Fuel Cells Fuels cells have been around for many years, but have yet to be truly commercialized. There are many companies working on the development of fuel cells, mainly for use in electric vehicles. At present, the installed costs for fuel cells are much higher than for photovoltaics. Some current costs of fuel cells: • a small demo cell from ElectroChem for S75/W. • BCS Technology air breathing fuel cell, at S54/W, or $40/W in volume purchase. But there is no fundamental technical reason why they cannot be cheaper than photovoltaics, if they are mass produced. One of the main appeals of fuel cells is that they run on hydrogen. Hydrogen can be generated by electrolyzing water and electrolysis can be powered by photovoltaics. The “clean fuel cycle” scenario is to make hydrogen from solar electricity, ship it world-wide to power fuel cells and the only output of a fuel cell is water. This is a completely clean cycle of energy. This eliminates two of the big disadvantages of PV. 1) The PV can be located where ever there is space and sun. 2) The fuel cell can supply industrial amounts of power 24 hours per day. There are numerous demonstration fuel cell systems, from those used to power electric buses to some for utility scale application that can produce megawatts of power. To generate 1 kWh, a typical fuel cell uses 700 liters of hydrogen. A demonstrated solar powered electrolyzer can produce hydrogen at a rate of 1500 liters/hour. This means that a 15.5 kW PV system, which takes up little more than an average rooftop, could supply 6 houses with enough hydrogen to generate 20 kWh-per day with their fiiel cells, if there were 6 hours of sun per day. Obviously, the cost of PV phis fuel cell phis hydrogen distribution is not going to be cheaper than PV. But it may become the power system of choice because it will be able to meet a variety of needs, from an individual house or electric vehicle to a large factory. This type of power system will have significant development costs. The mam difficulty with it is in trying to erect a new infrastructure to support it. This is not so much a technical problem as an economic and political one. It is unclear whether development costs associated with this system would be less than those associated with space solar power. But the solar-hydrogen-fuel cell system can be implemented incrementally, and implementation is already underway on a small scale. Demos have already been done, fuel cells, electrolyzers and PV can be readily purchased. Perhaps the biggest difficulty is that low cost requires mass production and mass production requires relative fast implementation. Incremental, yes, slow, no. Putting together the infrastructure for a solar-hydrogen-fiiel cell system has often been raised as a showstopper to doing it. This complaint seems silly in light of the dirty and inefficient system of oil extraction and transport we already have. Oil has to be found (drilling), extracted (punping), refined and transported. Hydrogen is made from water and solar electricity. Water is easier to find than oil, solar irradiance is known and no refining is necessary. Building a hydrogen pipeline system would be similar to the existing natural gas system Transporting hydrogen by tankers would have nearly the same safety requirements as transporting natural gas. A “spill” of hydrogen, while it could be spectacular, would leave nothing but water behind. Unlike many fossil fuel
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