The Future of Carbon Capture and Storage with Carbonate Fuel Cells

ExxonMobil affiliate Esso Nederland B.V. (Rotterdam, the Netherlands; www.esso.nl) is planning to build a pilot plant at its Rotterdam manufacturing complex to generate performance and operability data for a modular carbon-capture and storage (CCS) technology based on carbonate fuel cells.

The pilot plant, which is expected to be operational by late 2024, will test the feasibility of using carbonate fuel cells to capture CO2 from flue gas streams of natural gas-fired power plants and industrial facilities. The project is part of a joint development agreement between ExxonMobil and FuelCell Energy, Inc. (Danbury, Conn.; www.fuelcellenergy.com), a leading developer of carbonate fuel cell technology.

What are carbonate fuel cells and how do they work?

Carbonate fuel cells are a type of high-temperature fuel cells that use a molten mixture of salts, such as lithium, sodium, and potassium carbonate, as the electrolyte. The electrolyte conducts carbonate ions (CO32-) from the cathode to the anode, where they react with hydrogen and carbon monoxide from the fuel to produce water, carbon dioxide, and electricity. The fuel can be derived from natural gas, biogas, coal, or other sources. The carbon dioxide produced at the anode can be separated and compressed for transportation and storage, while the excess heat and electricity can be used for power generation or other purposes.

The advantages of carbonate fuel cells include high efficiency, low emissions, fuel flexibility, and scalability. Carbonate fuel cells can achieve efficiencies of up to 60%, compared to 37–42% for conventional power plants. They also have lower emissions of nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter, as well as lower water consumption. Carbonate fuel cells can use a variety of fuels, including natural gas, biogas, coal gas, and hydrogen, without the need for external reforming. They can also be configured in modular units that can be easily installed and expanded.

How can carbonate fuel cells be used for carbon capture?

Carbonate fuel cells can be used for carbon capture in two ways: direct fuel cell carbon capture and exhaust gas carbon capture.

  • Direct fuel cell carbon capture: In this method, the fuel cell itself acts as a carbon capture device, as it produces a concentrated stream of CO2 at the anode that can be easily separated and stored. This method can be applied to any fuel cell system that uses carbon-containing fuels, such as natural gas, biogas, or coal gas. The advantage of this method is that it does not require any additional equipment or energy for carbon capture, and it can also increase the power output and efficiency of the fuel cell system by reducing the parasitic load of CO2 removal.
  • Exhaust gas carbon capture: In this method, the fuel cell is used to capture CO2 from the exhaust gas of another power plant or industrial facility. The exhaust gas, which contains about 8–15% CO2 by volume, is fed to the cathode of the fuel cell, where it reacts with oxygen and carbonate ions to produce water and CO2. The CO2 is then transferred to the anode, where it can be separated and stored. The advantage of this method is that it can be retrofitted to existing power plants and industrial facilities, and it can also generate additional electricity from the fuel cell.
Method Fuel cell system Carbon capture device CO2 concentration Power output Efficiency
Direct fuel cell carbon capture Any fuel cell system that uses carbon-containing fuels Fuel cell anode High (90–100%) Increased Increased
Exhaust gas carbon capture Fuel cell system that uses hydrogen or other non-carbon fuels Fuel cell cathode High (90–100%) Additional Slightly decreased

What are the benefits and challenges of carbonate fuel cell carbon capture?

Carbonate fuel cell carbon capture has several benefits over conventional carbon capture methods, such as amine scrubbing or membrane separation. These benefits include:

  • Higher efficiency: Carbonate fuel cell carbon capture can reduce the energy penalty of carbon capture by generating electricity from the fuel cell, while conventional methods consume energy for CO2 separation and compression. According to a study by the US Department of Energy, carbonate fuel cell carbon capture can increase the net efficiency of a natural gas power plant from 49.9% to 55.3%, while amine scrubbing can decrease it to 40.4%
  • Lower cost: Carbonate fuel cell carbon capture can reduce the cost of carbon capture by avoiding the need for expensive solvents, membranes, or other materials, as well as reducing the size and complexity of the carbon capture equipment. According to a study by ExxonMobil and FuelCell Energy, carbonate fuel cell carbon capture can reduce the cost of carbon capture by up to 67%, compared to amine scrubbing
  • Lower emissions: Carbonate fuel cell carbon capture can reduce the emissions of other pollutants, such as NOx, SOx, and particulate matter, by using a cleaner and more efficient fuel cell system, while conventional methods may increase the emissions of these pollutants due to the increased fuel consumption and flue gas recirculation. According to a study by the US Department of Energy, carbonate fuel cell carbon capture can reduce the NOx emissions of a natural gas power plant by 98%, compared to amine scrubbing

However, carbonate fuel cell carbon capture also faces some challenges that need to be overcome before it can be widely deployed. These challenges include:

  • Durability: Carbonate fuel cells operate at high temperatures (600–700 °C) and use corrosive electrolytes, which can accelerate the degradation and corrosion of the fuel cell components and materials, decreasing the cell life and performance. Scientists are currently exploring corrosion-resistant materials and fuel cell designs that can increase the durability and reliability of the fuel cell system
  • Scalability: Carbonate fuel cells need to be scaled up to match the large volumes of CO2 produced by power plants and industrial facilities, which can pose technical and economic challenges. Scientists are currently developing modular and flexible fuel cell systems that can be easily installed and integrated with existing facilities
  • Regulation: Carbonate fuel cell carbon capture needs to comply with the regulatory and legal frameworks for carbon capture and storage, which can vary by region and country. These frameworks need to address the issues of CO2 transportation, storage, monitoring, verification, and liability, as well as the incentives and policies for carbon capture and storage deployment

What are the current and future prospects of carbonate fuel cell carbon capture?

Carbonate fuel cell carbon capture is still in the early stages of development and demonstration, but it has shown promising results and potential for commercialization. Some of the current and future projects and initiatives involving carbonate fuel cell carbon capture are:

  • The pilot plant at Rotterdam: This project, which is a collaboration between ExxonMobil and FuelCell Energy, aims to build and operate a 10-MW pilot plant that will use carbonate fuel cells to capture CO2 from the flue gas of a natural gas-fired power plant at the Rotterdam manufacturing complex. The project will test the performance and operability of the fuel cell system, as well as the integration with the existing power plant and the CO2 transportation and storage infrastructure. The project is expected to be operational by late 2024 and will capture up to 100,000 metric tons of CO2 per year
  • The Southern Company project: This project, which is funded by the US Department of Energy, aims to demonstrate the feasibility and economics of using carbonate fuel cells to capture CO2 from the exhaust gas of a coal-fired power plant. The project will use a 2.7-MW fuel cell system provided by FuelCell Energy to capture up to 70% of the CO2 from a slipstream of the flue gas of a 770-MW power plant operated by Southern Company in Alabama. The project is expected to be completed by 2023 and will capture up to 10,000 metric tons of CO2 per year
  • The Carbon Capture Coalition: This is a coalition of more than 80 companies, organizations, and associations that support the development and deployment of carbon capture and storage technologies in the US. The coalition advocates for policies and incentives that can accelerate the commercialization and adoption of carbon capture and storage, including carbonate fuel cell carbon capture. The coalition also facilitates the collaboration and communication among the stakeholders and the public on the benefits and challenges of carbon capture and storage

Carbonate fuel cell carbon capture is an innovative and promising technology that can offer a viable solution for reducing CO2 emissions from power plants and industrial facilities, while also generating additional electricity and reducing other pollutants. The technology has the potential to play a significant role in the transition to a low-carbon economy and the mitigation of climate change. However, the technology also faces some technical, economic, and regulatory hurdles that need to be overcome before it can be widely deployed. Therefore, more research, development, demonstration, and collaboration are needed to advance and commercialize carbonate fuel cell carbon capture.


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