Introduction
Driven by consumer demands for cleaner energy systems, governments’ pledges towards decarbonization targets, and investor pressures for reliable environmental social and governance (ESG) performance, the need of transforming the industrial processes to be more energy-efficient and sustainable has become mandatory and urgent for industries themselves to continue operating in the market.
The Oil & Gas industry will be one of the most affected by this transition, which will demand a profound transformation of their business. Yet, it is a necessary challenge this sector must face, considering that Oil & Gas operations today are responsible for around 15% of all energy-related GHG emissions globally, a percentage equivalent to 5.1 billion tonnes of greenhouse gas emissions.
Oil & Gas operators and companies are taking action at three levels along their journey to decarbonization:
- Decarbonize their core business activities by minimising emissions and maximising efficiency from current operations, infrastructure, and value chains, using proven and fast-to-implement clean technologies and measures.
- Transition to new cleaner sources by replacing fossil fuel sources of energy and demand with available and competitive cleaner and zero-emission renewables.
- Be forerunner of a NetZero future by investing in new processes and technologies that are beyond what is commercially and technically possible today.
Simply concentrating actions at level 1, by reducing or eliminating the emissions associated with their current operations, can reduce an oil and gas company’s direct emissions by 80 percent, lowering them by almost 20 Gt. (Source: Accenture decarbonization scenario “Decarbonizing Energy: From A to Zero”)
Clean Technologies in Oil & Gas Industry
Among the clean technologies and the measures available to act at level 1 to cut carbon emission and optimise efficiency the International Energy Agency and Accenture mention in their reports:
● Minimising methane emissions and eliminating all non-emergency flaring.
● Electrifying upstream facilities and O&G processes with low-emissions electricity.
● Deploy circular solutions that reduce energy intensity and waste from operations.
● Equipping oil and gas processes with carbon-capture, utilisation, and storage technologies.
● Expanding the use of hydrogen from low-emissions electrolysis in refineries.
Minimising methane emissions and eliminating all non-emergency flaring
IEA estimates around 80 Mt of methane emissions, equivalent to 2.4 Gt CO2-eq., are caused every year by the O&G operations. These emissions can be lowered employing well-known and already adopted clean technologies and measures that prevent methane leakings. Examples of useful measures are:
● Replacing devices such as pumps, compressor seals, or rods.
● Installing new devices such as vapour recovery units, blowdown capture systems, and flare plungers.
● Conducting leak detection campaigns and carrying out repairs.
Electrifying upstream facilities and O&G processes with low-emissions electricity
Oil and gas upstream activities require a large quantity of energy to power all the equipment employed for gas extraction. The primary fuels used to produce this power in upstream operations are diesel and gas engines. IEA estimates that the energy demand for these upstream oil and gas processes produced more than 700 Mt CO2 in 2022. By electrifying all the upstream processes great energy efficiency gains could be achieved. Once again, IEA calculates that around 400 Mt CO2 would be technically avoidable through electrifying facilities.
Deploy circular solutions that reduce energy intensity and waste from operations
Several clean technologies are available in the market that can help make the O&G processes more energy efficient thus reducing their energy demand. Among these, one of the most efficient, flexible, and ready to deploy is the Rankine Cycle, in particular the Organic Rankine Cycle (ORC) technology. ORCs are a perfect fit for circular reuse of waste byproducts from O&G operations, specifically waste heat energy. They are employed to produce clean, zero emission energy exploiting waste heat potential, thus reducing the energy intensity and the emissions of the processes. A dated Waste Heat to Power Market Assessment prepared for the U.S. Department of Energy (DOE) in 2015 estimated that around 9000 MW of clean electricity could be generated by recovering the Waste Heat technical potential at 2,946 sites. Over 40% of the potential total capacity (3,593 MW) was estimated to be in the petroleum refining sector. Natural gas pipeline transmission accounted for over 1,300 sites representing over 12% of the technical potential in terms of capacity (1,102 MW).
Equipping oil and gas processes with carbon-capture, utilisation, and storage (CCUS) technologies
CCUS technologies are among the decarbonization technologies mostly utilised by the O&G industry. There are today 15 large CCUS projects in operation that capture and store 25 Mt CO2 per year from natural gas processing. Increasing the deployment of CCUS technologies to reduce CO2 emission can avoid the emission of 160 Mt CO2 by 2030, according to IEA NetZero scenario
Expanding the use of hydrogen from low-emissions electrolysis in refineries.
Based on the IEA report, Electrolysis hydrogen will play a smaller role in reducing oil and gas emissions before 2030, but will be key for much larger reductions by 2050. In the IEA Net Zero Scenario, around 6 Mt of low-emissions electrolysis hydrogen is projected to be used in refineries in 2030. Around 65% of this is produced on site at refineries themselves, and the remainder is purchased from external suppliers.
Exergy’s ORC Technology for Sustainable Energy Solutions
Exergy’s ORC systems, which employ the highly efficient Radial Outflow Turbine, can provide a great solution to the O&G industry’s need to reduce energy intensity and waste from operations.
Exergy’s ORC products are used for clean power production from renewables, including geothermal, biomass, and solar, as well as for waste heat recovery from several industrial processes, including Oil & Gas. Exergy’s solutions range from small power size modular units up to tailored power plants with turbines of 20 MWe each. They can be applied to exploit low to medium-temperature waste heat sources ranging from 90 up to 400° C.
Exergy: Clean Energy Solutions and Sustainable Innovations for the Oil & Gas Industry
In the O&G industry Exergy’s ORC systems can be effectively employed in midstream processes such as:
● Gas compression;
● Pressure let-down stations in pipeline transportation systems;
● LNG regasification plant;
● Refining and petrochemical processes.
The potential of exhaust-heat recovery from O&G processes is sizable, only considering that gas turbines reject roughly 50% of the energy in the fuel into the atmosphere through their exhaust systems.
Waste heat recovery (or Waste Heat to Power) from Gas Compression
Gas turbines driving compressors in use in pipelines could benefit from the implementation of waste heat recovery systems to achieve optimal emission and consumption levels. An ORC system can be applied to multiple gas turbines within a station. In this way, one single ORC power plant can increase the power output available in a gas compressor station by up to 40% and, therefore, reduce the use of fossil fuels to drive the compression. This, in turn, helps avoid the CO2 emissions associated with fossil fuel generated electricity.
Clean energy production in pressure let-down gas stations
In pressure let-down stations, natural gas pressure is decreased to reach the suitable distribution network pressure. During this process, potential energy, in the form of high-pressure difference, is completely lost in the lamination process through a valve. This wasted energy can be efficiently recovered by Exergy’s Gas Expander to generate zero-emission electricity.. Exergy has designed a natural gas expander system that integrates into existing pressure-let down gas stations, benefitting both industries and residential buildings. This system increases the efficiency and sustainability of gas distribution systems, producing clean, carbon-free electricity from exhaust heat.
Waste heat recovery (or Waste Heat to Power) in LNG regasification plants
In LNG regasification terminals, the simpler application of ORC technology is to recover the exhaust waste heat downstream gas turbines utilised in the LNG process An example of this application can be found is Exergy’ reference in Thailand, Rayong, in the LNG regasification plant of PPT LNG. For this project, Exergy designed and supplied an ORC unit equipped with a Radial Outflow Turbine that recovers the exhaust heat generated downstream from the two Solar Mars 100 gas turbines installed in the LNG plant. This systemconverts that heat into 5 MWe of clean electricity.
Recently, the Exergy R&D department has developed a new clean technology based on ORC to be applied in the LNG regasification process. This clean technology is the Cold Energy Plant (CEP). The Cold Energy Plant designed by Exergy can be employed to regasify liquified natural gas and convert the heat absorbed from sea water into electricity by recovering the valuable exergy content of LNG. This solution allows to produce clean electrical power on-site without any additional external fuel consumption and no emissions at stacks. The CEP is a low-maintenance and cost-effective solution that can be efficiently applied in the LNG industry to increase energy efficiency and sustainability of operations.
Waste heat recovery from refining and petrochemical processes
In Refining and petrochemical processes, the heat typically dissipated in cooling units, such as air cooled condensers, which consume energy, could be recovered by means of an ORC. This clean technology can be applied to all chemical and petrochemical plants and can be used in new plants or as retrofits for existing ones. By installing an ORC in refining and petrochemical processes, it is possible to convert up to 30% of the recovered waste heat into clean electricity.
Benefits of Exergy’s Clean Technologies for Oil & Gas Industry
The benefits of installing an ORC clean energy system in Oil & Gas processes can be manifold.
In gas compression stations the deployment of such power plant can:
● Recover waste heat from multiple units operating in parallel, thus optimising the efficiency.
● Generate additional power up to 40% with any extra fuel consumption.
● Reduce conventional energy consumption and make the gas compression process more efficient.
● Reduce conventional energy costs.
● Increase profitability of operations.
● Reduce carbon footprint of the process
In pressure let-down stations ORC power plants allow to:
● Increase the efficiency of the operation up to 80%.
● Increase the profitability of the operation thanks to additional power production.
● Increase the sustainability of the operation.
For LNG regasification and petrochemical processes Exergy’s solution can be an effective measure to:
● increase the energy efficiency of the process.
● increase operational profitability.
● increase the sustainability of the LNG regasification process by reducing energy consumption and associated carbon emissions.
Conclusions
Investors, consumers, regulators and new startup cleantech companies are requiring all industrial sectors to transform their way of leading businesses, and meet the challenge of achieving a decarbonized energy future by 2050. Oil & Gas companies are requested to answer this challenge and seize the opportunity to lead the energy transition. The path will require the industry to work in different directions by reducing operational emissions to a minimum, collaborating with customers to compensate emissions, extending their capabilities and assets into new clean energy solutions.
While transitioning to a decarbonized energy future, already mature and market-ready clean technologies will be key as short-term measures to answer the immediate need of reducing energy demand and carbon emissions. In this scenario, Organic Rankine cycle technology reveals an effective, viable, and competitive cleantech solution for the Oil & Gas industry.
Exergy as a leading player in the ORC sector, with high expertise and customer oriented approach among its main strengths, can be a good partner to support O&G companies in their effort to reduce the impact of their operation on the environment.
