Since its inception in 1958, NASA has been harnessing the unique properties of hydrogen to conduct missions. NASA's hydrogen technologies enable electrical power, life support and transportation systems. The agency continues to research, develop and test hydrogen technologies for future human space exploration vehicles as well as advanced terrestrial aircraft. One of the innovative ways in which NASA is implementing hydrogen usage is in its power cells.
Astronauts have been using them for power aboard spacecraft since the 1960s. Soon, perhaps, they'll be just as common on Earth - powering cars, trucks, laptop computers and cell phones. By combining hydrogen fuel with oxygen, Fuel Cells can produce plenty of electric power while emitting only pure water as exhaust. They're so clean that astronauts actually drink the water produced by fuel cells on the space shuttle. While Fuel Cells promise to be the environmentally-friendly power source of the future, some types run too hot to be practical and you can't "just fill 'er up" with hydrogen at most corner petrol stations. And fuel cell-based cars and computers are still relatively expensive. These obstacles have relegated fuel cells to a small number of demo vehicles and some speciality uses, such as power aboard the space shuttle and back-up power for hospitals and airports.
Now NASA-sponsored research is helping to tackle some of these obstacles. By finding a way to build "solid oxide" fuel cells that operate at half the temperature of current designs - 500°C instead of a blistering 1,000°C - researchers at the Texas Center for Superconductivity and Advanced Materials (TcSAM) at the University of Houston hope to make this kind of fuel cell both cheaper to manufacture and easier to fuel.
"Our key advance was making the heart of the fuel cell (the sheet of electrolyte that controls the flow of electrically charged ions) - out of a thin film only one micron thick," says Alex Ignatiev, the director of the NASA-funded TcSAM." In contrast, today's off-the-shelf solid-oxide fuel cells have electrolyte layers 100 microns thick or more (a micron is one thousandth of a millimetre). "The thinness cuts down internal resistance to electric current, so we can get comparable power output at much lower operating temperatures." To make this ultra-thin layer, Ignatiev and his colleagues at TcSAM don't simply shave down a chunk of bulk material until it's thin enough. Instead, they grow the electrolyte atom by atom, depositing one layer of atoms at a time in a process called epitaxy. The thin films in TcSAM fuel cells are about 1,000 atoms thick. The same power at half the temperature creates a domino effect of cost savings. For one, cheaper materials can be used to build them, rather than the expensive heat-tolerant ceramics and high-strength steels demanded by 1,000-degree fuel cells. The automobiles that would use these fuel cells can also forgo exotic materials and elaborate heat-dissipation systems, lowering manufacturing costs. All of this tips the scales of economic feasibility in the right direction.
