World Bank Technical Paper 240. Uses the findings of more than 50 studies on the historic and projected costs of renewable energy technologies to develop a common basis for comparing the costs of photovoltaics, solar-thermal, and biomass technologies. This review estimates the costs and assesses the implications of generating liquid fuels and electricity through the use of renewable energy technologies. The author finds that improvements in technology and a shift toward cheaper crops are behind reductions in the cost of ethanol production since the 1970s and concludes that further cost decreases can be expected. Costs of electricity from biomass generation compare favorably with those of fossil-fuel generation and even hydro generation. While the experimental state of solar-thermal technologies can cause great variability in costs, the author concludes that these technologies hold the potential for low-cost storage, high efficiency, and short lead times. He documents the very rapid decline in the cost of photovoltaic modules over the past twenty years and projects that costs will continue to be reduced as the technology is improved and commercialized. Ten annexes and over forty tables and figures examine the costs, efficiency, and parameters of the various technologies.