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.
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]
The primary obstacle that is preventing the large scale implementation of solar powered energy generation is the inefficiency of current solar technology. Currently, photovoltaic (PV) panels only have the ability to convert around 24% of the sunlight that hits them into electricity.[125] At this rate, solar energy still holds many challenges for widespread implementation, but steady progress has been made in reducing manufacturing cost and increasing photovoltaic efficiency. Both Sandia National Laboratories and the National Renewable Energy Laboratory (NREL), have heavily funded solar research programs. The NREL solar program has a budget of around $75 million [126] and develops research projects in the areas of photovoltaic (PV) technology, solar thermal energy, and solar radiation.[127] The budget for Sandia’s solar division is unknown, however it accounts for a significant percentage of the laboratory’s $2.4 billion budget.[128] Several academic programs have focused on solar research in recent years. The Solar Energy Research Center (SERC) at University of North Carolina (UNC) has the sole purpose of developing cost effective solar technology. In 2008, researchers at Massachusetts Institute of Technology (MIT) developed a method to store solar energy by using it to produce hydrogen fuel from water.[129] Such research is targeted at addressing the obstacle that solar development faces of storing energy for use during nighttime hours when the sun is not shining. In February 2012, North Carolina-based Semprius Inc., a solar development company backed by German corporation Siemens, announced that they had developed the world’s most efficient solar panel. The company claims that the prototype converts 33.9% of the sunlight that hits it to electricity, more than double the previous high-end conversion rate.[130] Major projects on artificial photosynthesis or solar fuels are also under way in many developed nations.[131]
Other renewable energy technologies are still under development, and include cellulosic ethanol, hot-dry-rock geothermal power, and marine energy.[156] These technologies are not yet widely demonstrated or have limited commercialization. Many are on the horizon and may have potential comparable to other renewable energy technologies, but still depend on attracting sufficient attention and research, development and demonstration (RD&D) funding.[156]
By participating in a green energy program a consumer may be having an effect on the energy sources used and ultimately might be helping to promote and expand the use of green energy. They are also making a statement to policy makers that they are willing to pay a price premium to support renewable energy. Green energy consumers either obligate the utility companies to increase the amount of green energy that they purchase from the pool (so decreasing the amount of non-green energy they purchase), or directly fund the green energy through a green power provider. If insufficient green energy sources are available, the utility must develop new ones or contract with a third party energy supplier to provide green energy, causing more to be built. However, there is no way the consumer can check whether or not the electricity bought is "green" or otherwise.
From 1978 to 1996, the National Renewable Energy Laboratory experimented with producing algae fuel in the "Aquatic Species Program."[112] A self-published article by Michael Briggs, at the University of New Hampshire Biofuels Group, offers estimates for the realistic replacement of all motor vehicle fuel with biofuels by utilizing algae that have a natural oil content greater than 50%, which Briggs suggests can be grown on algae ponds at wastewater treatment plants.[113] This oil-rich algae can then be extracted from the system and processed into biofuels, with the dried remainder further reprocessed to create ethanol. The production of algae to harvest oil for biofuels has not yet been undertaken on a commercial scale, but feasibility studies have been conducted to arrive at the above yield estimate. During the biofuel production process algae actually consumes the carbon dioxide in the air and turns it into oxygen through photosynthesis.[114] In addition to its projected high yield, algaculture— unlike food crop-based biofuels — does not entail a decrease in food production, since it requires neither farmland nor fresh water. Many companies are pursuing algae bio-reactors for various purposes, including scaling up biofuels production to commercial levels.[115][116]
You have read this far, and still want to install a wind turbine? Then it is time for a reality check: Most (some would say all) installed small wind turbines do abysmally poor in comparison with their energy production numbers as calculated above. That is the message from a number of studies, usually on behalf of governments that subsidize wind turbines. Do not just take our word for this, read it for yourself:

The New Zealand Parliamentary Commissioner for the Environment found that the solar PV would have little impact on the country's greenhouse gas emissions. The country already generates 80 percent of its electricity from renewable resources (primarily hydroelectricity and geothermal) and national electricity usage peaks on winter evenings whereas solar generation peaks on summer afternoons, meaning a large uptake of solar PV would end up displacing other renewable generators before fossil-fueled power plants.[127]

We now know that the electrical generator provides a means of energy conversion between the mechanical torque generated by the rotor blades, called the prime mover, and some electrical load. The mechanical connection of the wind turbine generator to the rotor blades is made through a main shaft which can be either a simple direct drive, or by using a gearbox to increase or decrease the generator speed relative to the rotational speed of the blades.
Energy harnessed by wind turbines is intermittent, and is not a "dispatchable" source of power; its availability is based on whether the wind is blowing, not whether electricity is needed. Turbines can be placed on ridges or bluffs to maximize the access of wind they have, but this also limits the locations where they can be placed.[72] In this way, wind energy is not a particularly reliable source of energy. However, it can form part of the energy mix, which also includes power from other sources. Notably, the relative available output from wind and solar sources is often inversely proportional (balancing)[citation needed]. Technology is also being developed to store excess energy, which can then make up for any deficits in supplies.
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.
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]
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]
In 2007, the US Congress directed the Department of Energy to report on ways to reduce water consumption by CSP. The subsequent report noted that dry cooling technology was available that, although more expensive to build and operate, could reduce water consumption by CSP by 91 to 95 percent. A hybrid wet/dry cooling system could reduce water consumption by 32 to 58 percent.[138] A 2015 report by NREL noted that of the 24 operating CSP power plants in the US, 4 used dry cooling systems. The four dry-cooled systems were the three power plants at the Ivanpah Solar Power Facility near Barstow, California, and the Genesis Solar Energy Project in Riverside County, California. Of 15 CSP projects under construction or development in the US as of March 2015, 6 were wet systems, 7 were dry systems, 1 hybrid, and 1 unspecified.
Since having the Peimar Solar Panels installed and listening to the advice of the owner I have saved a lot of money on my electric bill. Texas Solar Integrated did the work as quickly and efficiently as promised. If the panels look dirty, since I live around cement plants, I just get my high pressure water hose and spray them off. Thank you to this company and the installers. The owner or another contractor in the office is always ready to answer your questions before and after installation.... read more
In an electricity system without grid energy storage, generation from stored fuels (coal, biomass, natural gas, nuclear) must be go up and down in reaction to the rise and fall of solar electricity (see load following power plant). While hydroelectric and natural gas plants can quickly follow solar being intermittent due to the weather, coal, biomass and nuclear plants usually take considerable time to respond to load and can only be scheduled to follow the predictable variation. Depending on local circumstances, beyond about 20–40% of total generation, grid-connected intermittent sources like solar tend to require investment in some combination of grid interconnections, energy storage or demand side management. Integrating large amounts of solar power with existing generation equipment has caused issues in some cases. For example, in Germany, California and Hawaii, electricity prices have been known to go negative when solar is generating a lot of power, displacing existing baseload generation contracts.[107][108]
Small wind turbines may be used for a variety of applications including on- or off-grid residences, telecom towers, offshore platforms, rural schools and clinics, remote monitoring and other purposes that require energy where there is no electric grid, or where the grid is unstable. Small wind turbines may be as small as a fifty-watt generator for boat or caravan use. Hybrid solar and wind powered units are increasingly being used for traffic signage, particularly in rural locations, as they avoid the need to lay long cables from the nearest mains connection point.[60] The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) defines small wind turbines as those smaller than or equal to 100 kilowatts.[61] Small units often have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind.
Perfect for camping tailgating or when you need Perfect for camping tailgating or when you need power on the go. The FIRMAN P01001 generator features 1050 starting Watts and 1300 running watts. Power is supplied by our Max Pro Series 80cc FIRMAN engine which runs cool and efficient thanks to its Phoenix Fat Head Block. Our Whisper Series ...  More + Product Details Close
Usually however, renewable energy is derived from the mains electricity grid. This means that energy storage is mostly not used, as the mains electricity grid is organised to produce the exact amount of energy being consumed at that particular moment. Energy production on the mains electricity grid is always set up as a combination of (large-scale) renewable energy plants, as well as other power plants as fossil-fuel power plants and nuclear power. This combination however, which is essential for this type of energy supply (as e.g. wind turbines, solar power plants etc.) can only produce when the wind blows and the sun shines. This is also one of the main drawbacks of the system as fossil fuel powerplants are polluting and are a main cause of global warming (nuclear power being an exception). Although fossil fuel power plants too can be made emissionless (through carbon capture and storage), as well as renewable (if the plants are converted to e.g. biomass) the best solution is still to phase out the latter power plants over time. Nuclear power plants too can be more or less eliminated from their problem of nuclear waste through the use of nuclear reprocessing and newer plants as fast breeder and nuclear fusion plants.
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.

Environmental impact of wind power includes effect on wildlife, but can be mitigated if proper monitoring and mitigation strategies are implemented.[76] Thousands of birds, including rare species, have been killed by the blades of wind turbines,[77] though wind turbines contribute relatively insignificantly to anthropogenic avian mortality. For every bird killed by a wind turbine in the US, nearly 500,000 are killed by each of feral cats and buildings.[78] In comparison, conventional coal fired generators contribute significantly more to bird mortality, by incineration when caught in updrafts of smoke stacks and by poisoning with emissions byproducts (including particulates and heavy metals downwind of flue gases). Further, marine life is affected by water intakes of steam turbine cooling towers (heat exchangers) for nuclear and fossil fuel generators, by coal dust deposits in marine ecosystems (e.g. damaging Australia's Great Barrier Reef) and by water acidification from combustion monoxides.
Renewable energy (and energy efficiency) are no longer niche sectors that are promoted only by governments and environmentalists. The increased levels of investment and the fact that much of the capital is coming from more conventional financial actors suggest that sustainable energy options are now becoming mainstream.[63] An example of this would be The Alliance to Save Energy's Project with Stahl Consolidated Manufacturing, (Huntsville, Alabama, USA) (StahlCon 7), a patented generator shaft designed to reduce emissions within existing power generating systems, granted publishing rights to the Alliance in 2007.
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.
Solar and wind are Intermittent energy sources that supply electricity 10-40% of the time. To compensate for this characteristic, it is common to pair their production with already existing hydroelectricity or natural gas generation. In regions where this isn't available, wind and solar can be paired with significantly more expensive pumped-storage hydroelectricity.
Based on REN21's 2017 report, renewables contributed 19.3% to humans' global energy consumption and 24.5% to their generation of electricity in 2015 and 2016, respectively. This energy consumption is divided as 8.9% coming from traditional biomass, 4.2% as heat energy (modern biomass, geothermal and solar heat), 3.9% hydro electricity and 2.2% is electricity from wind, solar, geothermal, and biomass. Worldwide investments in renewable technologies amounted to more than US$286 billion in 2015, with countries such as China and the United States heavily investing in wind, hydro, solar and biofuels.[5] Globally, there are an estimated 7.7 million jobs associated with the renewable energy industries, with solar photovoltaics being the largest renewable employer.[6] As of 2015 worldwide, more than half of all new electricity capacity installed was renewable.[7]
One issue that has often raised concerns is the use of cadmium (Cd), a toxic heavy metal that has the tendency to accumulate in ecological food chains. It is used as semiconductor component in CdTe solar cells and as buffer layer for certain CIGS cells in the form of CdS.[141] The amount of cadmium used in thin-film PV modules is relatively small (5–10 g/m²) and with proper recycling and emission control techniques in place the cadmium emissions from module production can be almost zero. Current PV technologies lead to cadmium emissions of 0.3–0.9 microgram/kWh over the whole life-cycle.[121] Most of these emissions arise through the use of coal power for the manufacturing of the modules, and coal and lignite combustion leads to much higher emissions of cadmium. Life-cycle cadmium emissions from coal is 3.1 microgram/kWh, lignite 6.2, and natural gas 0.2 microgram/kWh.

This sets sustainable energy apart from other renewable energy terminology such as alternative energy by focusing on the ability of an energy source to continue providing energy. Sustainable energy can produce some pollution of the environment, as long as it is not sufficient to prohibit heavy use of the source for an indefinite amount of time. Sustainable energy is also distinct from low-carbon energy, which is sustainable only in the sense that it does not add to the CO2 in the atmosphere.
Solar Power Rocks provides free comprehensive guides to solar policy and incentives for all 50 states and the District of Columbia, along with hundreds of helpful and informative articles about recent solar news and general information related to home solar power. For media inquiries, general questions, or to report an error, you can reach us here.
It is hard to beat the advantages of solar: No moving parts. Warranties of 25 years are common for PV modules. No maintenance, other than the occasional hosing-off if you live in a dusty place. The installed price of a 6 kW wind turbine on a good height tower is about $50,000 (and we are not even counting the money you are going to sink into maintenance of that wind turbine). At the time of this writing, half that money will buy you about 7 kW of installed solar panels. In our not-so-sunny Ottawa location those solar modules will produce around 8,000 kWh of electrical energy per average year, and they will do that for 30 years or more.
Jump up ^ Schröder, K.-P.; Smith, R.C. (2008). "Distant future of the Sun and Earth revisited". Monthly Notices of the Royal Astronomical Society. 386 (1): 155–163. arXiv:0801.4031. Bibcode:2008MNRAS.386..155S. doi:10.1111/j.1365-2966.2008.13022.x. See also Palmer, J. (2008). "Hope dims that Earth will survive Sun's death". New Scientist. Retrieved 24 March 2008.

The energy in the wind goes up with the cube of the wind speed. Double the wind speed and you have 2 * 2 * 2 = 8 times the energy! Sit back and let the full weight of that sink in for a moment: It means that even a small difference in annual average wind speed will make a BIG difference in how much your wind turbine will produce: Putting that turbine in a place that has just 10% more wind will net you 1.1 * 1.1 * 1.1 = 1.33 = a full 33% more energy!
Compact Linear Fresnel Reflectors are CSP-plants which use many thin mirror strips instead of parabolic mirrors to concentrate sunlight onto two tubes with working fluid. This has the advantage that flat mirrors can be used which are much cheaper than parabolic mirrors, and that more reflectors can be placed in the same amount of space, allowing more of the available sunlight to be used. Concentrating linear fresnel reflectors can be used in either large or more compact plants.[16][17]