Biomass energy accounts for more than 10 percent of renewable energy use today, and it could quadruple if aggressively pursued. Half could come from agricultural wastes and forestry residues, farm animal wastes and landfills, and half from dedicated energy crops. Geothermal energy has important niche possibilities in certain countries, Sheffield says, especially as an energy source for heat pumps. Hydropower delivers about two percent of world energy and that could be doubled. Despite concerns about submerging land, effects on species and eventual silting, water-generated electricity is an important resource for the developing world.
Numerous options exist for capturing solar energy.
It is difficult to set a level for the potential of solar power since, in principle, it could provide all of our energy needs if developments lower the cost sufficiently, he says. Energy from the sun is an especially promising option in arid or warm climates, where many of the developing nations reside. Solar electricity for lighting, water pumping and refrigeration is already cost competitive in remote areas with no electricity grid. Costs are decreasing rapidly. Solar water heating is widely used in some countries.