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Wind and solar power are cheap, climate-friendly, and set to become mainstays of future energy supplies. But the energy generated varies greatly depending on the region. Which mix makes sense?
Modern wind turbines are more efficient and generate up to 20 times more electricity than they did 25 years ago. They are taller, larger and have longer blades. According to the investment bank Lazard, generating wind power from new plants costs 72% less today than in 2009.
That's made it one of the cheapest energy sources on the planet.
Electricity from windy regions on the coast now costs €0.04-0.05 ($0.05-0.06) per kilowatt hour (kWh), while in places with weaker wind it is €0.06-0.08, according to a study by the German-based research organization Fraunhofer Institute for Solar Energy Systems. For offshore plants in the sea, a kilowatt hour costs about €0.1 because they cost more to install and maintain.
By comparison, the price of photovoltaics have also fallen sharply — around 90% since 2009 — bringing electricity from a solar farm down to €0.02-0.06/kWh. But new power plants for other energy sources still cost more. A kilowatt hour of electricity from fossil gas costs around €0.11 cents, coal-fired electricity €0.16 and nuclear electricity €0.14-0.19.
Energy researchers assume that wind and solar power will become 20-50% cheaper by 2030 as the technology develops.
Experts say wind and solar energy could cover more than 95% of total global energy demand in the future. But depending on the region, different combinations make sense. This could include hydropower, batteries, electrolyzers to make hydrogen and synthetic fuels, as well as other storage and conversion technologies, said Christian Breyer, a solar economy professor from LUT University in Finland.
A study his team published in the journal Energy found it would be cheapest to generate about 76% percent of global energy demand with solar power and 20% with wind power. In regions with little sunshine, however, the share of wind power would be significantly higher: more than 90% in northern parts of Russia, 81% in the mid-west of the US, about 72% in northern China and about 50% in countries in central and northern Europe like Poland, the Netherlands, Great Britain and France. In Germany, the share of wind energy to cover the entire energy demand would be 31%.
In these regions, where the sun shines less brightly and winters can be grey, wind is often the cheaper alternative. "In Europe, wind power is therefore an absolutely central pillar of the energy supply," said Breyer. "If we don't have particularly good sunny days in Europe, we usually have very good windy days, so that goes well together."
Wind turbines today are up to 180 meters high and have blades as long as 80 meters. On land, just one such turbine has an output of up to 7200 kilowatts and can generate as much as 29 million kWh of electricity per year — enough to cover the private electricity needs of 16,000 people in Germany and 140,000 people in India.
Wind turbines are particularly powerful in the sea where wind blows with greater force and reliability. Offshore turbines have an output of up to 10,000 kilowatts, and are expected to reach 15,000 kilowatts in a few years time. A single turbine at a good location could satisfy the private electricity needs of some 40,000 people in Germany or for 370,000 in India.
But the complexities and cost of laying down power cables on the seabed and maintaining offshore wind farms means the electricity they generate is twice as expensive as that from turbines on land. Nonetheless, offshore wind farms in densely populated regions of the world could play a useful role in a climate-neutral energy supply.
About 7% of global electricity demand is now met by wind power. Last year, new turbines with a capacity of 93 gigawatts (GW) were installed, and the total installed line in 2020 was 743GW. Offshore turbines account for 34GW, with most located in the waters off the UK (10GW), China (8GW) and Germany (8GW). One of the world's first vast-scale offshore wind farms is the London Array off the Thames Estuary. Built in 2013, it has a capacity of 0.6GW from 175 turbines, and cost the equivalent of €2.5 billion. It satisfies the private electricity needs of 1.7 million Britons.
Up to now, offshore wind farms have mainly existed in shallow waters with a water depth of up to 50 meters. The turbines stand on a foundation in the seabed. But many coastal waters in the world are much deeper, making wind farms with foundations unfeasible.
For this reason, floating wind turbines are now also mounted on pontoons in harbors, then pulled into the sea and fixed to the seabed with long chains. The world's first floating turbines were installed off the Scottish coast in 2017, and later off the coasts of Japan, France and Portugal. Today, all these turbines together have a total capacity of 0.1GW. The Global Offshore Wind Report expects an installed capacity of 6.3GW by 2030.
However, the strongest growth will continue to come from onshore wind turbines. According to the LUT study, for a climate-neutral energy supply — which includes not only energy for electricity but also for transport, heating and industry — the globally installed wind power capacity would have to increase tenfold to around 8039GW and quadruple to 244GW in Germany.
Wind power is particularly cheap at windy locations. But if this electricity then has to be transported many hundreds of kilometers, the costs rise and can even double the price for the buyer. This is why transporting electricity long distances is often not worthwhile.
Still, generating electricity in remote regions can make sense if it is used directly for the production of so-called e-fuels. These are synthetic fuels that are to replace petroleum products such as paraffin, diesel and petrol in the future and special basic materials for the chemical industry.
They are produced by electrolysis from electricity, water, CO2 and nitrogen from the air. The fuels can then be transported in tankers, pipelines or trains. The first commercial plant for production is currently being built in the south of Chile.
In a joint project there, companies like carmaker Porsche and Siemens Energy want to use the strong wind to generate cheap electricity to produce e-fuels, expecting around 550 million liters per year from 2026.
"With the project in Patagonia, you can see now what the global standard will be," said Breyer. "In ten years, we'll see dozens of projects like this a year springing up like mushrooms."
Translated from German by Ajit Niranjan