Dale Ross, the mayor of Georgetown, Texas, has a big smile, a big handshake and a big personality. In last year’s election, he won big, with 72 percent of the vote. The key to his success? “Without being too self-reflective,” he says, “I just like people.” He’s a Republican, and his priorities are party staples: go light on regulation, be tough on crime, keep taxes low. But the thing that is winning him international renown is straight out of the liberal playbook—green power. Thanks to his (big) advocacy, Georgetown (pop. 67,000) last year became the largest city in the United States to be powered entirely by renewable energy.
The first three are active solar systems, which use mechanical or electrical devices that convert the sun's heat or light to another form of usable energy. Passive solar buildings are designed and oriented to collect, store, and distribute the heat energy from sunlight to maintain the comfort of the occupants without the use of moving parts or electronics.
“New Wind May Be Cheaper than Old, Reliable Coal” • Wind farms have cost less to build and operate than coal-fired power plants for some time. The trend of lower costs for renewables has crossed a threshold: it is sometimes cheaper to build a brand new wind facility than keep an old coal plant burning, according to Lazard Ltd. [Casper Star-Tribune Online]
Currently, flying manned electric aircraft are mostly experimental demonstrators, though many small unmanned aerial vehicles are powered by batteries. Electrically powered model aircraft have been flown since the 1970s, with one report in 1957.[186][187] The first man-carrying electrically powered flights were made in 1973.[188] Between 2015–2016, a manned, solar-powered plane, Solar Impulse 2, completed a circumnavigation of the Earth.[189]
Wind power - Air flow on the earth's surface can be used to push turbines, with stronger winds producing more energy. High-altitude sites and areas just offshore tend to provide the best conditions for capturing the strongest winds. According to a 2009 study, a network of land-based, 2.5-megawatt wind turbines in rural areas operating at just 20% of their rated capacity could supply 40 times the current worldwide consumption of energy.
Several initiatives are being proposed to mitigate distribution problems. First and foremost, the most effective way to reduce USA’s CO2 emissions and slow global warming is through conservation efforts. Opponents of the current US electrical grid have also advocated for decentralizing the grid. This system would increase efficiency by reducing the amount of energy lost in transmission. It would also be economically viable as it would reduce the amount of power lines that will need to be constructed in the future to keep up with demand. Merging heat and power in this system would create added benefits and help to increase its efficiency by up to 80-90%. This is a significant increase from the current fossil fuel plants which only have an efficiency of 34%.[92]
†Offer is available to Texas residential customers who enroll using the Promotion Code “NIGHTSFREE”. Plan bills a monthly Base Charge, an Energy Charge, and passes through Utility Transmission and Distribution delivery charges. Energy Charges for usage consumed between 9pm and 7am each day is credited back on your bill. The utility charges, including delivery charges for night time hours, are passed through at cost and aggregated on your bill. See Electricity Facts Label for details.
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.
Ross, something of a libertarian at heart, entered politics because he was ticked off that the municipal code prohibited him from paving the driveway to his historic home entirely in period-appropriate brick. (The code required some concrete.) He joined the city council in 2008 and was elected to his first term as mayor in 2014. He often likens the city to “Mayberry R.F.D.,” and it does have a town square with a courthouse, a coffee shop where you’re bound to run into people you know and a swimming hole. But it also has Southwestern University, and in 2010 university officials, following a student initiative, told the city council they wanted their electricity to come from renewable sources. The city had already set a goal of getting 30 percent of its power that way, but now, Ross and his colleagues saw their opportunity.
The blades for the wind generator are repurposed from a vehicle fan clutch. To attach the blades to the alternator, you can weld the fan clutch hub directly to the alternator hub — just make certain the fan is perfectly in line with the alternator shaft. Also, make sure the alternator’s built-in wire plug-ins are located on what will be the bottom of the generator. If you don’t have access to a welder, you can connect the fan clutch to the alternator using the following materials:
Wind turbines allow us to harness the power of the wind and turn it into energy. When the wind blows, the turbine's blades spin clockwise, capturing energy. This triggers the main shaft, connected to a gearbox within the nacelle, to spin. The gearbox sends that energy to the generator, converting it to electricity. Electricity then travels down the tower to a transformer, where voltage levels are adjusted to match with the grid.
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]
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]
The reliability of small wind turbines is (still) problematic. Even the good ones break much more frequently than we would like, and none will run for 20 years without the need to replace at least some part(s). Despite their apparent simplicity, a small wind turbine is nowhere near as reliable as the average car (and even cars will not run for 20 years without stuff breaking). If you are going to install a small wind turbine you should expect that it will break. The only questions are when and how often.
Artificial photosynthesis uses techniques including nanotechnology to store solar electromagnetic energy in chemical bonds by splitting water to produce hydrogen and then using carbon dioxide to make methanol.[182] Researchers in this field are striving to design molecular mimics of photosynthesis that utilize a wider region of the solar spectrum, employ catalytic systems made from abundant, inexpensive materials that are robust, readily repaired, non-toxic, stable in a variety of environmental conditions and perform more efficiently allowing a greater proportion of photon energy to end up in the storage compounds, i.e., carbohydrates (rather than building and sustaining living cells).[183] However, prominent research faces hurdles, Sun Catalytix a MIT spin-off stopped scaling up their prototype fuel-cell in 2012, because it offers few savings over other ways to make hydrogen from sunlight.[184]

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.”
Renewable energy resources 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 is resulting in significant energy security, climate change mitigation, and economic benefits.[8] The results of a recent review of the literature[9] concluded that as greenhouse gas (GHG) emitters begin to be held liable for damages resulting from GHG emissions resulting in climate change, a high value for liability mitigation would provide powerful incentives for deployment of renewable energy technologies. In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power.[10] At the national level, at least 30 nations around the world already have renewable energy contributing more than 20 percent of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond.[11] Some places and at least two countries, Iceland and Norway generate all their electricity using renewable energy already, and many other countries have the set a goal to reach 100% renewable energy in the future. For example, in Denmark the government decided to switch the total energy supply (electricity, mobility and heating/cooling) to 100% renewable energy by 2050.[12]
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]

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]

Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand, assuming all practical barriers needed were overcome. This would require wind turbines to be installed over large areas, particularly in areas of higher wind resources, such as offshore. As offshore wind speeds average ~90% greater than that of land, so offshore resources can contribute substantially more energy than land stationed turbines.[44] In 2014 global wind generation was 706 terawatt-hours or 3% of the worlds total electricity.[45]
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.

Okay, an “about solar” page wouldn’t be complete without a list of the largest solar power plants in the world, right? (Though, note that much of the solar power capacity in the world is in small installations and one of the prime advantages of solar is its decentralization and its ability to help “democratize” the electricity system — even the CIA and Department of Defense have focused on the national security benefits of solar.) Nonetheless, I think almost everyone loves a list of the “largest _________,” so here are two current lists (largest solar thermal power plants and largest solar photovoltaic power plants):

“As Trump’s Tariffs Raise the Cost of Solar Installations, Elon Musk and Tesla Cut Their Prices” • Tesla, unmoved by tariffs, is reducing prices on its solar systems 10–20% in recognition of the progress it has made streamlining its solar sales process by integrating Tesla Energy products into its existing high-traffic storefronts. [Red, Green, and Blue]
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.
Many industrialized nations have installed significant solar power capacity into their grids to supplement or provide an alternative to conventional energy sources while an increasing number of less developed nations have turned to solar to reduce dependence on expensive imported fuels (see solar power by country). Long distance transmission allows remote renewable energy resources to displace fossil fuel consumption. Solar power plants use one of two technologies: