Siemens researchers are using a flat structure in fuel cells to give them less resistance and greater efficiency while significantly reducing their manufacturing cost.
By building the tubes normally used in fuel cells as flat sheets, the researchers claim they have reduced resistance, so the generated current has a shorter distance to travel.
Material is currently the greatest cost factor in the manufacturing of fuel cells. By using the flat design, Siemens said it achieved three times the power density with the same amount of material.
Current fuel cells have long tubes inside them, surrounded by natural gas, into which air is pumped. When hydrogen and oxygen react to form water, the tubes generate a small voltage but high currents. To improve the energy production of the cells and achieve higher voltage levels, the tubes are connected using conductive struts. But this will generate electric resistance and cause power loss.
The Siemens researchers have "significantly" reduced the resistance in the tubes by putting 10 tubes next to one another in the flattened cell. This reduces the distance the current has to travel.
Siemens' research is focusing on solid-oxide fuel cells that can be operated directly with natural gas at temperatures of around 1,000C. When used in conjunction with a micro gas turbine that uses the hot exhaust gases, Siemens claims that the cells can achieve electrical efficiency levels of 55 percent.
Using the waste heat from the cell for heating purposes increases the efficiency further. The company predicts that by using all of these techniques, the overall efficiency of the fuel cell could be greater than 80 percent.