The life-cycle greenhouse-gas emissions of solar power are in the range of 22 to 46 gram (g) per kilowatt-hour (kWh) depending on if solar thermal or solar PV is being analyzed, respectively. With this potentially being decreased to 15 g/kWh in the future.[121] For comparison (of weighted averages), a combined cycle gas-fired power plant emits some 400–599 g/kWh,[122] an oil-fired power plant 893 g/kWh,[122] a coal-fired power plant 915–994 g/kWh[123] or with carbon capture and storage some 200 g/kWh, and a geothermal high-temp. power plant 91–122 g/kWh.[122] The life cycle emission intensity of hydro, wind and nuclear power are lower than solar's as of 2011 as published by the IPCC, and discussed in the article Life-cycle greenhouse-gas emissions of energy sources. Similar to all energy sources were their total life cycle emissions primarily lay in the construction and transportation phase, the switch to low carbon power in the manufacturing and transportation of solar devices would further reduce carbon emissions. BP Solar owns two factories built by Solarex (one in Maryland, the other in Virginia) in which all of the energy used to manufacture solar panels is produced by solar panels. A 1-kilowatt system eliminates the burning of approximately 170 pounds of coal, 300 pounds of carbon dioxide from being released into the atmosphere, and saves up to 105 gallons of water consumption monthly.[124]


Concentrator photovoltaics (CPV) systems employ sunlight concentrated onto photovoltaic surfaces for the purpose of electrical power production. Contrary to conventional photovoltaic systems, it uses lenses and curved mirrors to focus sunlight onto small, but highly efficient, multi-junction solar cells. Solar concentrators of all varieties may be used, and these are often mounted on a solar tracker in order to keep the focal point upon the cell as the sun moves across the sky.[147] Luminescent solar concentrators (when combined with a PV-solar cell) can also be regarded as a CPV system. Concentrated photovoltaics are useful as they can improve efficiency of PV-solar panels drastically.[148]
Since the 1970s, Brazil has had an ethanol fuel program which has allowed the country to become the world's second largest producer of ethanol (after the United States) and the world's largest exporter.[125] Brazil's ethanol fuel program uses modern equipment and cheap sugarcane as feedstock, and the residual cane-waste (bagasse) is used to produce heat and power.[126] There are no longer light vehicles in Brazil running on pure gasoline. By the end of 2008 there were 35,000 filling stations throughout Brazil with at least one ethanol pump.[127] Unfortunately, Operation Car Wash has seriously eroded public trust in oil companies and has implicated several high ranking Brazilian officials.
America is embracing renewables, slowly. In 2016, Massachusetts passed a law promoting a huge investment in wind and hydropower; the first megawatt is expected to hit the grid in 2020. Early this year New York State announced plans to spend 12 years building the infrastructure for a $6 billion offshore wind power industry. Hawaii has pledged to be powered entirely by renewable energy—in 2045. Atlanta’s goal is 2035 and San Francisco’s is 2030. Typically, plans to convert to sustainable energy stretch on for decades.
Alternatively, SRECs allow for a market mechanism to set the price of the solar generated electricity subsity. In this mechanism, a renewable energy production or consumption target is set, and the utility (more technically the Load Serving Entity) is obliged to purchase renewable energy or face a fine (Alternative Compliance Payment or ACP). The producer is credited for an SREC for every 1,000 kWh of electricity produced. If the utility buys this SREC and retires it, they avoid paying the ACP. In principle this system delivers the cheapest renewable energy, since the all solar facilities are eligible and can be installed in the most economic locations. Uncertainties about the future value of SRECs have led to long-term SREC contract markets to give clarity to their prices and allow solar developers to pre-sell and hedge their credits.
Renewable energy resources and significant opportunities for energy efficiency exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency, and technological diversification of energy sources, would result in significant energy security and economic benefits.[8] It would also reduce environmental pollution such as air pollution caused by burning of fossil fuels and improve public health, reduce premature mortalities due to pollution and save associated health costs that amount to several hundred billion dollars annually only in the United States.[21] 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 1 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.[22][23]
Index of solar energy articles List of concentrating solar thermal power companies List of photovoltaics companies List of photovoltaic power stations List of pioneering solar buildings List of rooftop photovoltaic installations List of solar car teams List of solar powered products List of solar thermal power stations People associated with solar power
Even with plans to grow as much as 80 percent over the next five years, the city expects to have plenty of energy from these renewable sources. (To be sure, about 2 percent of the time, the Georgetown utility draws electricity derived from fossil fuels. Ross says the city more than compensates at other times by selling excess renewable energy back to the grid—at a profit.)
Green Energy Corp’s™ Microgrid as a Service (MaaS) package is a cloud based, subscription service enabling third party developers to utilize GreenBus® and Green Energy Corp expertise in financing, building and deploying microgrids. Included in the MaaS package is the microgrid toolset comprised of software, design and engineering packages, equipment recommendations, construction methods, operations and maintenance support, and financial instruments all delivered from a hosted environment.

2010 was a record year for green energy investments. According to a report from Bloomberg New Energy Finance, nearly US $243 billion was invested in wind farms, solar power, electric cars, and other alternative technologies worldwide, representing a 30 percent increase from 2009 and nearly five times the money invested in 2004. China had $51.1 billion investment in clean energy projects in 2010, by far the largest figure for any country.[155]
Biofuels include a wide range of fuels which are derived from biomass. The term covers solid, liquid, and gaseous fuels.[73] Liquid biofuels include bioalcohols, such as bioethanol, and oils, such as biodiesel. Gaseous biofuels include biogas, landfill gas and synthetic gas. Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops. These include maize, sugarcane and, more recently, sweet sorghum. The latter crop is particularly suitable for growing in dryland conditions, and is being investigated by International Crops Research Institute for the Semi-Arid Tropics for its potential to provide fuel, along with food and animal feed, in arid parts of Asia and Africa.[74]
The typical cost factors for solar power include the costs of the modules, the frame to hold them, wiring, inverters, labour cost, any land that might be required, the grid connection, maintenance and the solar insolation that location will receive. Adjusting for inflation, it cost $96 per watt for a solar module in the mid-1970s. Process improvements and a very large boost in production have brought that figure down to 68 cents per watt in February 2016, according to data from Bloomberg New Energy Finance.[69] Palo Alto California signed a wholesale purchase agreement in 2016 that secured solar power for 3.7 cents per kilowatt-hour. And in sunny Dubai large-scale solar generated electricity sold in 2016 for just 2.99 cents per kilowatt-hour – "competitive with any form of fossil-based electricity — and cheaper than most."[70]
In cases of self consumption of the solar energy, the payback time is calculated based on how much electricity is not purchased from the grid. For example, in Germany, with electricity prices of 0.25 €/kWh and insolation of 900 kWh/kW, one kWp will save €225 per year, and with an installation cost of 1700 €/KWp the system cost will be returned in less than seven years.[91] However, in many cases, the patterns of generation and consumption do not coincide, and some or all of the energy is fed back into the grid. The electricity is sold, and at other times when energy is taken from the grid, electricity is bought. The relative costs and prices obtained affect the economics. In many markets, the price paid for sold PV electricity is significantly lower than the price of bought electricity, which incentivizes self consumption.[92] Moreover, separate self consumption incentives have been used in e.g. Germany and Italy.[92] Grid interaction regulation has also included limitations of grid feed-in in some regions in Germany with high amounts of installed PV capacity.[92][93] By increasing self consumption, the grid feed-in can be limited without curtailment, which wastes electricity.[94]
The stator is the “stationary” (hence its name) part of the machine and can have either a set of electrical windings producing an electromagnet or a set of permanent magnets within its design. The rotor is the part of the machine that “rotates”. Again, the rotor can have output coils that rotate or permanent magnets. Generally, generators and alternators used for wind turbine generators are defined by how they make generate their magnetism, either electromagnets or permanent magnets.

Green energy, however, utilizes energy sources that are readily available all over the world, including in rural and remote areas that don't otherwise have access to electricity. Advances in renewable energy technologies have lowered the cost of solar panels, wind turbines and other sources of green energy, placing the ability to produce electricity in the hands of the people rather than those of oil, gas, coal and utility companies.


Floatovoltaics are an emerging form of PV systems that float on the surface of irrigation canals, water reservoirs, quarry lakes, and tailing ponds. Several systems exist in France, India, Japan, Korea, the United Kingdom and the United States.[149][150][151][152] These systems reduce the need of valuable land area, save drinking water that would otherwise be lost through evaporation, and show a higher efficiency of solar energy conversion, as the panels are kept at a cooler temperature than they would be on land.[153] Although not floating, other dual-use facilities with solar power include fisheries.[154]
Shi Zhengrong has said that, as of 2012, unsubsidised solar power is already competitive with fossil fuels in India, Hawaii, Italy and Spain. He said "We are at a tipping point. No longer are renewable power sources like solar and wind a luxury of the rich. They are now starting to compete in the real world without subsidies". "Solar power will be able to compete without subsidies against conventional power sources in half the world by 2015".[75]
As suppliers of inverters for turbines good, bad, and just plain ugly, we have pretty well seen it all when it comes to turbine failure. We can tell you unequivocally that you get what you pay for. Depending on your sense of adventure that can be good or bad; if you plan to go cheap, plan on (you) being the manufacturer’s R&D department and test center. Being a really good do-it-yourselfer with an understanding of wind turbines, alternators, and all things electric will come in very handy too. Just in case you do not believe us, you can read about it in this Green Power Talk thread. There are more threads with similar content on the forum, just browse around a little.

flywheel energy storage, pumped-storage hydroelectricity is more usable in stationary applications (e.g. to power homes and offices). In household power systems, conversion of energy can also be done to reduce smell. For example, organic matter such as cow dung and spoilable organic matter can be converted to biochar. To eliminate emissions, carbon capture and storage is then used.
In the 1980s and early 1990s, most photovoltaic modules provided remote-area power supply, but from around 1995, industry efforts have focused increasingly on developing building integrated photovoltaics and power plants for grid connected applications (see photovoltaic power stations article for details). Currently the largest photovoltaic power plant in North America is the Nellis Solar Power Plant (15 MW).[24][25] There is a proposal to build a Solar power station in Victoria, Australia, which would be the world's largest PV power station, at 154 MW.[26][27] Other large photovoltaic power stations include the Girassol solar power plant (62 MW),[28] and the Waldpolenz Solar Park (40 MW).[29]
A hybrid system combines (C)PV and CSP with one another or with other forms of generation such as diesel, wind and biogas. The combined form of generation may enable the system to modulate power output as a function of demand or at least reduce the fluctuating nature of solar power and the consumption of non renewable fuel. Hybrid systems are most often found on islands.
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