Employing devices that convert sunlight and its heat into usable forms of energy. Solar electricity is a direct electrical current generated in a silicon cell by impacting sunlight. It can be used and stored for many normal electrical applications. Solar heat energy can be used passively for simple warming or the energy can be concentrated by flat plate collectors which expose a large thin surface, containing a liquid, to the sun. The sun's heat can be intensified with lenses and mirrors and stored in salts and/or stones. At high temperatures it can generate steam for mechanical applications. When appropriately trapped it can cook food.
Renewable energy in the form of biomass constitutes the bulk of energy used in most Sub-Saharan African countries, accounting for about 73% of total energy. The region has substantial renewable energy resources, including solar, hydro and wind power potential. Suitable renewable energy technologies have been developed and are mature enough to be applied on the continent and in other renewable- energy-rich regions. These include micro-hydro plants, solar photovoltaics (for water pumping and (electricity generation), biogas digesters, biomass-gasification systems, and improved stoves.
In 1995, Italy opened the largest solar power station in the world. The plant is made up of two and a half million solar cells that will generate 5 million kWh of electricity a year, sufficient for 3,000 homes. In the USA, a company has announced plans to build a 100 MW solar power station, as part of a plan to develop a 1,000 MW Solar Enterprise Zone in the Nevada desert. The 100 MW power station would be the largest solar operation in the USA, producing enough for a city of 100,000 inhabitants. A solar energy site in the Mojave desert, California, covers more than 750 hectares generating 354 megawatts of electricity. This meets the electricity needs of 17,000 homes. The suns rays are also be directed and focused to heat up substances such as foods in various parts of the world.
The UK's first solar powered office block was opened in 1995. Apart from backing the project, Greenpeace has committed £30,000 towards the dissemination of the solar project to architects, planners and schools around Britain. The solar panels used are among the most advanced in the world, and will generate up to half the building's electricity needs, and save 1,000 tonnes of carbon dioxide (CO2) over the next two decades. In the same year, Greenpeace Germany launched its national solar campaign to convince major companies in Germany to use solar panels on their office buildings.
A solar energy site in the desert in California produces 354 megawatts of electricity (enough for 17,000 homes). The site uses curved mirrors to track the sun across the sky, focusing its light onto tubes containing a synthetic oil which is heated to almost 400 degrees Celsius to heat water to produce steam which generates electricity through a turbine.
Sanga Saby, a Swedish conference center, uses solar-based energy generation to heat its saunas and swimming pool, uses rapeseed oil to run its farm equipment, and overall gets its energy primarily through geo-thermal sources, using the temperature differentials in Lake Malaren to produce energy. IKEA is researching ways to have the south wall of every new IKEA store constructed with solar panels.