Eight solar panels and one measly little wind generator supplied all the power we used. We bolted the pole that supported the wind generator to a wall of our house, which, sound-wise, turned the roof of the house into one big drumhead.  Oops! Live and learn. And when the wind REALLY blew—which was often—the thing broke. The manufacturer replaced the main unit several times before we gave up on wind power.
Japan and China have national programs aimed at commercial scale Space-Based Solar Power (SBSP). The China Academy of Space Technology (CAST) won the 2015 International SunSat Design Competition with this video of their Multi-Rotary Joint design. Proponents of SBSP claim that Space-Based Solar Power would be clean, constant, and global, and could scale to meet all planetary energy demand.[56] A recent multi-agency industry proposal (echoing the 2008 Pentagon recommendation) won the SECDEF/SECSTATE/USAID Director D3 (Diplomacy, Development, Defense) Innovation Challenge.[57]
Solar energy is the cleanest and most abundant renewable energy source available, and the U.S. has some of the richest solar resources in the world. Solar technologies can harness this energy for a variety of uses, including generating electricity, providing light or a comfortable interior environment, and heating water for domestic, commercial, or industrial use.
Renewable energy and energy efficiency are sometimes said to be the "twin pillars" of sustainable energy policy. Both resources must be developed in order to stabilize and reduce carbon dioxide emissions. Efficiency slows down energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too fast, renewable energy development will chase a receding target. A recent historical analysis has demonstrated that the rate of energy efficiency improvements has generally been outpaced by the rate of growth in energy demand, which is due to continuing economic and population growth. As a result, despite energy efficiency gains, total energy use and related carbon emissions have continued to increase. Thus, given the thermodynamic and practical limits of energy efficiency improvements, slowing the growth in energy demand is essential.[61] However, unless clean energy supplies come online rapidly, slowing demand growth will only begin to reduce total emissions; reducing the carbon content of energy sources is also needed. Any serious vision of a sustainable energy economy thus requires commitments to both renewables and efficiency.[62]
If you can turn a wrench and operate an electric drill, you can build this simple generator in two days: one day for chasing down parts, and one day for assembling the components. The four major components include a vehicle alternator with a built-in voltage regulator, a General Motors (GM) fan and clutch assembly (I used one from a 1988 GM 350 motor), a tower or pole on which to mount the generator (15 feet of used 2-inch tubing cost me $20), and the metal to build a bracket for mounting the generator on the tower or pole. If you’re a Ford guy or a Mopar gal, that’s fine — just make sure your alternator has a built-in voltage regulator. You’ll also need some electrical cable or wires to hook the alternator up to your storage batteries. I used 8-gauge, 3-conductor cable pilfered from the oil patch. (And they said the transition from fossil fuels to renewables would take years. Pfft!)
Commercial concentrated solar power plants were first developed in the 1980s. As the cost of solar electricity has fallen, the number of grid-connected solar PV systems has grown into the millions and utility-scale solar power stations with hundreds of megawatts are being built. Solar PV is rapidly becoming an inexpensive, low-carbon technology to harness renewable energy from the Sun.
We harness the earth’s most abundant resources – the strength of the wind, the heat of the sun and the force of water – to power the world’s biggest economies and the most remote communities. Combining onshore and offshore wind, hydro and innovative technologies, GE Renewable Energy has installed more than 400+ gigawatts capacity globally to make the world work better and cleaner.

Green marketing is the sale of green power in competitive markets, where consumers have the option to choose from a variety of suppliers and service offerings, much like they can choose between long-distance telephone carriers. The key difference between green marketing and green pricing is that with green marketing, you are actually switching electricity providers. 
Green power is a subset of renewable energy and represents those renewable energy resources and technologies that provide the highest environmental benefit. The U.S. Environmental Protection Agency defines green power as electricity produced from solar, wind, geothermal, biogas, biomass and low-impact small hydroelectric sources. Customers often buy green power for avoided environmental impacts and its greenhouse gas reduction benefits.[9]

^ Jump up to: a b c Fridleifsson,, Ingvar B.; Bertani, Ruggero; Huenges, Ernst; Lund, John W.; Ragnarsson, Arni; Rybach, Ladislaus (11 February 2008). O. Hohmeyer and T. Trittin, ed. "The possible role and contribution of geothermal energy to the mitigation of climate change" (PDF). Luebeck, Germany: 59–80. Archived from the original (pdf) on 22 July 2011. Retrieved 6 April 2009.
A Darrieus type vertical axis wind turbine (the egg-beater type) can in theory work almost as good as a horizontal axis turbine. Actual measurement of one of the better designs out there, the UGE VisionAir5, does not bear that out though: It measures in at a pitiful 11% efficiency at 11 m/s wind speed, while a Bergey Excel-6 HAWT clocks in at 22% efficiency for that same wind speed, twice as much. You can read about it in Paul Gipe’s article.  Besides efficiency issues, a Darrieus VAWT unfortunately has a number of inherent issues that put them at a disadvantage: Since they are usually tall and relatively narrow structures the bending forces on their main bearing (at the bottom) are very large. There are similar issues with the forces on the blades. This means that to make a reliable vertical axis turbine takes more material, and more expensive materials, in comparison to a horizontal type turbine. For comparison, that same UGE VisionAir5 weighs 756 kg vs. the Bergey Excel-6 at 350 kg. Keep in mind that the UGE turbine only sweeps about half the area of the Bergey, the latter is a much larger turbine! This makes VAWTs inherently more expensive, or less reliable, or both.
Wind-to-rotor efficiency (including rotor blade friction and drag) are among the factors impacting the final price of wind power.[16] Further inefficiencies, such as gearbox losses, generator and converter losses, reduce the power delivered by a wind turbine. To protect components from undue wear, extracted power is held constant above the rated operating speed as theoretical power increases at the cube of wind speed, further reducing theoretical efficiency. In 2001, commercial utility-connected turbines deliver 75% to 80% of the Betz limit of power extractable from the wind, at rated operating speed.[17][18][needs update]
Outline of energy Energy Units Conservation of energy Energetics Energy transformation Energy condition Energy transition Energy level Energy system Mass Negative mass Mass–energy equivalence Power Thermodynamics Quantum thermodynamics Laws of thermodynamics Thermodynamic system Thermodynamic state Thermodynamic potential Thermodynamic free energy Irreversible process Thermal reservoir Heat transfer Heat capacity Volume (thermodynamics) Thermodynamic equilibrium Thermal equilibrium Thermodynamic temperature Isolated system Entropy Free entropy Entropic force Negentropy Work Exergy Enthalpy

List of books about renewable energy List of countries by electricity production from renewable sources List of geothermal power stations Lists of hydroelectric power stations List of largest hydroelectric power stations List of people associated with renewable energy List of renewable energy companies by stock exchange List of renewable energy organizations List of renewable energy topics by country List of U.S. states by electricity production from renewable sources

Taken together, the generation and distribution of electric power in the United States is an astonishingly complex undertaking. Utilities may generate their own power or buy it from other utilities; that power travels over a grid of transformers and high- and low-voltage lines to your house. Ownership of utilities varies from nonprofits to cooperatives to for-profits. Federal regulators ultimately oversee the grid. Amazingly, when you flip a switch, electricity is there.
Besides getting a working product, the one measure you are after as a small wind turbine owner is how much electrical energy it will produce for your location. Hopefully by now you know the annual average wind speed for the height that you are planning to put your turbine at, and you have selected a site with little turbulence. Forget about the manufacturer’s claims; it turns out that the best predictors for turbine energy production are the diameter and average wind speed. Here is an equation that will calculate approximate annual average energy production for a grid-tie horizontal axis turbine of reasonable efficiency:
Besides the greening of fossil fuel and nuclear power plants, another option is the distribution and immediate use of power from solely renewable sources. In this set-up energy storage is again not necessary. For example, TREC has proposed to distribute solar power from the Sahara to Europe. Europe can distribute wind and ocean power to the Sahara and other countries. In this way, power is produced at any given time as at any point of the planet as the sun or the wind is up or ocean waves and currents are stirring. This option however is probably not possible in the short-term, as fossil fuel and nuclear power are still the main sources of energy on the mains electricity net and replacing them will not be possible overnight.
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As competition in the wind market increases, companies are seeking ways to draw greater efficiency from their designs. One of the predominant ways wind turbines have gained performance is by increasing rotor diameters, and thus blade length. Retrofitting current turbines with larger blades mitigates the need and risks associated with a system-level redesign. As the size of the blade increases, its tendency to deflect also increases. Thus, from a materials perspective, the stiffness-to-weight is of major importance. As the blades need to function over a 100 million load cycles over a period of 20–25 years, the fatigue life of the blade materials is also of utmost importance. By incorporating carbon fiber into parts of existing blade systems, manufacturers may increase the length of the blades without increasing their overall weight. For instance, the spar cap, a structural element of a turbine blade, commonly experiences high tensile loading, making it an ideal candidate to utilize the enhanced tensile properties of carbon fiber in comparison to glass fiber.[47] Higher stiffness and lower density translates to thinner, lighter blades offering equivalent performance. In a 10 (MW) turbine—which will become more common in offshore systems by 2021—blades may reach over 100 m in length and weigh up to 50 metric tons when fabricated out of glass fiber. A switch to carbon fiber in the structural spar of the blade yields weight savings of 20 to 30 percent, or approximately 15 metric tons.[48]
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.
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