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Professor Magda Titirici, Chair in Sustainable Energy Materials at Imperial College London, offers an introduction to renewable energy and the future of clean, green power in the UK.
Renewable energy comes from sources that replenish naturally and continually within a human lifetime. Renewable energy is often called sustainable energy.
Major sources of renewable energy include solar, wind, hydroelectric, tidal, geothermal and biomass energy, which is derived from burning plant or animal matter and waste.
Switching our reliance on fossil fuels to renewable energy sources that produce lower or no greenhouse gas emissions is critically important in tackling the climate crisis.
Clean energy doesn't produce any pollution once installed. Nor does green energy, which comes from natural sources such as the Sun and is produced without any major negative impacts on the environment. Renewable energy refers to sources that are constantly replenished.
While there is often overlap between these definitions and most renewable energy sources can also be considered clean and green, it's not always the case.
Nuclear energy doesn't release greenhouse gases into the atmosphere, so some people consider it to be clean - providing the radioactive waste is stored safely and doesn't escape into the environment. But the uranium energy source used in nuclear power plants isn't renewable.
Non-renewable energy comes from natural resources such as coal, oil and natural gas that take billions of years to form, which is why we call them fossil fuels. They are present in finite amounts and will run out, as we are using them far more quickly than they form.
Research based on 2015 data predicts that coal stocks will last well into the next century, but oil and natural gas reserves (stocks that we know we can extract from) will run out in the late 2060s. However, scientific models suggest that if we are to limit global warming to 2°C - the target agreed at COP26 is 1.5°C - over 80% of coal, 50% of gas and 30% of oil reserves will need to be left untouched anyway.
When we extract fossil fuels from deep within the planet and burn them, we can generate electricity quite efficiently. But the process releases a lot of carbon dioxide (CO2) into the atmosphere, which contributes to the greenhouse effect, global warming and biodiversity loss.
Magda explains, 'Fossil fuels brought with them immense technological progress but using them releases CO2 into the atmosphere, which acts like a blanket, trapping heat that would otherwise escape into space and causing global warming.'
The energy sector is responsible for almost three-quarters of the emissions that have caused global temperatures to warm by 1.1°C since pre-industrial times.
If we continue to use fossil fuels, the effect will only worsen.
Magda adds, 'If we want to live on this planet much longer than 2050 and keep temperature levels below the 1.5°C of warming agreed to by governments around the world, we need to make some radical changes right now. We need to move to technologies that will give us the same level and comfort of living but drastically cut our emissions and carbon footprint.'
The main types of renewable energy are wind, solar, hydroelectric, tidal, geothermal and biomass. Read on to discover the pros and cons of each of these renewable energy sources.
One of the main benefits of most renewable energy sources is that they don't release carbon dioxide or pollute the air when they are used to produce electricity or heat. Greenhouse gases are emitted during the lifetime of some of the technologies - for example, during their manufacture or construction - but overall emissions are significantly lower than for fossil fuels.
Whereas some countries lack direct access to fossil fuels and must rely on international sources, renewable energy often allows countries to supply their own energy needs, a big economic and political advantage.
In 2020, 42% of the UK's electricity came from renewable energy. A quarter of the UK's electricity was produced by wind power, which is the highest proportion of any G20 country and more than four times the global average. Statistics on UK energy trends reveal that from April to June 2022, nearly 39% of the UK's electricity came from renewable energy, slightly more than during the same period in 2021, but down from 45.5% between January and March 2022 when it was unusually sunny and wind speeds were high.
'There has been good news in recent years in terms of progress on renewables,' says Magda, 'but in my opinion, the UK is still lagging behind. It is not so strong yet for truly sustainable technologies. It needs storage and conversion.'
Magda believes that wind (particularly offshore), solar, green hydrogen and rapid innovation in battery storage will be key to the UK reaching net zero by 2050.
She explains, 'The UK is a really windy place, so wind is the perfect renewable energy technology. By 2035 wind and solar should provide 75-90% of total UK electricity to bring emissions down significantly.'
'It has already been shown that it's feasible to produce 90% of the UK's electricity from wind and solar combined. The tech is there and it's becoming more efficient and affordable each year.'
'Offshore wind capacity will also help produce green hydrogen, another crucial part of the UK decarbonisation path.'
Green hydrogen is a fuel created using renewable energy in a process known as electrolysis. When green hydrogen is burned to produce energy, it releases water.
It's predicted that the UK will need 100 terawatt-hours of green hydrogen by 2035.
A terawatt-hour is a unit of measurement that's large enough to describe the annual electricity needs of entire countries. For scale, one terawatt-hour is equivalent to burning 588,441 barrels of oil.
Magda believes the UK is at a very critical point in its sustainable technologies journey.
'Everything will depend on what happens this year and next. We need to see radical changes, investment, subsidies and support to reach our target of net zero by 2050.'
'It would cost less than 1% of GDP to get to net zero by 2050 but the advantages would be immense: new jobs, a sustainable economy and a healthy and resilient society.'
One of the biggest challenges the UK is facing right now is battery storage and access to materials like cobalt and lithium, which are needed to produce lithium-ion batteries at scale.
Batteries help make renewable energy supply reliable and portable - such as in the case of electric vehicles.
Batteries are an important part of our transition to renewable technologies, as they allow energy to be stored and released as needed. For example, solar panels generate energy during the day, and batteries make it possible to store and use that electricity at night.
Currently, just a few countries are responsible for most of the world's production of lithium.
According to Magda, the UK lacks access to the supply chain needed for Li-ion batteries. 'As a result, she adds, 'Johnson Matthey, which is a major company driving battery innovations in the UK, announced they would stop lithium battery research because they are unable to secure a path to raw materials and be competitive on the international market.'
Museum researchers are investigating whether it would be possible to develop a more sustainable, domestic supply chain by extracting lithium from UK rocks. They made a key breakthrough in 2021 when they produced battery-grade lithium chemicals from UK rocks for the first time.
According to Professor Richard Herrington, Head of Earth Sciences at the Museum, 'An increased, reliable supply of lithium is critical if we are to meet the rising demand for electric cars and provide a dependable supply of energy from renewable sources. The next generation of batteries that don't require lithium may still be three to five years away from being ready for public use.'
However, Magda is optimistic that the UK could lead in emerging battery technologies. 'I think the UK has an amazing opportunity to pioneer the next generation of batteries,' she says.
Innovative models already under development at The Faraday Institution include:
Magda adds, 'We need to focus on the areas where the UK has the potential to lead. The UK has such a big tradition in new materials and discoveries, we could move to completely new technologies both for batteries and hydrogen production.'
'There are a lot of challenges, but if we're investing in it, we could be future leaders and even solve one of the most difficult challenges in decarbonisation: flight.'