Carbon capture at natural gas power plants
‘Advancing economic and sustainable technologies to capture carbon dioxide from large emitters such as power plants is an important part of ExxonMobil’s suite of research into lower-emissions solutions to mitigate the risk of climate change,’ says Vijay Swarup, Vice President for R&D at ExxonMobil Research & Engineering Company.
‘Our scientists saw the potential for this exciting technology for use at natural gas power plants, to enhance the viability of carbon capture and sequestration while at the same time generating additional electricity,’ continues Swarup. ‘We sought the industry leaders in carbonate fuel cell technology to test its application in pilot stages, to help confirm what our researchers saw in the lab over the last two years.’
Fuel cells to capture carbon
‘Carbon capture with carbonate fuel cells is a potential game-changer for affordably and efficiently concentrating carbon dioxide for large-scale gas and coal-fired power plants,’ says Chip Bottone, president and CEO of FuelCell Energy.
‘Ultra-clean and efficient power generation is a key attribute of fuel cells, and the carbon capture configuration has the added benefit of eliminating approximately 70% of the smog-producing nitrogen oxide (NOx) generated by the combustion process of these large-scale power plants,’ he explains.
Carbon capture with power generation
When natural gas is burned in a gas turbine, the exhaust produced is only about 4% carbon dioxide. Molten carbonate fuel cells can collect that CO2, concentrate it into a stream that is around 70–80% CO2, while creating more electricity at the same time.
Further processing increases the CO2 concentration to over 95%. While this is a promising start, ExxonMobil and FuelCell Energy are planning to test and improve the technology to further increase its efficiency and demonstrate it at larger scale. The goal is to minimise emissions while maximising power output.
Lab tests show highly efficient carbon capture
Two years of comprehensive laboratory tests have demonstrated that the unique integration of two existing technologies – molten carbonate fuel cells and natural gas-fired power generation – captures CO2 more efficiently than existing scrubber conventional capture technology.
The potential breakthrough comes from an increase in electrical output using the fuel cells, which generate power, compared to a nearly equivalent decrease in electricity using conventional technology.
The resulting net benefit has the potential to substantially reduce costs associated with carbon capture for natural gas-fired power generation, compared to the expected costs associated with conventional separation technology. A key component of the research will be to validate initial projected savings of up to one-third.
Two-phase focus for pilot demonstration
The scope of the agreement between ExxonMobil and FuelCell Energy will initially focus for one to two years on how to further increase efficiency in separating and concentrating CO2 from the exhaust of natural gas-fueled power turbines.
Depending on reaching several milestones, the second phase will more comprehensively test the technology for another one to two years in a small-scale pilot project, prior to integration at a larger-scale pilot facility.
Carbon capture technologies
Oil & gas giant ExxonMobil is a leader in carbon capture and sequestration, and has extensive experience in all of the component technologies of carbon capture and storage, including participation in several CO2 injection projects over the last three decades.
In 2015, ExxonMobil captured 6.9 million metric tonnes of CO2 for sequestration – the equivalent of eliminating the annual greenhouse gas emissions of more than 1 million passenger vehicles.
‘We are continually researching technologies that have an ability to reduce carbon dioxide emissions,’ says Vijay Swarup. ‘Most solutions that can make an impact of the scale that is required are not found overnight. Our research with FuelCell Energy will be conducted methodically to ensure that all paths toward viability are explored.’
Carbonate fuel cells concentrate CO2
Using molten carbonate fuel cells to capture CO2 from power plants results in reduced emissions and increased power generation. In the carbon capture context, power plant exhaust is directed to the fuel cell, replacing air that is normally used in combination with natural gas during the fuel cell power generation process.
As the fuel cell generates power, the CO2 becomes more concentrated, allowing it to be more easily and affordably captured from the cell’s exhaust, and stored.
FuelCell Energy power plants run on variety of fuels
FuelCell Energy is a global leader in providing ultra-clean baseload distributed generation to utilities, industrial operations, universities, municipal water treatment facilities, government installations, and other customers around the world.
The company’s Direct FuelCell® power plants have generated over 4 billion kWh of ultra-clean power using a variety of fuels, including renewable biogas from wastewater treatment and food processing, as well as clean natural gas.