NETL’s work with solid oxide fuel cells is enhancing the nation’s electric grid by generating combustion-free power with minimal environmental impact. The Lab is now extending its research vision to develop reversible solid oxide cells, which can alternately either generate power or produce clean-burning fuel.

Solid oxide cells operate in two modes: fuel cell mode and electrolysis mode. Solid oxide cells operating in fuel cell mode are known as solid oxide fuel cells, or SOFCs, while solid oxide cells operating in electrolysis mode are known as solid oxide electrolysis cells, or SOECs.

SOFCs convert chemical energy from a fuel directly into electrical energy. A fuel source such as hydrogen, natural gas or syngas is fed into the cell, and electricity, water and/or CO₂ are produced as byproducts. Since SOFCs produce electricity through an electrochemical reaction and not through a combustion process, they are much more environmentally friendly than conventional electric power generation methods due to higher efficiencies, reduced water usage and reduced CO₂ emissions.

SOECs function as an SOFC running backwards. This technology has been the focus of NETL’s recent research. Instead of generating electricity and producing water and/or CO₂, these components are fed into the SOEC to produce hydrogen, oxygen and/or carbon monoxide. These valuable chemicals can be used in a range of clean energy applications, from creating crucial value-added chemicals to serving as fuel sources in other alternative energy production methods.

Solid oxide cells operating in reversible mode (known as reversible solid oxide cells, or R-SOCs) can both store energy and produce electricity in a single solid oxide cell system and contributes to the creation of a clean energy generation/storage system when paired with renewable energy sources. Hydrogen created from SOECs is a promising clean-burning fuel source and can be stored for future use when renewable energy sources aren’t available. When the grid demands power, reversible solid oxide cells operate in SOFC mode and consume the stored hydrogen to produce electricity. This allows for the continuous implementation of clean energy into the grid.  

To enhance this game-changing technology for widespread implementation, NETL researchers are specifically studying the impact of reversible operation on long-term cell degradation. R-SOCs operating as SOECs are subject to degradation due to high pressure buildup and highly corrosive conditions. Because of this, finding an economical solution to this problem is paramount to future commercialization. The Lab is addressing this challenge by exercising its expertise in computer modeling to aid in designing new solid oxide cells that have higher performance capabilities and longer lifetimes. These efforts will make the energy conversion process easier and more efficient, which saves taxpayer dollars while reducing fossil fuel dependence.

NETL researchers are also currently testing an engineering technique that has already shown promising results in enhancing the performance and stability of solid oxide cells operating in fuel cell mode. The patented electrode engineering process, referred to as spray infiltration, introduces new materials into the cell components to boost cell activity and reduce targeted degradation modes. Research is being conducted to achieve the same benefits in reversible solid oxide cells and further elevate their potential to enhance the grid.

By improving upon current reversible solid oxide cell technology, NETL demonstrates its commitment to providing environmentally responsible solutions for today and options for tomorrow.