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Rising Renewables

Renewable energies, such as solar, wind and hydropower, may be the best way to reduce global carbon emissions. Or are they? Read more.

On the 7th June 2017, renewables – for the first time ever – briefly generated more than 50% of the UK’s electricity. This is nothing new for some countries, with Paraguay, Iceland and Norway producing more than 98% of electricity with renewables. So are they the future?

Introducing the debate

There are a vast array of renewable energy sources – hydropower, wind energy, solar energy and biofuels to name a few. They’re decreasing in cost and increasing in popularity, but not every country is able to exploit their full potential. Some, such as Brazil, are able to capitalize on their natural resources very well, while others don’t have such luck. For some renewable technologies, their use remains controversial and ‘green status’ somewhat questionable.


River damming is the reason why some countries are able to generate close to 100% of their electricity capacity with renewables. A single hydropower plant can generate more electricity than 1000 wind turbines. With the exception of the energy used to build the dam and power station, the technology is free of greenhouse gas emissions. But, the land required to produce a reservoir big enough can be hundreds, if not thousands of square kilometers. In Brazil, the Belo Monte dam will flood virgin Amazonian forest. In China, the Three Gorges Dam resulted in the displacement of a million people. Flooded vegetation and soil at the bottom of the reservoir can decompose to release methane gas – each molecule of which traps 25 times more heat energy than carbon dioxide.


The decreasing cost of solar panels means that it is becoming an increasingly viable alternative to fossil fuels. The panels are becoming more efficient and sophisticated, with tracking mechanisms to follow the sun to improve their output. Solar farms can be built on less productive land, such as Solar Star farm – built in the Californian desert. But when there’s no sun, they stop working. At night, when electricity demand can peak, solar power cannot help – unless it has been stored from the day using batteries or some other form of storage technology (e.g. pumping water uphill which is later released to generate hydropower). For private homeowners looking to put solar panels on their roofs, the upfront cost can be very high – although in the long-run there’s a big financial saving.


Wind farms are also becoming more popular as the price of the turbines decreases. Growth is largely in off-shore wind farms, partly because of a strong NIMBY (Not In My Back Yard!) reaction to onshore wind farms. Wind turbines produce electricity whenever sufficient wind is blowing, unlike solar, but are unable to respond to peaks in demand or at times of low wind. Onshore wind farms typically make good use of land and offshore wind farms can also often be situated close to large cities, thus reducing the cost and inefficiency of transmission. The London Array is the largest offshore wind farm in the world and is under 100km from London. However, expansion was stopped due to the impact on migratory birds that can be killed by the turbines.

© University of Exeter
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