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What is sustainability?
It's more than environmentalism. It's about living and working in ways that don't jeopardize the future of our social, economic and natural resources. In business, sustainability means managing human and natural capital with the same vigor we apply to the management of financial capital. It means widening the scope of our awareness so we can understand fully the 'true cost' of every choice we make."
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Sustainable energy sources are energy sources which are not expected to be depleted in a timeframe relevant to the human race, and which therefore contribute to the sustainability of all species.
Sustainable energy sources are most often regarded as including all renewable sources, such as solar power, wind power, wave power, geothermal power, tidal power and others.
Discounting the small risk of large-scale nuclear accidents, terrorism and other major disasters, nuclear power and nuclear fusion meet this definition of sustainability, but there is controversy over whether or not they should be regarded as sustainable for social and political reasons.
In an attempt to define sustainable energy, one will undoubtedly encounter the concept of renewable energy or renewables. Renewables,are "flows of energy that are regenerative or virtually inexhaustible." The most common renewables include solar energy, wind energy, hydropower and biomass.
This idea of abundant energy flows, though a component in defining sustainable energy, is not the key component. The key component is sustainability. A suitable definition for sustainable energy, then, "is energy which is replenishable within a human lifetime and which causes no long-term damages to the environment." As such, sustainable energy promotes sustainability. Sustainability, here, is twofold, as it constitutes self-sustenance and the ability to foster sustainable development.
Biofuel
Biofuel (also called agrofuel) can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass. This article, however, is principally about biofuel used as transportation fuel. Most transportation vehicles require high power density provided by internal combustion engines. These engines require clean burning fuels, which are generally in liquid form, and to a lesser extent, compressed gaseous phase. Liquids are more portable because they have high energy density, and they can be pumped, which makes handling easier. This is why most transportation fuels are liquids.
Biomass
Biomass refers to living and recently dead biological material that can be used as fuel or for industrial production. Most commonly, biomass refers to plant matter grown for use as biofuel, but it also includes plant or animal matter used for production of fibres, chemicals or heat. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic material which has been transformed by geological processes into substances such as coal or petroleum.
Geothermal
Geothermal power (from the Greek words geo, meaning earth, and therme, meaning heat) is energy generated by heat stored beneath the Earth's surface or the collection of absorbed heat in the atmosphere and oceans. Prince Piero Ginori Conti tested the first geothermal generator on 4 July 1904, at the Larderello dry steam field in Italy. The largest group of geothermal power plants in the world is located in The Geysers, a geothermal field in California. As of 2007, geothermal power supplies less than 1% of the world's energy.
Hydroelectricity
Hydroelectricity is electricity produced by hydropower. It is a renewable source of energy, produces no waste, and does not produce carbon dioxide (CO2) which contributes to greenhouse gases. Hydroelectricity now supplies about 715,000 MWe or 19% of world electricity (16% in 2003), accounting for over 63% of the total electricity from renewables in 2005.Although large hydroelectric installations generate most of the world's hydroelectricity, small hydro schemes are particularly popular in China, which has over 50% of world small hydro capacity.
Solar energy
Solar energy is energy directly from the Sun. This energy drives the climate and weather and supports virtually all life on Earth. Heat and light from the sun, along with solar-based resources such as wind and wave power, hydroelectricity and biomass, account for most of the available flow of renewable energy.
Solar energy technologies harness the sun's energy for practical ends. These technologies date from the time of the early Greeks, Native Americans and Chinese, who warmed their buildings by orienting them toward the sun. Modern solar technologies provide heating, lighting, electricity and even flight.
Solar power is used synonymously with solar energy or more specifically to refer to the conversion of sunlight into electricity. This can be done either through the photovoltaic effect or by heating a transfer fluid to produce steam to run a generator.
Tidal power
Tidal power, sometimes called tidal energy, is a form of hydropower that exploits the movement of water caused by tidal currents or the rise and fall in sea levels due to the tides.Although not yet widely used, tidal power has potential for future electricity generation and is more predictable than wind energy and solar power. In Europe, tide mills have been used for over a thousand years, mainly for grinding grains.
Wave power
Wave power refers to the energy of ocean surface waves and the capture of that energy to do useful work - including electricity generation, desalination, and the pumping of water (into reservoirs). Wave power is a form of renewable energy. Though often co-mingled, wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Wave power generation is not a widely employed technology, and no commercial wave farm has yet been established.
Wind power
Wind power is the conversion of wind energy into useful form, such as electricity, using wind turbines. In windmills, wind energy is directly used to crush grain or to pump water. At the end of 2006, worldwide capacity of wind-powered generators was 73.9 gigawatts.[1] Although wind currently produces just over 1% of world-wide electricity use, it accounts for approximately 19% of electricity production in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland (2007 data). Globally, wind power generation more than quadrupled between 2000 and 2006.
Wind power is produced in large scale wind farms connected to electrical grids, as well as in individual turbines for providing electricity to isolated locations.
Wind energy is plentiful, renewable, widely distributed, clean, and reduces greenhouse gas emissions when it displaces fossil-fuel-derived electricity. The intermittency of wind seldom creates insurmountable problems when using wind power to supply up to roughly 10% of total electrical demand (low to moderate penetration), but it presents challenges that are not yet fully solved when wind is to be used for a larger fraction of demand.
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