As prices at the pump hit an all-time high, UMR researchers are trying to help shrink our nation's dependence on fossil fuels and reduce pollution by improving fuel cells – the battery of the future. An expert in ceramics, Richard Brow, chair of materials science and engineering and professor of ceramic engineering at UMR, is part of a team developing a stronger solid oxide fuel cell sealant from glass-ceramic materials.
How do solid oxide fuel cells work?
A solid oxide fuel cell (SOFC) converts chemical energy to electrical energy directly without combustion, yielding much greater conversion efficiencies than steam turbines or internal combustion engines. Unlike batteries, which eventually become depleted, fuel cells can provide a continuous supply of electric power.
SOFCs operate at temperatures between 600 and 1000ºC, depending on designs and materials. SOFCs have four main components:
--a ceramic electrolyte
--electrically conducting ceramic cathodes
--metal-ceramic anodes
--stainless steel interconnect materials (for the low-cost, low-temperature designs).
Each of these materials require specific electrical, thermal, and chemical properties and are being developed by several research groups at UMR, including the team headed by Harlan Anderson, Curators’ Professor emeritus of ceramic engineering.
What steps need to be taken to get these types of fuel cells ready for use in vehicles?
A number of problems must be overcome before SOFCs will be ready for automotive applications. The most significant issue is cost. SOFC power generation is expensive compared with an internal combustion engine. If we can reduce the operational temperature from 900ºC to 700ºC, designers can use less-expensive materials and that will enhance the cell reliability.
Another problem involves the need to thermally cycle a fuel cell, from ambient temperatures to operating temperatures, thousands of times over the lifetime of an automotive system. This places stringent demands on the materials that are used. Thermal expansion mismatches between cell materials can lead to thermal stresses that can cause the cell to fail mechanically during a thermal cycle. In addition, the long-term stability of different materials in the high temperature fuel cell environment is a current focus of research that needs to be performed before reliable automotive SOFCs hit the roads.
Are solid oxide fuel cells better than polymer membrane fuel cells?
Solid oxide fuel cells have several advantages over polymer membrane cells, including much greater energy conversion efficiencies (approaching 60 percent, compared with about 35-50 percent for the polymer membrane fuel cells). In addition, polymer membrane cells require pure hydrogen as the fuel and are intolerant to fuel contaminants, whereas more readily available hydrocarbon fuels can be used directly with SOFCs. Finally, the polymer membrane cells often require heavy, auxiliary cooling systems that are not needed with SOFC designs.
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