Renewable electricity-what is the true cost?

Energy consumed in the chain of processes from extraction, processing, fabrication/manufacture and transport to their ultimate end use is embodied in all materials. Depending on the particular fuels employed, the specific process used and the degree of materials recycling/reuse at each stage of the chain, a particular manufactured item will concomitantly embody environmental emissions and wider consequential environmental impacts. The renewable energy generation of electricity is advocated as a means of reducing carbon dioxide emissions associated with the generation from fossil fuels. Renewable sources, as with fossil-fuelled plants, embody significant emissions in their materials of construction. "Full-chain" embodied energy and CO/sub 2/ emissions calculations for wind, hydro, solar-thermal and photovoltaic conversion are quite different and the likely trend in future reduction of embodied energy of next generation systems reflects the relative maturity of each technology.