Renewable energy is useful energy that is collected from renewable resources which are naturally replenished on a human time scale including carbon neutral sources like sunlight and wind along with waterfalls and even tides waves and geothermal heat. These types of energy sources stand in contrast to fossil fuels which are being used far more quickly than they are being replenished. Although most renewable energy are sustainable energy some is not for example some biomass is unsustainable. While many renewable energy projects are large scale but renewable technologies are also suited to rural and remote areas and developing countries where energy is crucial in human development. Energy deployment is applied in conjunction with further electrification as most of the renewable energy technologies provide electricity renewable which has several benefits. Electricity can be converted to heat. It can be converted into mechanical energy with high efficiency and is clean at the point of consumption. In addition electrification with renewable energy is more efficient and therefore leads to significant reductions in primary energy requirements. Renewable energy resources and significant opportunities for energy efficiency exist over wide geographical areas in contrast to other energy sources which are concentrated in the limited number of countries. Rapid deployment of renewable energy and technological diversification of energy sources would result in significant energy security and economic benefits. It would also reduce environmental pollution such as air pollution caused by the burning of fossil fuels and improve public health by reducing premature mortalities due to pollution and save associated health costs that amount to several hundred billion dollars annually only in the United States. Multiple analyses of decarbonization strategies have found that quantified health benefits can significantly offset the costs of implementing these strategies. Renewable energy sources that derive their energy from the sun either directly or indirectly such as hydro and wind are expected to be capable of supplying humanity energy for almost another one billion years at which point the predicted increase in heat from the Sun is expected to make the surface of the Earth too hot for liquid water to exist. Climate change and global warming concerns coupled with the continuing fall in the costs of some renewable energy equipment such as wind turbines and solar panels are driving increased use of renewables. New government spending regulation and policies helped the industry weather the global financial crisis better than many other sectors. The ability of biomass and biofuels to contribute to a reduction in carbon dioxide emissions is limited because both biomass and biofuels emit large amounts of air pollution when burned. Furthermore biomass and biofuels consume large amounts of water. Other renewable sources such as wind and hydroelectricity have the advantage of being able to conserve water lower pollution and reduce carbon dioxide emissions. The installations used to produce wind or hydro power are an increasing threat to key conservation areas with facilities built in areas set aside for nature conservation and other environmentally sensitive areas. More than two thousand renewable energy facilities are built and more are under construction in areas of environmental importance. And threaten the habitats of plant and animal species across the globe. Renewable energy devices depend on non renewable resources such as mined metals and use vast amounts of land due to their small surface power density.