Ever since the first oil crisis in 1973, there has been a great deal of experimentation with renewable energy sources. A considerable amount of government money has been spent on renewable energy R&D, although just a fraction of the amount allocated to nuclear R&D (OECD/IEA, 1997). A common reaction is, however, that very little has come out of that research in terms of commercially interesting energy technologies.1 This perception was entirely correct in the 1970s, remained broadly true in the 1980s but is now becoming increasingly incorrect.