of a solar energy recovery device. While an expected future installed module cost of about $1/Wp is very attractive for electricity generation and deserves a strong research effort in its own right, this cost fails to provide hydrogen at a competitive value. It is apparent that there is no one method of harnessing solar energy that is a clear winner. However, it appears possible that new concepts may emerge that would be competitive.

In the future, if the cost of the fuel cell system approaches $50/kW, the cost of the electrolyzer is also expected to approach a low number (about $125/kW). Such low capital costs for electrolyzer units, together with levelized electricity costs in the neighborhood of $0.02 to $0.03/kWh, would result in a competitive hydrogen cost. It is also estimated that for a photoelectrochemical method to compete, its cost needs to approach $0.04 to $0.05/kWh. The order-of-magnitude reductions in cost for both hydrogen processes are similar.

Recommendations

Recommendation 8-14. Because of the large volume of hydrogen potentially available from solar energy and its carbon dioxide-free hydrogen, multiple paths of development should be pursued until a clear winning technology emerges for hydrogen production. There is a need for more basic research to provide a low-cost option. More specifically, alternate new technologies for harnessing solar energy should be developed, as well as new and novel methods to substantially reduce the manufacturing cost of some of the promising known technologies.

Recommendation 8-15. While basic research in photoelectrochemical as well as other methods that directly convert solar energy to hydrogen should be actively pursued, the route of solar electricity generation coupled with use of an electrolyzer for hydrogen production should also be pursued in a balanced Department of Energy solar program. A more aggressive target for photovoltaic solar of about $0.02 per kilowatt-hour (roughly $200 to $300 per kilowatt for the solar module) requires research on new and novel approaches. This will be especially important if improvements in battery storage density and cost are not achieved and hydrogen usage becomes dominant.



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