In recent years there has been a marked increase in the level of public concern with environmental issues. One of its effects has been a growing awareness of contribution that might be made by greater exploitation of renewable energy sources - frequently described as alternative energy sources, or 'the renewables'. Conventional large-scale power generation has been widely thought objectionable because it is polluting, causes damage to life and to valued buildings, emits radiation or generates more heavy goods traffic. Whether or not all these objections are valid there is no doubt that many of the renewables are comparatively free of them. Renewable Energy Sources is a Watt Committee report presenting and analysing the sources of renewable energy, including advantages and disadvantages, projects implemented internationally, cost and environmental implications, and the benefits of system integration.