99 Fun Facts About Renewable Energy

Which physical effect lets a solar cell turn sunlight directly into an electric current, with no moving parts?

The photovoltaic effect frees electrons that stay inside the semiconductor and flow as current; in its close cousin, the photoelectric effect that won Einstein his Nobel Prize, light knocks them right out of the material.

Which country held the largest installed wind power capacity globally at the end of 2024?

China ended 2024 with more than three times the wind capacity of the second-placed United States, yet as late as 2009 the US still led the world.

Which folk singer did the US government hire in 1941 to write songs celebrating the Columbia River's new hydroelectric dams?

Woody Guthrie spent one month on the federal payroll and wrote 26 songs for a documentary about the dams, among them 'Roll On, Columbia'.

Which geothermal plant technology uses a low-boiling secondary fluid to turn a turbine?

Binary cycle plants pass the geothermal water through a heat exchanger, so it never touches the turbine and goes straight back underground; that lets them run on reservoirs too cool to drive a steam plant.

What process lets sealed tanks on farms turn manure and food waste into methane-rich biogas?

Anaerobic digestion is microbes breaking down organic matter without oxygen; the biogas they give off is mostly methane and carbon dioxide and can be burned for heat and power much like natural gas.

What force creates the ocean tides that tidal power stations harness?

The gravity of the Moon and Sun pulls on the oceans to raise tides; at new and full moon the two pulls line up, producing the largest spring tides roughly twice a month.

What solar technology uses mirrors to focus sunlight on a receiver, heating fluid to make steam for a turbine?

Concentrated Solar Power (CSP) makes heat before it makes electricity, and that heat can be banked in tanks of molten salt, so a plant can keep its turbine spinning after sunset.

What is a key advantage of siting turbines offshore rather than on land?

Stronger, steadier winds blow over open water, giving a higher capacity factor; offshore speeds also tend to peak in the afternoon and evening, when electricity demand is highest.

Which of these is a documented environmental impact of building a large dam and reservoir?

Blocked fish migration routes are a classic dam impact: salmon and other migratory fish cannot pass the wall without ladders. Dams also trap sediment that would otherwise build deltas downstream.

Enhanced Geothermal Systems extract heat from rock that conventional plants cannot use because it lacks what?

Hot dry rock lacks the natural water and permeability a conventional plant needs, so Enhanced Geothermal Systems pump high-pressure water down an injection well to shear open cracks and create an artificial reservoir.

Which crop supplies nearly all of the fuel ethanol made in the United States?

Corn starch is broken down into sugars and fermented into ethanol, which is then blended into nearly all US gasoline, most commonly at 10% as E10.

What billing mechanism credits solar-panel owners for excess power sent back to the grid?

Net metering sets a home's surplus solar power against what it draws after dark; in its simplest form the electric meter just runs backwards while the panels are exporting.

Green hydrogen is made by which process, which splits water using wind or solar power?

Electrolysis runs an electric current through water to split it into hydrogen and oxygen; yet most hydrogen is still made from natural gas, and as of 2024 the low-emission kinds were under 1% of world output.

Which type of silicon solar panel is known for its high efficiency and a uniform, dark appearance?

Monocrystalline panels get their uniform dark look because each cell is cut from a single high-purity silicon crystal, which is also what gives them their high efficiency.

What component atop a wind turbine tower houses the gearbox, generator and control systems?

The nacelle sits atop the tower and swivels on a yaw drive to keep the rotor facing the wind; its name is French for a small boat.

Which of these uses geothermal energy directly, rather than electricity generated from it?

Heating greenhouses takes water of only about 25 to 90 °C, far cooler than a power plant needs, so growers can tap wells that could never drive a turbine.

What chemical process is most commonly used to produce biodiesel from vegetable oils or animal fats?

Transesterification reacts the oil with an alcohol such as methanol and a catalyst, yielding biodiesel plus glycerin, a syrupy co-product sold on to makers of cosmetics and medicines.

Which technology held the vast majority of the world's grid energy storage capacity as of 2020?

Pumped-storage hydro pumps water uphill when power is cheap and lets it run back down through turbines at peak demand, working like a giant rechargeable battery.

When a company buys a carbon offset to cover its own greenhouse gas emissions, what is it paying for?

Funding reductions elsewhere, such as a wind farm or a forest project, only counts if the cut would not have happened without the buyer's money, a test known as additionality.

Which type of hydroelectric plant diverts part of a waterway's flow through a penstock with little or no storage?

A run-of-river plant has little or no reservoir, so its output rises and falls with the river's natural flow; any small pond it does keep is called pondage.

Second-generation biofuels are primarily derived from which category of feedstocks?

Second-generation biofuels come from non-food biomass and crop residues such as straw, wood waste and energy grasses grown on marginal land, sidestepping the worry that fuel crops take food off the table.

What name is given to an electricity network that uses two-way digital communication to integrate renewables and respond to faults?

A smart grid carries data as well as power in both directions, so utilities can restore service faster after an outage and households can see their own use and shift it to cheaper hours.

Unlike solar and wind, reservoir hydro is prized by grid operators for being what?

Reservoir hydro is dispatchable on demand: operators can open the gates within minutes when power is needed, while solar and wind follow the weather, which is why they are paired with storage.

In which country did James Blyth build the first electricity-generating wind turbine in 1887?

Scotland: Blyth's cloth-sailed windmill charged batteries that lit his holiday cottage at Marykirk from July 1887; the American Charles Brush, often given the credit, only started his machine that winter.

Why can no wind turbine capture all of the wind's energy?

Air must keep flowing: a rotor that took all of the wind's energy would stop the air dead and block the wind behind it, so the best possible catch is about 59%, a ceiling known as the Betz limit.

Solar cells found their first major job in the late 1950s powering which machines?

Space satellites were the first big customers: Vanguard 1 flew with solar cells in 1958, and within a few years they were powering most spacecraft in orbit, long before they were cheap enough for rooftops.

In which country did a prince light a few bulbs with the world's first geothermal generator in 1904?

Italy: Prince Piero Ginori Conti ran his small generator on natural steam rising from the ground at Larderello in Tuscany, a field that has supplied geothermal power for more than a century.

Which US geothermal field hosts the largest group of geothermal power plants in the world?

The Geysers has made power from natural steam since 1960; when its pressure began to fall, operators started piping in treated wastewater from nearby towns to recharge the field.

Which Columbia River dam overtook Hoover Dam as the world's largest hydroelectric station in the 1940s?

Grand Coulee's irrigation role had to wait: once war came, its power went first to the plants building planes and ships.

The low-head Kaplan hydro turbine is named after an engineer from which country?

Austria: Viktor Kaplan, born in Styria, taught in Brno; his propeller turbine's blades swivel to suit the flow, so it stays efficient on big, slow rivers where the drop is small.

The Three Gorges Dam, the world's largest power station by capacity, spans which river?

The Yangtze's Three Gorges Dam can generate 22,500 MW, but filling its reservoir meant moving whole towns and villages: more than a million people had to be resettled.

The 14 GW Itaipu Dam sits on the Paraná River along Brazil's border with which country?

Half its 20 generators run at 50 Hz for Paraguay and half at 60 Hz for Brazil, and most of the Paraguayan share is exported back across the border.

The Sihwa Lake station, the world's largest tidal power plant at 254 MW, is in which country?

South Korea built the plant into a seawall that had turned Sihwa Lake into a stagnant, polluted reservoir after 1994; letting the tide flow through turbines was meant to clean the lake as well as make power.

The world's first tidal power station opened in 1966 on the Rance estuary, in which region of France?

Brittany's Rance estuary was chosen for its huge tides, which average about 8 metres between low and high water; its 240 MW barrage stayed the largest tidal plant in the world for 45 years.

Bhadla Solar Park, a 2,200 MW Indian solar plant, lies in which desert?

Bhadla lies in the Thar Desert of western Rajasthan, where searing heat, poor soil and frequent dust storms make the land hard to live on, but open space and constant sunshine make it ideal for solar panels.

Which energy company developed Hornsea 2, the world's largest offshore wind farm when it opened in 2022?

Ørsted developed Hornsea 2 off the Yorkshire coast; until 2017 it was DONG Energy, an oil and gas producer, which sold off its fossil business and took a new name.

The first practical silicon solar cell was publicly demonstrated in 1954 at which laboratory?

At Bell Laboratories, Daryl Chapin, Calvin Fuller and Gerald Pearson unveiled a silicon cell several times better than the selenium cells of the 1880s, which had turned only about 1% of sunlight into power.

Which solar cells stack two absorbing layers to beat a single layer's efficiency ceiling?

Tandem cells stack materials tuned to different colours of sunlight, so less of the light's energy is lost; a single layer tops out near 33%, a ceiling known as the Shockley–Queisser limit.

IRENA, the intergovernmental renewable energy agency founded in 2009, is headquartered in which oil-rich Gulf city?

Abu Dhabi hosts IRENA in Masdar City, its planned low-carbon district; Germany, where the agency was founded in 2009, received its innovation and technology centre in Bonn instead.

Which oil company, then called Statoil, built the world's first commercial floating wind farm in 2017?

Equinor drew on decades of offshore oil work for its Hywind project: the five turbines stand on floating spar cylinders, each held by three anchors, in water about 100 metres deep off Peterhead.

Which Australian state is home to the Hornsdale Power Reserve, the world's largest lithium-ion battery when it opened in 2017?

South Australia ordered the battery after a 2016 blackout hit the whole state; Elon Musk bet it would be built within 100 days of signing or be free, and Tesla finished in about 60.

Ivanpah, the world's largest solar thermal plant in 2014, stands in which desert near Las Vegas?

Mojave: Ivanpah's mirrors focus sunlight on boilers atop three towers, yet the plant burns natural gas each morning to get its steam going.

The Noor Ouarzazate solar complex is in which country?

Morocco's Noor Ouarzazate complex, switched on in stages from 2016, stores the heat from its mirror fields in molten salt, so it can go on producing electricity into the night.

Which capital city heats nearly all its buildings with geothermal water?

Reykjavík pipes hot water from nearby geothermal fields into nearly every building, then runs it, cooled, under streets and pavements to keep them free of ice.

The Olkaria geothermal plants beside Lake Naivasha in the Great Rift Valley supply power to which country?

Kenya's Olkaria plants stand inside Hell's Gate National Park, sharing it with zebras and buffalo; they have made the country Africa's leading producer of geothermal power.

On a gusty night in July 2015, which country's wind turbines generated 140% of its electricity demand?

Denmark's turbines covered 116% of demand that evening and 140% by 3 a.m., and the surplus flowed down cables to Germany, Norway and Sweden.

Brazil's decades-old ethanol fuel programme is built on which crop?

Sugarcane: Brazil launched its Pró-Álcool programme in 1975, and most of its cars can now run on pure ethanol or any petrol blend; the leftover cane fibre, bagasse, is burned to power the sugar mills.

Germany's Renewable Energy Sources Act of 2000 guaranteed green-power producers a fixed price for 20 years through which mechanism?

The feed-in tariff was paid for by a surcharge on every electricity bill; from 2017 the law switched most new projects to competitive auctions instead.

The 'duck curve' of solar-heavy grids was named by the grid operator of which US state?

California's grid operator, CAISO, named the duck curve: net demand sags at midday when solar floods the grid, then climbs steeply at sunset, a shape that batteries charged at noon help flatten.

Which US president had 32 solar water-heating panels installed on the White House roof in 1979?

Jimmy Carter predicted the panels could end up a museum piece, and one did: after they came down during roof repairs in 1986, a panel went to the National Museum of American History.

Which farm animals are most often hired to graze under solar panels in place of lawnmowers?

Sheep are the usual choice because they fit among standard solar arrays with no changes to the equipment, and they get forage and shade in return for trimming the grass.

CopenHill, a Copenhagen power plant that burns city waste, has which leisure facility on its roof?

A ski slope open all year runs down CopenHill's 85-meter-tall sloping roof, and the plant also carries a hiking trail and one of the world's tallest climbing walls.

NASA's Juno probe was built with three giant solar panel wings to power its orbit around which planet?

Jupiter gets only about 4% of the sunlight Earth does, yet Juno was built to run on solar panels where every earlier probe to the outer planets carried a plutonium power source.

Which lightweight wood, a favorite for model airplanes, forms the core of many wind turbine blades?

Balsa is light but stiff for its weight, and most of the world's harvest, grown largely in Ecuador, ends up as structural cores inside wind turbine blades.

NASA's solar-powered Opportunity rover fell silent in 2018 after which Martian event dimmed the Sun?

A dust storm that wrapped around the whole planet ended a mission planned to last about 90 Martian days that had instead kept going for more than 5,000.

Whose alternating-current patents shaped the 1895 Adams hydroelectric plant at Niagara Falls?

Nikola Tesla's patents helped make the Adams plant the world's first large-scale alternating-current power station, and a statue of the inventor stands on Goat Island beside the falls.

The 19 windmills of Kinderdijk, a UNESCO site, were built to drain farmland in which country?

The Netherlands built the Kinderdijk mills around 1740 to lift water in stages, first into a holding basin and then into the river whenever its level fell low enough.

In the Northern Hemisphere, fixed solar panels are usually angled to face which direction?

South is where the midday Sun sits for anyone north of the tropics, so panels tilted that way collect light all day; below the equator the rule flips and they face north.

The Atacama, the driest non-polar desert and a hotspot for solar farms, lies mainly in which country?

Chile's Atacama gets some of the strongest sunlight on Earth, and its Cerro Dominador solar tower can keep generating for up to 17.5 hours with no direct sunshine.

The energy in firewood and farm waste was first captured from sunlight by which process in plants?

Photosynthesis lets plants soak up almost as much carbon dioxide while growing as they give off when burned, which is why biomass is often counted as carbon-neutral.

Biogas from landfills and manure tanks is mostly which flammable gas, a potent climate warmer if leaked?

Methane traps far more heat than carbon dioxide, so piping it from rotting waste to a generator both makes electricity and keeps it out of the air.

The sunlight that drives solar panels, winds and rainfall is made in the Sun's core by which process?

Nuclear fusion in the core turns hydrogen into helium, and the light it releases also heats Earth unevenly, which is what sets the winds blowing.

The Philippines owes its rich geothermal power to lying along which feature of the Pacific?

The Ring of Fire holds around two-thirds of the world's volcanoes, and the same underground heat lets the Philippines run power stations on steam from the ground.

Geothermal power plants tap underground water heated by which liquid rock that has not yet erupted?

Magma becomes lava only once it erupts, and geothermal drilling crews have struck it directly on a few occasions, including twice in Iceland.

Hoover Dam, whose hydroelectric turbines sit on the Nevada–Arizona border, holds back which river?

Colorado River water piles up behind the dam as Lake Mead, and from 1933 to 1947 the structure itself was officially called Boulder Dam.

Solar cells rely on light freeing electrons, an idea that earned which physicist the 1921 Nobel Prize?

Albert Einstein won it not for relativity but for his 1905 argument that light arrives in packets of energy, later named photons.

Under which president was the Tennessee Valley Authority set up in 1933 to build hydroelectric dams?

Franklin Roosevelt's TVA broke ground on its first hydroelectric dam within months, in a valley where malaria was then widespread.

Which home appliance, often linked to buried pipes, draws on the steady temperature of the ground?

A heat pump only moves warmth instead of making it, so it can deliver three to five times more heat energy than the electricity it uses.

America's earliest solar water heaters, used before 1900, were rooftop tanks painted which color?

Black surfaces absorb the most sunlight, and the idea has barely changed: modern collectors pass water beneath a dark absorber plate sealed under glass.

Roscoe and Horse Hollow, each the world's largest wind farm when built, stand in which oil-rich state?

Texas landowners share in the earnings: Roscoe alone, organized with help from a local cotton farmer, pays royalties to as many as 400 of them.

Nuclear power is not counted as renewable because its fuel is made from which mined metal?

Uranium is found throughout Earth's crust, but supplies are limited to what can be mined, and that limit is what separates it from sunshine, wind and flowing water.

Which oil-dependent US state passed a 2015 law requiring all its electricity to be renewable by 2045?

Hawaii made the pledge while burning shipped-in petroleum for most of its electricity, a far heavier reliance on oil than any other state.

Water held high behind a hydroelectric dam stores which form of energy, released as it falls?

Potential energy grows with height, so the power a dam can extract depends on both the volume of water and how far it drops, a distance engineers call the head.

Which Nordic oil exporter generates about 90% of its own electricity from hydroelectric dams?

Norway trades its hydropower with flatter neighbors such as Sweden and Denmark, which lean far more on wind power.

Which instrument, typically three or four spinning cups on a mast, measures wind speed at turbine sites?

The anemometer was first described around 1450 by the Italian architect Leon Battista Alberti, four centuries before the spinning-cup design appeared.

Which device turns direct current from solar panels into the alternating current used in homes?

An inverter is needed because panels put out direct current, and some rooftop systems fit a tiny one, called a microinverter, to every single panel.

The earliest known windmills, turning around an upright shaft, appeared by the 9th century in which land?

Persia had these horizontal mills some three centuries before the familiar vertical windmill first appeared in northwestern Europe in the 12th century.

The curved blades of a Darrieus wind turbine, which spins on an upright mast, resemble which kitchen tool?

Egg beater is the usual nickname for the bowed shape, which a French aeronautical engineer patented in the 1920s so that the blades could support themselves.

Legend says Archimedes used mirrors to focus sunlight and burn Roman ships attacking which Sicilian city?

Syracuse's supposed heat ray was tested by MIT students in 2005 and again on MythBusters, which called the legend busted because setting a ship alight took too long.

Which word, familiar to pilots, describes turning a wind turbine's rotor to face the wind as it shifts?

Yaw motors follow a wind vane to keep the rotor square to the breeze, while pitch means twisting each blade to control the rotor's speed.

Spain's Gemasolar solar tower once ran for 36 days straight by storing heat overnight in which liquid?

Molten salt holds enough heat for Gemasolar to generate for 15 hours without sunlight, which made it the first commercial tower plant able to run through the night.

Egypt's Aswan High Dam, a major hydroelectric station on the Nile, created which vast reservoir?

Lake Nasser threatened to drown the Abu Simbel temples, so they were moved to higher ground on its shores in a UNESCO rescue campaign.

Which country paid for its Grand Renaissance Dam on the Blue Nile largely with bonds and public donations?

Ethiopia raised most of the money at home because international lenders largely stayed away, a gap long blamed on Egypt's campaign to keep control of the river's water.

North America's only tidal power station ran until 2019 in which bay, known for the world's highest tides?

The Bay of Fundy station at Annapolis Royal could generate only while the tide was going out, for about five hours twice a day.

Three Pelamis machines, floating tubes named after a sea snake, formed a 2008 wave farm off which country?

Portugal's Aguçadoura project was the world's first wave farm with more than one machine, yet it was shut down just two months after its official opening.

At the 1900 Paris world's fair, a diesel engine ran smoothly on oil pressed from what?

Peanuts supplied the fuel at the French government's request, and the engine ran so smoothly that few visitors realized it was not burning petroleum.

Drax, a giant Yorkshire power station, converted its boilers to burn mainly which fuel from North America?

Wood pellets for Drax came mostly from across the Atlantic, and in 2014 the plant alone took about 60% of all the wood pellets the United States exported.

Which organisms, grown in open ponds or sealed tanks, can yield far more fuel oil per acre than oil palms?

Algae can produce an estimated 10 to 23 times as much oil per hectare as oil palm, yet a long US research program found the fuel could not compete with petroleum on cost.

Wind and hydro generators descend from an 1831 spinning metal disk built by which British scientist?

Michael Faraday's disk showed that moving a conductor through a magnetic field makes electricity flow, the principle every turbine-driven generator relies on.

A large share of Earth's inner heat, the source of geothermal power, comes from which ongoing process?

Radioactive decay of minerals keeps replacing much of the heat that leaks out through the crust, which is why geothermal power is counted as renewable.

Which Icelandic spa is filled with water already used by the Svartsengi geothermal power station?

The Blue Lagoon began as pools of runoff that formed soon after the plant opened in 1976, and silica in the water gives it a milky color.

Wairakei, a pioneering geothermal power station from 1958, lies in the Taupō Volcanic Zone of which country?

New Zealand built Wairakei among hot pools and boiling mud, and it was the first power station in the world to run on wet steam.

Which Vermont city, once led by Mayor Bernie Sanders, switched entirely to renewable electricity in 2014?

Burlington got there with a mix led by hydro dams, a timber-burning plant and wind farms, plus only a sliver of solar power.

In 1888 inventor Charles Brush built a giant wind turbine to power his mansion in which Ohio city?

Cleveland's Euclid Avenue hosted the world's first automatically operated wind turbine generator, which Brush used to charge the 12 batteries in his home.

Which rare-earth metal goes into the powerful permanent magnets used in some wind turbine generators?

Neodymium magnets, developed in 1984 by General Motors and Sumitomo, are the strongest permanent magnets sold, though most wind turbines get by without them.

Which Pacific territory of three atolls swapped its diesel generators for solar panels in 2012?

Tokelau had electricity for only about 16 hours a day under diesel; its 4,032 panels and 1,344 batteries were built to cover all of its demand.

Which inventor, nicknamed the Sun Queen, designed the heating for the 1948 Dover Sun House?

Mária Telkes built the house with architect Eleanor Raymond and money from sculptor Amelia Peabody, storing each day's solar warmth to heat the rooms later.

Which Swiss aircraft, piloted by Bertrand Piccard and André Borschberg, circled the globe on sunlight alone?

Solar Impulse 2 needed 506 days to finish the journey in 2016, including a long halt while a battery cooling system was installed.

Lake Kariba, the largest artificial reservoir by volume, sits behind a dam on which African river?

The Zambezi filled the lake between 1958 and 1963, creating a reservoir four times the size of the one behind the Three Gorges Dam.