Hydrogen is at present an important raw material for the synthesis of chemical compounds and for the processing of mineral oil, as well as an essential fuel for space transportation. Starting from present knowledge gained by working with hydrogen, the authors describe research and development needs and suggest some hydrogen energy applications which have early market possibilities. Since technical developments seem to be proceeding well, the main thrust of the paper is concerned with the efficient use of hydrogen as an energy carrier, as well as with the political and economic considerations associated with its introduction to the marketplace. Using the example of solar energy conversion technologies, the paper discusses the most important cost factors associated with the production of solar hydrogen as well as the dynamics of cost developments in the related technologies. It seems appropriate to conclude that with further research and development and with more efficient production techniques and large-scale operation significant cost reductions can be expected. But as long as current energy policies and the energy economy support the practice of not "internalizing" the costs of environmental damage, (and the further costs which ensue from this damage), the opportunity to build up an ecologically defensible energy economy will continue to be missed. The paper gives examples of external costs for energy conversion and relates them to internal costs. Noting that technical problems are increasingly being solved faster than are the non-technical ones, the paper concludes with a plea to continue research on and development of a unified "solar energy and solar hydrogen" system, one which includes all the relevant technical, economic, ecological, and political factors. © 1990.
