Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country's automotive fuel. As a result of this, together with the exploitation of domestic deep water oil sources, Brazil, which years ago had to import a large share of the petroleum needed for domestic consumption, recently reached complete self-sufficiency in oil.[36][37][38]
Consumers throughout the United States have a third green power option: Renewable Energy Certificates (RECs or sometimes "green tags"). A REC represents the environmental attributes or benefits of renewable electricity generation (usually one credit = one kilowatt-hour). RECs can be purchased in almost any quantity and are usually available from someone other than your electricity provider. What you pay for is the benefit of adding clean, renewable energy generation to the regional or national electricity grid. The overall environmental benefit of purchasing a green pricing or green marketing product versus RECs is exactly the same. RECs provide a "green" option for people in any state, but are ideal for people who live in states where green pricing and green marketing options are not available. 
With Georgetown emerging as a brave new model for a renewable city, it makes sense to ask if others can achieve the same magical balance of more power, less pollution and lower costs. In fact, cities ranging from Orlando to St. Louis to San Francisco to Portland, Oregon, have pledged to run entirely on renewable energy. Those places are much larger than Georgetown, of course, and no one would expect misty Portland to power a light bulb for long with solar energy, which is crucial to Georgetown’s success. But beyond its modest size, abundant sunshine and archetype-busting mayor, Georgetown has another edge, one that’s connected to a cherished Lone Star ideal: freedom.

Marine energy (also sometimes referred to as ocean energy) refers to the energy carried by ocean waves, tides, salinity, and ocean temperature differences. The movement of water in the world's oceans creates a vast store of kinetic energy, or energy in motion. This energy can be harnessed to generate electricity to power homes, transport and industries. The term marine energy encompasses both wave power – power from surface waves, and tidal power – obtained from the kinetic energy of large bodies of moving water. Reverse electrodialysis (RED) is a technology for generating electricity by mixing fresh river water and salty sea water in large power cells designed for this purpose; as of 2016 it is being tested at a small scale (50 kW). Offshore wind power is not a form of marine energy, as wind power is derived from the wind, even if the wind turbines are placed over water. The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around the world.[165]
For several years, worldwide growth of solar PV was driven by European deployment, but has since shifted to Asia, especially China and Japan, and to a growing number of countries and regions all over the world, including, but not limited to, Australia, Canada, Chile, India, Israel, Mexico, South Africa, South Korea, Thailand, and the United States.
Solar electricity is inherently variable and predictable by time of day, location, and seasons. In addition solar is intermittent due to day/night cycles and unpredictable weather. How much of a special challenge solar power is in any given electric utility varies significantly. In a summer peak utility, solar is well matched to daytime cooling demands. In winter peak utilities, solar displaces other forms of generation, reducing their capacity factors.

The Nomad 20 Solar Panel combines highly efficient The Nomad 20 Solar Panel combines highly efficient monocrystalline technology in a foldable portable plug-and-play form. With a built-in junction box and innovative smart chip the Nomad 20 can directly charge handheld USB and 12-Volt devices directly from the sun just as fast as the wall. Combine the Nomad 20 ...  More + Product Details Close
Turbines used in residential applications can range in size from 400 Watts to 100 kW (100 kW for very large loads), depending on the amount of electricity you want to generate. For residential applications, you should establish an energy budget and see whether financial incentives are available. This information will help determine the turbine size you will need. Because energy efficiency is usually less expensive than energy production, making your house more energy efficient will probably be more cost effective and will reduce the size of the wind turbine you need (see How Can I Make My Home More Energy Efficient?). Wind turbine manufacturers, dealers, and installers can help you size your system based on your electricity needs and the specifics of your local wind resource and micro-siting.

By 2040, renewable energy is projected to equal coal and natural gas electricity generation. Several jurisdictions, including Denmark, Germany, the state of South Australia and some US states have achieved high integration of variable renewables. For example, in 2015 wind power met 42% of electricity demand in Denmark, 23.2% in Portugal and 15.5% in Uruguay. Interconnectors enable countries to balance electricity systems by allowing the import and export of renewable energy. Innovative hybrid systems have emerged between countries and regions.[27]
Moving towards energy sustainability will require changes not only in the way energy is supplied, but in the way it is used, and reducing the amount of energy required to deliver various goods or services is essential. Opportunities for improvement on the demand side of the energy equation are as rich and diverse as those on the supply side, and often offer significant economic benefits.[60]
In stand alone PV systems batteries are traditionally used to store excess electricity. With grid-connected photovoltaic power system, excess electricity can be sent to the electrical grid. Net metering and feed-in tariff programs give these systems a credit for the electricity they produce. This credit offsets electricity provided from the grid when the system cannot meet demand, effectively trading with the grid instead of storing excess electricity. Credits are normally rolled over from month to month and any remaining surplus settled annually.[111] When wind and solar are a small fraction of the grid power, other generation techniques can adjust their output appropriately, but as these forms of variable power grow, additional balance on the grid is needed. As prices are rapidly declining, PV systems increasingly use rechargeable batteries to store a surplus to be later used at night. Batteries used for grid-storage stabilize the electrical grid by leveling out peak loads usually for several minutes, and in rare cases for hours. In the future, less expensive batteries could play an important role on the electrical grid, as they can charge during periods when generation exceeds demand and feed their stored energy into the grid when demand is higher than generation.

A Wind Turbine Generator is what makes your electricity by converting mechanical energy into electrical energy. Lets be clear here, they do not create energy or produce more electrical energy than the amount of mechanical energy being used to spin the rotor blades. The greater the “load”, or electrical demand placed on the generator, the more mechanical force is required to turn the rotor. This is why generators come in different sizes and produce differing amounts of electricity.

The waste we generate ends up in landfills, where it decomposes and produces landfill gas made of approximately 50 percent methane. This gas can be captured and used to fuel electric generators. Since large landfills must burn off this gas to reduce the hazards arising from gas buildup, this method of renewable energy is one of the most successful.

While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas and developing countries, where energy is often crucial in human development.[13] Former United Nations Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity.[14] As most of renewables provide electricity, renewable energy deployment is often applied in conjunction with further electrification, which has several benefits: Electricity can be converted to heat (where necessary generating higher temperatures than fossil fuels), can be converted into mechanical energy with high efficiency and is clean at the point of consumption.[15][16] In addition to that electrification with renewable energy is much more efficient and therefore leads to a significant reduction in primary energy requirements, because most renewables don't have a steam cycle with high losses (fossil power plants usually have losses of 40 to 65%).[17]
Solar water heating makes an important contribution to renewable heat in many countries, most notably in China, which now has 70% of the global total (180 GWth). Most of these systems are installed on multi-family apartment buildings and meet a portion of the hot water needs of an estimated 50–60 million households in China. Worldwide, total installed solar water heating systems meet a portion of the water heating needs of over 70 million households. The use of biomass for heating continues to grow as well. In Sweden, national use of biomass energy has surpassed that of oil. Direct geothermal for heating is also growing rapidly.[28] The newest addition to Heating is from Geothermal Heat Pumps which provide both heating and cooling, and also flatten the electric demand curve and are thus an increasing national priority[29][30] (see also Renewable thermal energy).
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Biomass, biogas and biofuels are burned to produce heat/power and in doing so harm the environment. Pollutants such as sulphurous oxides (SOx), nitrous oxides (NOx), and particulate matter (PM) are produced from the combustion of biomass; the World Health Organisation estimates that 7 million premature deaths are caused each year by air pollution.[77] Biomass combustion is a major contributor.[77][78][79]
At Bodine-Scott, our renewable energy options have helped dozens of local homes and businesses reduce their utility bills and any negative environmental impact from the use of traditional energy sources. Our technicians are NABCEP-certified experts, and we keep all of our staff informed and up to date on the latest developments in the solar industries. Our average customer sees a 50 percent reduction in utility costs, to say nothing of the invaluable reduction in environmental impact that comes from using clean energy. If you are serious about making an investment in the future of your home and the Earth, contact us today to speak with one of our renewable energy experts.
Concentrated solar power plants may use thermal storage to store solar energy, such as in high-temperature molten salts. These salts are an effective storage medium because they are low-cost, have a high specific heat capacity, and can deliver heat at temperatures compatible with conventional power systems. This method of energy storage is used, for example, by the Solar Two power station, allowing it to store 1.44 TJ in its 68 m³ storage tank, enough to provide full output for close to 39 hours, with an efficiency of about 99%.[110]
Which is to say that Ross and his co-workers had options. And the city was free to take advantage of them because of a rather unusual arrangement: Georgetown itself owns the utility company that serves the city. So officials there, unlike those in most cities, were free to negotiate with suppliers. When they learned that rates for wind power could be guaranteed for 20 years and solar for 25 years, but natural gas for only seven years, the choice, Ross says, was a “no-brainer.”
Jump up ^ Artificial photosynthesis as a frontier technology for energy sustainability. Thomas Faunce, Stenbjorn Styring, Michael R. Wasielewski, Gary W. Brudvig, A. William Rutherford, Johannes Messinger, Adam F. Lee, Craig L. Hill, Huub deGroot, Marc Fontecave, Doug R. MacFarlane, Ben Hankamer, Daniel G. Nocera, David M. Tiede, Holger Dau, Warwick Hillier, Lianzhou Wang and Rose Amal. Energy Environ. Sci., 2013, Advance Article doi:10.1039/C3EE40534F
Photovoltaics (PV) uses solar cells assembled into solar panels to convert sunlight into electricity. It's a fast-growing technology doubling its worldwide installed capacity every couple of years. PV systems range from small, residential and commercial rooftop or building integrated installations, to large utility-scale photovoltaic power station. The predominant PV technology is crystalline silicon, while thin-film solar cell technology accounts for about 10 percent of global photovoltaic deployment. In recent years, PV technology has improved its electricity generating efficiency, reduced the installation cost per watt as well as its energy payback time, and has reached grid parity in at least 30 different markets by 2014.[115] Financial institutions are predicting a second solar "gold rush" in the near future.[116][117][118]
The International Renewable Energy Agency (IRENA) is an intergovernmental organization for promoting the adoption of renewable energy worldwide. It aims to provide concrete policy advice and facilitate capacity building and technology transfer. IRENA was formed on 26 January 2009, by 75 countries signing the charter of IRENA.[145] As of March 2010, IRENA has 143 member states who all are considered as founding members, of which 14 have also ratified the statute.[146]
The energy number that is left over should be a good approximation of what you can expect from that VAWT. Compare the resulting numbers with those mentioned in just about all sales brochures of VAWT type turbines and it should be immediately clear that their marketing people are smoking The Good Stuff. There is no relation to physical reality in their numbers, they are consistently much too high. Keep in mind that the energy production numbers calculated here are ‘best case’; for a turbine in nice, smooth air. Most VAWTs are placed very close to the ground, or on buildings, where there is little wind and lots of turbulence. Under those conditions they will do much, much worse than predicted.
Large three-bladed horizontal-axis wind turbines (HAWT), with the blades upwind of the tower produce the overwhelming majority of windpower in the world today. These turbines have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind. Small turbines are pointed by a simple wind vane, while large turbines generally use a wind sensor coupled with a yaw system. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator.[25] Some turbines use a different type of generator suited to slower rotational speed input. These don't need a gearbox, and are called direct-drive, meaning they couple the rotor directly to the generator with no gearbox in between. While permanent magnet direct-drive generators can be more costly due to the rare earth materials required, these gearless turbines are sometimes preferred over gearbox generators because they "eliminate the gear-speed increaser, which is susceptible to significant accumulated fatigue torque loading, related reliability issues, and maintenance costs."[26]
There is one more area where buyers may get a false sense of security: Several states in the US have lists of “approved” wind turbines for their rebate programs. An example of this is the California list. The problem is that approval for this list, and the performance data provided (such as rated power and energy production) are essentially self-certified. The less-scrupulous manufacturers can ‘manufacture’ data and submit it under the pretence that it was measured.  The only value of those lists is in telling you what rebates are available, they do not provide reliable turbine information.
Setting up a solar electric system is easy. The new source of power will integrate seamlessly with your existing utilities. Apart from settimg up the solar energy equipment, there will be no need to reconfigure or rewire your home. Our offerings include several pre-engineered, packaged systems for both residential and commercial applications, so there’s sure to be something that fits the needs of your home or business. Most solar panels last about 30 years, which means you will see the benefits of this new source of energy for decades to come.
These high strength magnets are usually made from rare earth materials such as neodymium iron (NdFe), or samarium cobalt (SmCo) eliminating the need for the field windings to provide a constant magnetic field, leading to a simpler, more rugged construction. Wound field windings have the advantage of matching their magnetism (and therefore power) with the varying wind speed but require an external energy source to generate the required magnetic field.
Interest in recycling blades varies in different markets and depends on the waste legislation and local economics. A challenge in recycling blades is related to the composite material, which is made of a thermosetting matrix and glass fibers or a combination of glass and carbon fibers. Thermosetting matrix cannot be remolded to form new composites. So the options are either to reuse the blade and the composite material elements as they are found in the blade or to transform the composite material into a new source of material. In Germany, wind turbine blades are commercially recycled as part of an alternative fuel mix for a cement factory.
A photovoltaic system converts light into electrical direct current (DC) by taking advantage of the photoelectric effect.[51] Solar PV has turned into a multi-billion, fast-growing industry, continues to improve its cost-effectiveness, and has the most potential of any renewable technologies together with CSP.[52][53] Concentrated solar power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Commercial concentrated solar power plants were first developed in the 1980s. CSP-Stirling has by far the highest efficiency among all solar energy technologies.
Small-scale turbines are expensive (one manufacturer says a typical system costs $40,000 to $60,000 to install), though some of that outlay can be offset by federal and local tax credits. Experts recommend that you buy one certified by the Small Wind Certification Council. Turbine manufacturers include Bergey Wind Power, Britwind and Xzeres Wind; look on their websites for local dealers.
Energy storage is a collection of methods used to store electrical energy on an electrical power grid, or off it. Electrical energy is stored during times when production (especially from intermittent power plants such as renewable electricity sources such as wind power, tidal power, solar power) exceeds consumption, and returned to the grid when production falls below consumption. Pumped-storage hydroelectricity is used for more than 90% of all grid power storage. Costs of lithium ion batteries are dropping rapidly, and are increasingly being deployed as fast acting sources of grid power (i.e. operating reserve) and for domestic storage.
The Desert Sunlight Solar Farm is a 550 MW power plant in Riverside County, California, that uses thin-film CdTe-modules made by First Solar.[41] As of November 2014, the 550 megawatt Topaz Solar Farm was the largest photovoltaic power plant in the world. This was surpassed by the 579 MW Solar Star complex. The current largest photovoltaic power station in the world is Longyangxia Dam Solar Park, in Gonghe County, Qinghai, China.
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