1.74×101	6.6×101	1.74×101	1.74×101	
Flares KOD Pumps	LP Flares Stack	8.4×101	8.4×101	1.44×101	8.4×101	3.36×101	
Flare Air Blowers	LP Flares Stack	26.4×101	26.4×101	17.76×101	17.76×101	17.76×101	
Instrument Air Compressor Package	Supply of Instrument Air to Plant	72.0×101	72.0×101	18.0×101	18.0×101	18.0×101	
Utility Water Unloading Pump	Supply of Utility Water to Utility Water Tank	71.52×102	71.52×102	2.64×102	7.152×101	7.152×101	
Utility Water Pump	Supply of Utility Water to Plant	13.776×101	13.776×101	14.4×102	13.776×101	13.776×101	
Diesel Unloading Pump	Supply of Diesel to Diesel Storge Tank	–	–	26.4×101	–	–	
Diesel Transfer Pump	Supply of Diesel to Plant	–	–	17.76×102	–	–	
Diesel Generators (350 kVA)	At each Producer Well	53.76×104	9.408×104	26.88×104	18.816×104	80.64×103	
Diesel Generators (1250 kVA)	Inside the Plant	10.56×105	26.88 ×103	46.08×103	33.6×103	20.160×103	
[45].

Mass Flow	Plant-1	Plant- 2	Plant- 3	Plant- 4	Plant −5	Unit	
Gross Fluid	36,088.77	17,370.26	22,570.46	15,050.78	10,714.67	bpd	
5737.48	2761.57	3588.31	2392.81	1703.45	m3/d	
5,381,759.05	2,590,350.53	3,365,833.60	2,244,455.78	1,584,204.29	kg/d	
Chemical - Deformer	–	62	6	29	28	l/d	
–	51.67	5	24.168	23.335	kg/d	
Chemical – Demulsifier	152.2	114	55	120	125	l/d	
126.562	94.552	55	120	125	kg/d	
Chemical – Corrosion Inhibitor	82.7	46	93.5	20	14	l/d	
66.14	36.8	74.8	16	11.2	kg/d	
Chemical – Oxygen Scavenger	–	18	–	–	–	l/d	
–	20.7	–	–	–	kg/d	
Chemical-H2S Scavenger	–	–	123.4	–	30	l/d	
–	–	138.875	–	32.439	kg/d	
Chemical – Scale Inhibitor	–	3	–	–	156	l/d	
–	3.9	–	–	202.8	kg/d	
Crude Oil (Product)	12,849.67	7981.15	5088.90	5332.86	3600.43	bopd	
2042.87	1268.86	809.047	847.832	572.406	m3/d	
Produced Water (by product)	23,026.26	7270.37	16,846.48	8634.92	6902.95	bwpd	
3660.77	1155.86	2678.30	1372.80	1097.45	m3/d	
3,660,773	1,155,862	2,678,296	1,372,801	1,097,448	kg/d	
Produced Gas (Total)	36,077.98	350,439.49	105,041.44	183,582.38	34,947.89	Sm3/d	
32,830,959.07	318,899,938.60	95,587,711.31	167,059,965	31,802,581.72	TOE (1 Sm3 x 910 = TOE)	
Waste Gas (Flared)	34,495.86	336,963.22	104,702.42	178,214.47	26,472.25	Sm3/d	
31,391,230.86	306,636,533.80	95,279,197.65	162,175,170	24,089,748.41	TOE (1 Sm3 x 910 = TOE)	
Waste Gas (Vented)	–	8249.62	–	5367.91	4237.82	Sm3/d	
–	7,507,157.84	–	4,884,794	3,856,416.20	TOE (1 Sm3 x 910 = TOE)	
Diesel	40,181.25	7200	18,850	13,200	6000	l/d	
33,752.25	6048	15,834	11,088	5040	kg/d	
[46].
==== Refs
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