Abstract
Some Microorganisms belonging to the cyanobakteria (bluegreen algae) are able to convert solar energy directly into hydrogen (H2). This H2-evolution is based on the watersplitting reaction of photosynthesis (biophotolysis). Practical applications of these systems have been hindered by low solar conversion efficiencies and problems in designing practical systems. New developments in biotechnology and more research on the basic biology of cyanobacterial H2-evolution may help to increase conversion efficiencies from about 1% today to 10% or more in the future. Considering these technological developments an economic evaluation of the future potential of biophotolysis is presented showing that quite small system improvements are sufficient to reach a competitive position with present and future photovoltic systems.