Cooking and providing light are primary, fundamental energy uses. As we've discussed before, half the world still uses biofuels like wood and dung to do their cooking. Building better cookstoves and light sources is pretty high on the planetary to-do list.

Anil K. Rajvanshi has a great overview of some of the recent research in the field, including new developments in biogas, more efficient mantles for lanterns, LEDs human-powered electrical systems, new products like Freeplay's wind-up radios and flashlights and new technologies:

Recent developments in nanotechnology and new materials have also shown that efficient devices that also convert heat directly into energy can be developed. For instance, coin-sized 'nano-engines' that can produce ten watts of energy from biomass fuels such as ethanol, are already being developed by researchers at the US-based Massachusetts Institute of Technology and University of California, Berkeley for defence purposes and to power mobile phones. The devices could also power LED lamps, revolutionising rural lighting. Such a compact system would bypass the need for bulky and costly batteries, since the liquid fuel itself would store the energy. This could result in an extremely compact and lightweight decentralised lighting source.