As of 2011, small solar PV systems provide electricity to a few million households, and micro-hydro configured into mini-grids serves many more. Over 44 million households use biogas made in household-scale digesters for lighting and/or cooking, and more than 166 million households rely on a new generation of more-efficient biomass cookstoves.[26] 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] At the national level, at least 30 nations around the world already have renewable energy contributing more than 20% of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond, and some 120 countries have various policy targets for longer-term shares of renewable energy, including a 20% target of all electricity generated for the European Union by 2020. Some countries have much higher long-term policy targets of up to 100% renewables. Outside Europe, a diverse group of 20 or more other countries target renewable energy shares in the 2020–2030 time frame that range from 10% to 50%.[11]
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).

While a single dramatic victory against something like the dirty Keystone XL pipeline can be nice to imagine, the truth is this is how we’re going to win: fighting at every level and with every tool we’ve got. We can’t stop until governments and fossil fuel corporations finally get the message that we need to put our dirty past behind us and fully commit to a clean future that works for all of us moving forward. 
Renewable energy power plants do provide a steady flow of energy. For example, hydropower plants, ocean thermal plants, osmotic power plants all provide power at a regulated pace, and are thus available power sources at any given moment (even at night, windstill moments etc.). At present however, the number of steady-flow renewable energy plants alone is still too small to meet energy demands at the times of the day when the irregular producing renewable energy plants cannot produce power.
On most horizontal wind turbine farms, a spacing of about 6–10 times the rotor diameter is often upheld. However, for large wind farms distances of about 15 rotor diameters should be more economical, taking into account typical wind turbine and land costs. This conclusion has been reached by research[62] conducted by Charles Meneveau of the Johns Hopkins University,[63] and Johan Meyers of Leuven University in Belgium, based on computer simulations[64] that take into account the detailed interactions among wind turbines (wakes) as well as with the entire turbulent atmospheric boundary layer.
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]
Only a quarter of the worlds estimated hydroelectric potential of 14,000 TWh/year has been developed, the regional potentials for the growth of hydropower around the world are, 71% Europe, 75% North America, 79% South America, 95% Africa, 95% Middle East, 82% Asia Pacific. However, the political realities of new reservoirs in western countries, economic limitations in the third world and the lack of a transmission system in undeveloped areas, result in the possibility of developing 25% of the remaining potential before 2050, with the bulk of that being in the Asia Pacific area.[102] There is slow growth taking place in Western counties, but not in the conventional dam and reservoir style of the past. New projects take the form of run-of-the-river and small hydro, neither using large reservoirs. It is popular to repower old dams thereby increasing their efficiency and capacity as well as quicker responsiveness on the grid.[103] Where circumstances permit existing dams such as the Russell Dam built in 1985 may be updated with "pump back" facilities for pumped-storage which is useful for peak loads or to support intermittent wind and solar power. Countries with large hydroelectric developments such as Canada and Norway are spending billions to expand their grids to trade with neighboring countries having limited hydro.[104]
Since we mentioned maintenance: Consider that in a reasonably windy place a wind turbine can run 7000 hours or more per year. If it were a car, going at 50 km/h (30 mph), it would travel 350,000 km (or 200,000+ miles). That means you should plan for an annual inspection, and perform the needed maintenance (greasing for example), regardless of the recommendation of the manufacturer. It is just as important to inspect and maintain the tower annually. We know of a tower that collapsed because nuts worked themselves loose from their bolts over 2½ years time, no inspection nor maintenance were done during that time, ultimately leading to its undoing. Wind turbines and towers live in a very harsh environment. It is important to check for issues, such as loose bolts or tower guy wires that need re-tensioning, before they become a problem.

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]
So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. View the wind turbine animation to see how a wind turbine works or take a look inside.
A subtype of Darrieus turbine with straight, as opposed to curved, blades. The cycloturbine variety has variable pitch to reduce the torque pulsation and is self-starting.[33] The advantages of variable pitch are: high starting torque; a wide, relatively flat torque curve; a higher coefficient of performance; more efficient operation in turbulent winds; and a lower blade speed ratio which lowers blade bending stresses. Straight, V, or curved blades may be used.[34]
Green Pricing is an optional utility service for customers who want to help expand the production and distribution of renewable energy technologies. With green pricing, you do not have to change your electricity provider. Instead, customers choose to pay a premium on their electricity bill to cover the extra cost of purchasing clean, sustainable energy. As of March 2006, more than 600 utilities, electricity providers in 36 states offer a green pricing option.
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]
Geothermal power plants can operate 24 hours per day, providing base-load capacity, and the world potential capacity for geothermal power generation is estimated at 85 GW over the next 30 years. However, geothermal power is accessible only in limited areas of the world, including the United States, Central America, East Africa, Iceland, Indonesia, and the Philippines. The costs of geothermal energy have dropped substantially from the systems built in the 1970s.[10] Geothermal heat generation can be competitive in many countries producing geothermal power, or in other regions where the resource is of a lower temperature. Enhanced geothermal system (EGS) technology does not require natural convective hydrothermal resources, so it can be used in areas that were previously unsuitable for geothermal power, if the resource is very large. EGS is currently under research at the U.S. Department of Energy.
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]
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.
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]
In net metering the price of the electricity produced is the same as the price supplied to the consumer, and the consumer is billed on the difference between production and consumption. Net metering can usually be done with no changes to standard electricity meters, which accurately measure power in both directions and automatically report the difference, and because it allows homeowners and businesses to generate electricity at a different time from consumption, effectively using the grid as a giant storage battery. With net metering, deficits are billed each month while surpluses are rolled over to the following month. Best practices call for perpetual roll over of kWh credits.[97] Excess credits upon termination of service are either lost, or paid for at a rate ranging from wholesale to retail rate or above, as can be excess annual credits. In New Jersey, annual excess credits are paid at the wholesale rate, as are left over credits when a customer terminates service.[98]
We've had our system running for about 6 months now, whole process took a little over 2 months, other than submitting a form to our HOA and reviewing/signing some docs, Brio took care of the whole thing. The system works great, one month after it was running our power bill with Duke went to $0! Even in the summer when it's usually really high, honestly we were kinda skeptical but it's worked as promised. We're in NC and mainly worked with Brendan, he explained everything clearly and has been very responsive whenever we had questions.... read more
Jump up ^ Faunce, T. A.; Lubitz, W.; Rutherford, A. W. (Bill); MacFarlane, D.; Moore, G. F.; Yang, P.; Nocera, D. G; Moore, Tom A; Gregory, Duncan H; Fukuzumi, Shunichi; Yoon, Kyung B.; Armstrong, F. A.; Wasielewski, M. R.; Styring, S. (2013), "Energy and environment policy case for a global project on artificial photosynthesis", Energy & Environmental Science, 6 (3): 695–698, doi:10.1039/C3EE00063J, archived from the original on 16 August 2013
“Climate Change Helped Make California a Tinder Box for its Record-Setting Wildfires” • Camp Fire, which is devastating Sierra Nevada foothills, has become the most destructive wildfire in California’s history. By the evening of November 10, it had scorched 105,000 acres of land and killed 23 people, with more than 100 people still unaccounted for. [Quartz]
Several large-scale energy storage suggestions for the grid have been done. Worldwide there is over 100 GW of Pumped-storage hydroelectricity. This improves efficiency and decreases energy losses but a conversion to an energy storing mains electricity grid is a very costly solution. Some costs could potentially be reduced by making use of energy storage equipment the consumer buys and not the state. An example is batteries in electric cars that would double as an energy buffer for the electricity grid. However besides the cost, setting-up such a system would still be a very complicated and difficult procedure. Also, energy storage apparatus' as car batteries are also built with materials that pose a threat to the environment (e.g. Lithium). The combined production of batteries for such a large part of the population would still have environmental concerns. Besides car batteries however, other Grid energy storage projects make use of less polluting energy carriers (e.g. compressed air tanks and flywheel energy storage).
Technologies promote sustainable energy including renewable energy sources, such as hydroelectricity, solar energy, wind energy, wave power,[citation needed] geothermal energy, bioenergy, tidal power and also technologies designed to improve energy efficiency. Costs have decreased immensely throughout the years, and continue to fall. Increasingly, effective government policies support investor confidence and these markets are expanding. Considerable progress is being made in the energy transition from fossil fuels to ecologically sustainable systems, to the point where many studies support 100% renewable energy.
Through collaboration, smaller buyers can benefit from economies of scale, while larger buyers can continue to see cost benefits while achieving their renewable energy goals. Aggregation allows companies to procure in a mutually beneficial way with relatively little give and take. For that reason, RMI believes this marks “the beginning of a trend,” Haley said.  
A solar power tower uses an array of tracking reflectors (heliostats) to concentrate light on a central receiver atop a tower. Power towers can achieve higher (thermal-to-electricity conversion) efficiency than linear tracking CSP schemes and better energy storage capability than dish stirling technologies.[14] The PS10 Solar Power Plant and PS20 solar power plant are examples of this technology.
×