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What is renewable energy?

Discover all you need to know about renewable energy, including the advantages and disadvantages of using renewable energy rather than fossil fuels.

Renewable energy header

Renewable energy has been on the rise for over a decade, and many agree that it is an important part of combating climate change. The hope is that, eventually, clean energy will replace fossil fuels, which cause so much damage to the environment and living creatures. For now, though, we’re still seeing exciting growth in the renewables industry.

You may already know a bit about renewable energy, but we’re here to give you the complete lowdown. We’ll be discussing fossil fuels, types of renewable energy, pros and cons of renewable energy, how renewable energy is being used around the world and what the future of renewables could hold.

What are fossil fuels?

The three main types of fossil fuels are coal, crude oil and natural gas. They’re named fossil fuels because they were formed from the fossils of plants and animals from millions of years ago, and their origins are also the reason why they have a high carbon content. To learn more about the history of fossil fuels, try our Global Resource Politics: the Past, Present and Future of Oil, Gas and Shale course.

Fossil fuels are extracted using a range of methods, including mining, drilling, fracking and acidizing. All of these methods are harmful to the environment, whether through destroying ecosystems and landscapes, causing deadly oil spills, increasing air and water pollution and creating greenhouse gases that heat the earth. The planet’s rising temperature is one of the better-known symptoms of climate change and has already resulted in dangerous heatwaves and melting polar ice caps. 

According to BP’s Statistical Review of World Energy 2020, crude oil currently creates the largest percentage of the world’s energy, at 33%. Coal-fired power plants currently fuel 27% of global electricity, and natural gas makes up 24% of global energy consumption. 

These stats show that fossil fuels are still supplying 84% of the world’s energy. The reason for the continued use of fossil fuels when we have alternative energy sources is because we’ve relied heavily on them for about 150 years. They’re relatively efficient, ready-made and well-established. However, with renewable energy on the rise, we hope our reliance on fossil fuels will come to an end. To find out more about carbon emissions, check out our blog on how to reduce your carbon footprint

What is renewable energy?

Renewable energy comes from energy sources that replenish themselves, and is, therefore, naturally sustainable. For example, sunlight and wind are not powered by anything other than nature, and so we can always rely on them to create energy – so long as the weather permits it. 

Another term that gets thrown around a lot when referring to renewable energy is ‘clean energy’ because it doesn’t require any ‘dirty’ methods or have consequences that will harm the environment.

If you’re wondering what we mean by ‘energy’ in the first place, this can refer to several things. Generally, scientists define energy as the ability to do work, but it can take the form of heat, electricity, fuel, chemical reactions and more. There are two types of energy, kinetic and potential. Kinetic energy is energy in motion and potential energy is stored energy.

Although renewable energy might sound like something fairly recent, humans have actually been harnessing the power of mother nature for centuries. Waterwheels powered machinery as far back as 200 BC, windmills pumped water and milled grain in the 1500s, and the world’s first solar energy system was created in the 1860s. 

The first instance of renewable energy being used commercially was in 1927 when some US farmers bought wind turbines. We’ve come a long way since then, and now have entire renewable energy plants and farms to help power our planet in a kinder way and create a sustainable bioeconomy

What are the pros and cons of renewable energy?

There are pros and cons to everything in life, and although renewable energy has more advantages, there are reasons why fossil fuels are still the number one energy provider. Here, we’ll provide you with an overview of the advantages and disadvantages. 

Advantages of renewable energy

  • It’s much better for the environment. Using renewable energy instead of fossil fuels helps to protect the lives of animals and plants and reduces the consequences of climate change.

  • We have infinite resources. We’ll never run out of sunlight, wind, ocean or organic matter.

  • We don’t have to rely on certain countries. Some countries produce a lot of fossil fuels, whereas others don’t have the materials or resources. Using renewable energy reduces the reliance of countries without naturally occurring fossil fuels on other countries for exports. Additionally, using alternative energy sources alleviates pressure on certain countries to extract high amounts of fossil fuels.

  • New jobs are always being created in this growing sector. Irena’s annual review of renewable energy and jobs found that jobs in the sector reached 11.5 million globally in 2019. Interestingly, they also found that there were better rates of inclusion and gender balance within renewables jobs compared to the fossil fuels market.

  • Maintenance costs are lower. Renewable energy equipment such as a wind turbine doesn’t have that many moving parts, making maintenance quite simple and inexpensive. Also, since the equipment doesn’t require the use of any flammable or combustible materials, it doesn’t need repairing often. This can save a lot of money in the long run.

Disadvantages of renewable energy

  • It cannot be stored. For now, we cannot store large amounts of sunshine or wind power, so energy production is reliant on certain weather conditions to function. This means that renewable energy can be intermittent, but this is why it’s good to have multiple different types of renewable energy production. This could change in the future, however, as Lancaster University recently discovered a crystalline material that may be able to store solar energy for months.

  • It can be more expensive than fossil fuels upfront. Despite lower maintenance costs and the ability for renewable energy production to save money and energy in the long run, the upfront costs for the technology can be more expensive than for fossil fuels. This means that investors and companies might sometimes choose fossil fuels, incorrectly thinking that they are cheaper overall.

  • There are geographic limitations. Certain environments make it more difficult to use renewable energy sources, but there is normally at least one viable option. For example, we can’t always rely on solar power here in the UK, but wind power is a much more reliable source!

  • Renewable doesn’t always mean sustainable. As useful as many renewable energy resources are, not all of them are great for the environment. Large hydropower dams have damaged river ecology and displaced people from their homes, among other negative consequences.

What types of renewable energy are there?

Wind energy

One of the most popular forms of renewable energy in the UK, wind farms are becoming a common sight. Wind is also the cheapest renewable source of energy in the US. The mechanics are fairly simple; the wind pushes turbines which spin to drive generators, which then create electricity. Harnessing the wind for power first started over 7,000 years ago, and we’re certain it’ll continue to be used for thousands of years in the future.

Solar energy

Sunlight is both powerful and abundant here on Earth, making it the perfect power source for humans. We’ve already been taking advantage of it for aeons, whether to stay warm or grow food. To give you an idea about the amount of solar energy naturally produced on earth, more energy comes from the sun in one hour than we use globally in an entire year. Imagine if we could store that? Of course, not everywhere is sunny, but smaller amounts of solar power can be created on a cloudy day.

You’re probably familiar with solar panels, but how do they work? They are made from silicon photovoltaic (PV) cells which absorb sunlight and convert it into electrical charges. Alternatively, large solar power plants sometimes use mirrors to reflect sunlight onto receivers, which then collect solar power and convert it to heat. This heat can be stored or used to produce electricity.

Hydroelectric energy

Hydroelectric energy, or hydropower, uses water to create energy and is the world’s biggest renewable energy source by far. Most commonly, hydropower plants make use of rivers or reservoirs to create energy. Sometimes they use dams to store river water in a reservoir, and sometimes a diversion will push part of a river through a canal or penstock. Typically, water will be used to spin turbines that activate generators to produce electricity. 

Theoretically, hydropower is a clean energy source, but there are definitely some issues that arise from its use. Although hydropower doesn’t produce greenhouse gases, hydropower facilities harm homes and wildlife. Reservoirs may replace homes, wildlife and important natural or archaeological sites. Also, there can be risks for fish that live in the rivers or reservoirs, including entrapment and changing water quality.

Tidal energy

Tidal energy is another form of hydropower, but it only makes use of the ocean tide. Similarly to other types of hydropower, it relies on water driving turbine generators, but it is more consistent due to the predictability of tides. Tidal and wave energy projects are still pretty new, so they are currently quite expensive. They also have the potential to cause environmental concern, as does anything that involves manipulating an area where wildlife live. However, there is still progress to be made in the tidal energy industry, so perhaps it’ll become more viable.

Biomass energy

Biomass consists of anything that comes from animals and plants, such as wood, crops and even garbage. Energy is created when biomass is burned, releasing heat that can generate electricity using a steam turbine. However, if burning materials doesn’t sound very environmentally friendly to you, you’d be right. Some evidence suggests that burning some forms of biomass actually results in higher carbon emissions than burning fossil fuels. So, perhaps we don’t want to rely on biomass energy in the future, even though it’s a renewable source.

Geothermal energy

This renewable energy source involves harnessing the natural heat underneath the surface of the earth. Geothermal energy has actually been used for thousands of years in some places for heating and cooking purposes, and it can be used directly to heat homes or generate electricity. The energy isn’t intermittent like sun or wind, so is always readily available.

However, there are some downsides, such as the bad smell that comes from hydrogen sulfide, and potential mini tremors caused by geothermal power plants. Geothermal energy can only be harnessed in countries where there are volcanoes or hot springs, as all of its activity is confined to the boundaries of tectonic plates.

Nuclear energy

You may be surprised to see nuclear energy here, but it is technically a renewable energy source. However, the material used in nuclear power plants is a very rare form of uranium, U-235, which is not renewable. Although nuclear power plants do not cause air pollution, emit greenhouse gases or destroy the environment, they can be very hard to run safely and have their fair share of risk. 

As you probably know, nuclear energy produces radioactive material, and that’s not something we want around. However, you might be curious to discover that fossil fuels have caused far more deaths than nuclear energy has. Nuclear energy results in 99.8% fewer deaths than brown coal; 99.7% fewer than coal; 99.6% fewer than oil; and 97.5% fewer than gas. So maybe we shouldn’t be so quick to shut down nuclear energy as a potential resource.

How much of the world’s power is renewable?

Now we’ve gone over all of the main types of renewable energy, let’s find out how much of the world’s power is actually renewable right now. IEA’s Global Energy Review 2020 showed that the share of renewables in global electricity generation was at 28% at the beginning of 2020, compared to 26% at the start of 2019. 

If we look even further back to 2010, we can see just how much things have changed. Coal was on the rise in the US, while wind and solar power comprised just 1% of the country’s energy. The 2011 issue of Renewable Energy Focus magazine stated that the share of global energy consumption from renewable sources was 3.3% in 2010. This means we’ve made a huge jump towards renewable energy production and consumption, and we’ve certainly stopped viewing coal as some kind of magic fuel, the answer to all of our energy needs.

Something else to note, is where our renewable energy is coming from. IEA’s review also found that in 2010, hydropower provided 77% of green power, but now that has fallen to 45%. This is a good thing, as some forms of hydropower such as large dams are not environmentally friendly. More sustainable options such as solar and wind power have been taking over, as the review states that solar power capacity has increased by 18 times since 2010, and wind power has increased by four times. 

Which country uses the most renewable energy?

Currently, Iceland is the worldwide leader in renewable energy, and it is the only country in the world to obtain 100% of its energy from renewable resources. 87% of this is from hydropower, and 13% is from geothermal power, which is possible due to a large number of naturally occurring hot springs and abundance of volcanoes.

Other countries doing well on the renewable energy front are Costa Rica, Nicaragua, Sweden, Germany and Scotland. China is actually the world’s biggest investor in renewable energy, and they own six of the world’s largest solar module manufacturing firms and the largest wind-turbine manufacturer. The US also invests in a lot of renewable energy, having wind energy capacity nearly as large as China. However, both China and the US create a lot of pollution and use a large amount of energy, so their interest in renewables doesn’t quite make them green. Not yet, anyway.

Is there a future in renewable energy?

If you’re wondering whether there is actually a viable future in renewable energy, the answer is a resounding yes. The IEA Renewables 2020 report suggests that renewable energy will overtake coal and become the biggest source of electricity generation globally in 2025. By then, renewables are forecasted to supply one-third of the world’s electricity. Of course, we will need effective governance to achieve these goals, which you can learn more about in our Transforming Energy Systems: Why Governance Matters course. 

Is renewable energy profitable?

One of the reasons why there is such a positive future for renewable energy is because it is actually more profitable than energy from fossil fuels. The energy from wind farms, solar plants and hydropower plants arrive for free, as long as the weather allows it. The same cannot be said for oil and gas, which have to be collected and refined or turned into something else.

A Joint Report by the International Energy Agency and the Centre for Climate Finance & Investment was published by Imperial College London last year, after analysing the rate of return on energy investments in renewables and fossil fuels over the last five and ten years. The study found that in the space of 5 years, investments in renewable energy in the UK generated returns of 75.4% compared to 8.8% for fossil fuels. In France and Germany, the disparity is even more shocking, with returns of 178.2% from renewables and -20.7% for fossil fuel investments.

Figures like these show that powering the planet using renewable energy is not merely an idealist or utopian idea, with no financial basis in the real world. There is real evidence that switching to renewable energy is better for our wallets, as well as for the environment.

Can the world thrive on 100% renewable energy?

So, we know that renewable energy can be more profitable than fossil fuels, but is it possible for the world to thrive using 100% green energy? The short answer is yes. As soon as 2050, solar and wind energy will be powering half of the world, according to BloombergNEF forecasts.

We must take action quickly, as global temperatures could rise to 1.5 degrees Celsius above pre-industrial levels between 2030 and 2052 if global warming keeps increasing at the same rate as it is now. This may not sound like much, but a one- to two-degree drop was enough to send the Earth into a Little Ice Age in the past.

There was also a very in-depth study carried out by a Stanford University researcher in 2017, published in the Joule journal. The extensive study performed an analysis of the 139 countries that produce 99% of the world’s carbon emissions. Renewable energy roadmaps were created, providing overviews of how each of these countries could transition entirely to renewable energy sources, and the researchers explain how these transitions mean we could avoid global warming, help the planet and provide millions of jobs. 

All of the 139 countries were found to have renewable energy sources within their own borders, meaning they wouldn’t have to rely on anyone else for their energy. Many countries even have enough to rely on renewables for 100% of their energy. Ultimately, the study suggests that the planet would be ready to switch to 100% renewable energy by 2050 if the right plans were carried out.

Final thoughts

We hope this has provided you with an overview of renewable energy and what it could mean for the future of Planet Earth. If you’re interested in learning more about creating a sustainable future, you can try our Tackling Environmental Challenges for a Sustainable Future course or give Exploring Possible Futures: Modeling in Environmental and Energy Economics a try. The future holds a lot of hope for the renewables industry, and it’s important to be aware of the tangible solutions that exist when dealing with global issues. That way, we can help make sure they happen!

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