Incluye bibliografía.

Foreword -- Abstract -- Acknowledgments -- Abbreviations and acronyms -- 1. Overview -- 2. Biomass energy -- 3. Solar-thermal -- 4. Photovoltaics -- Bibliography -- Annexes -- Tables -- Figures.

This paper examines the evidence on the historic and projected costs of selected renewable energy technologies and assesses developments. It reviews estimates of more than 50 studies and expresses the costs on a common basis for photovoltaics, solar-thermal, and biomass for liquid fuels and electricity production. Findings show that there has been a decline in the cost of ethanol production since the 1970 ' s, attributable to technology improvements and a shift toward cheaper crops. The technology developments to convert low-cost cellulosic materials to ethanol promise further reductions in cost. The costs of electricity from biomass show great variability. Costs are site-specific and vary with raw material costs but still compare well with the costs of fossil-fired generation and even hydro generation in favorable situations. Costs of electricity from solar-thermal technologies show much variability because--with the notable exception of the parabolic trough technology--all are in the experimental stage. However, experience to date and engineering analysis both point consistently to costs in the 5 to 10 cents per kilowatt hour range in the next generation of schemes. Furthermore, the possibilities for low-cost storage, high conversion efficiencies, and short lead times make this an attractive option. Costs of photovoltaic modules have decreased by a factor of 10 over the past fifteen years and by more than 50 since the early 1970s. The possibilities for further cost reduction are far from being exhausted. Key developments with concentrator cells and multijunction devices, commercialization of new thin-film devices, and introduction of batch production processes in manufacturing promise further reductions.