Green Energy

Green energy is the term used to describe sources of energy that are considered to be environmentally friendly and non-polluting, such as geothermal, wind, solar, and hydro. Sometimes nuclear power is also considered a green energy source. Green energy sources are often considered "green" because they are perceived to lower carbon emissions and create less pollution.

Green energy is commonly thought of in the context of electricity, mechanical power, heating and cogeneration. Consumers, businesses, and organizations may purchase green energy in order to support further development, help reduce the environmental impacts of conventional electricity generation, and increase their nation’s energy independence. Renewable energy certificates (Green certificates or green tags) have been one way for consumers and businesses to support green energy.

Pollution

Pollution is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms .[1] Pollution can take the form of chemical substances, or energy, such as noise, heat, or light energy. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Pollution is often classed as point source or nonpoint source pollution. The Blacksmith Institute issues annually a list of the world's worst polluted places. In the 2007 issues the ten top nominees are located in Azerbaijan, China, India, Peru, Russia, Ukraine and Zambia.

Wind power

Wind power is the conversion of wind energy into a useful form, such as electricity, using wind turbines. At the end of 2008, worldwide nameplate capacity of wind-powered generators was 121.2 gigawatts. Wind power produces about 1.5% of worldwide electricity use, and is growing rapidly, having doubled in the three years between 2005 and 2008. Several countries have achieved relatively high levels of wind power penetration, such as 19% of electricity production in Denmark, 11% in Spain and Portugal, and 7% in Germany and the Republic of Ireland in 2008. As of May 2009, eighty countries around the world are using wind power on a commercial basis.

Large scale wind farms are typically connected to the local electric power transmission network, with smaller turbines being used to provide electricity to isolated locations. Utility companies increasingly buy back surplus electricity produced by small domestic turbines. Wind (and solar) energy as a power source is favoured by environmentalists as an alternative to fossil fuels, as they are plentiful, renewable, widely distributed, clean, and produces no greenhouse gas emissions; although the construction of wind farms is not universally welcomed due to their visual impact and other effects on the environment.

Wind power, along with solar power, is non-dispatchable, meaning that for economic operation all of the available output must be taken when it is available, and other resources, such as hydropower, must be used to match supply with demand. The intermittency of wind seldom creates problems when using wind power to supply a low proportion of total demand. Where wind is to be used for a moderate fraction of demand, additional costs for compensation of intermittency are considered to be modest.

Solar energy

Solar energy is the radiant light and heat from the Sun that has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomass account for most of the available renewable energy on Earth. Only a minuscule fraction of the available solar energy is used.

Solar power provides electrical generation by means of heat engines or photovoltaics. Once converted its uses are only limited by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, hot water, thermal energy for cooking, and high temperature process heat for industrial purposes.

Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute sunlight. Active solar techniques include the use of photovoltaic panels, solar thermal collectors, with electrical or mechanical equipment, to convert sunlight into useful outputs. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.