Written by Tom Gill Updated on 30 October 2023 ✔ Solar power is the fastest growing renewable energy source✔ Wind power produces the most green electricity in the UK✔ We need mixture of renewable energy sources to properly replace fossil fuelsThe world is gradually switching to renewable energy. In fact, 95% of the increase in global power capacity is expected to come from green sources by 2026 (International Energy Agency, 2021).Renewable energy sources are better for the environment, cheaper than fossil fuels, and effectively unlimited.But which type of renewable energy is the best? We’ve investigated the major ones – including solar power, wind power, and geothermal energy – further below. Read on to find out. What's on this page? 01 What’s the best type of renewable energy? 02 Summary 03 FAQs Although some energy sources boast more advantages than others, there isn’t actually one best type of renewable energy. So is that the end of the article already? No, because what the world needs to do is to transition to a mix of renewable energy sources.This is because renewable energy sources aren't capable of producing a constant output, like fossil fuels are.The sun isn’t always shining and the wind isn’t always blowing, so the ideal situation is to have the infrastructure to support many different types of renewable energy, all working in tandem.And of course, the key benefit to renewable energy is moving away from the high carbon emissions produced by fossil fuels, which is the leading cause of climate change.So, even though we’ve not committed to choosing one source of renewable energy as the best, here are our top picks. Solar power Pros Unlimited source of energy Long lifespan Requires very little maintenance Saves on energy bills Reduces strain on the grid Cons Dependent on the weather The panels are challenging to recycle High upfront cost Storing solar energy is expensive Takes up a lot of space Solar power, in the simplest terms, is energy generated from the sun. It’s one of the most recognisable forms of renewable energy and you’d be hard-pressed to find someone who isn’t aware of what a solar panel is.The main benefit of solar power is that it’s effectively an unlimited source of energy – the sun isn’t going anywhere any time soon and is capable of powering the entire world (in theory).To do so, we’d have to cover an area of roughly 115,625 square miles (mi²) with solar panels. For context, the total land surface area of Earth is roughly 57,308,738 mi², so we’d need just 0.2% of this to provide electricity to everyone using solar power alone.Solar power are worth it at the residential scale too – it lowers energy bills, reduces a home’s carbon emissions, and increases independence from the grid.It isn’t perfect though, as solar requires a lot of space and, naturally, needs sunlight to function.You can mitigate the need for sunlight by installing large-scale solar batteries, which you charge during the day for use at night. However, these are expensive and typically last just half the lifespan of a solar panel array.There’s also the issue of recycling solar panels, which is a problem the world is currently having to come to terms with. This is because widespread solar panel adoption has only been developing over the past 20 years or so, and solar panels typically last 25 years or more.Recycling centres do exist and there’s a lot of research going into solar recycling infrastructure, but it’s still early days.Wind power Pros Zero emissions Low operating costs Wind power is comparatively cheap to build Cons Noise and visual pollution Wind is intermittent Location dependent Can impact wildlife Like solar, wind power is one of the best-known forms of renewable energy. Most people have seen a wind turbine, so it’s hardly surprising that they’re responsible for the majority of the UK’s renewable energy generation.In fact, wind power contributed a whopping 26.8% of all electricity generation to the UK’s grid in 2022. Solar and hydropower made up just 4.4% and 1.8%, respectively.It’s an ideal source of renewable energy because wind is an inexhaustible resource, meaning once a wind farm is up and running, we can effectively just leave it to generate free, clean electricity (barring occasional maintenance).Wind turbines don’t require much investment either, especially when compared to nuclear power plants and even utility-scale solar farms. It costs around £37 per MWh for offshore wind, and roughly £139 per MWh for nuclear, according to asset management firm Lazard.However, the noise and visual pollution created by turbines are the main downsides to wind power.Though visual pollution is subjective, noise pollution is less so and living near wind turbines can mean putting up with a humming sound – around 43 decibels at a distance of 300m (most fridges have an ambient noise level of 32 to 47 decibels).Turbines can also impact wildlife, with birds being the most widely affected, as they’re known to occasionally fly into the blades. Experiments involving painting turbine blades black are underway, and have shown that this can help stop birds hitting them.It’s also challenging to install wind turbines in urban areas, particularly as wind flow tends to be lower. You typically need to install wind turbines either in more rural locations, or offshore, but this then introduces the problem of sending the electricity generated over much greater distances.Despite the disadvantages, wind turbines remain a popular renewable energy source, as our National Home Energy Survey revealed. And, wind is cheaper than fossil fuels – wind (and solar) projects cost around 40% less than new coal or gas projects.Tidal power Pros Zero emissions Predictable electricity generation High power output Cons Requires specific conditions Expensive to build Environmental impact Tidal power relies on a similar concept to wind power – using a force of nature to turn turbines, which generates electricity.The difference is that tidal power uses the ebb and flow of coastal tides, instead of wind.It’s this difference that gives tidal power an advantage over wind, because water is a lot denser – up to 800 times more dense than wind.That enables a tidal turbine to produce substantially more energy than a wind turbine of the same size.In theory, tidal power could produce more electricity using only a fraction of the space offshore wind farms use.Plus, tides are easily predictable, so we’d be able to plan around power needs accurately, unlike wind.The downside? Tidal power needs specific conditions to work effectively. Not only do turbines need to be installed on coastlines, but they also need to be in locations where the tide rises and falls enough to power them, which isn’tThey’re also typically more expensive than wind turbines – £178 per MWh versus £37 per MWh – because they have to be much stronger to withstand the greater forces of water. Tidal turbines are also usually housed within a tidal barrage (a dam that funnels tidal currents), which requires an expensive concrete structure.There’s the threat to wildlife too, as marine life can find itself caught in the turbines and the low-level noise generated by the turbines can impact some animals, such as seals.Biomass Pros Reduces waste in landfills Less polluting than fossil fuels Easily accessible Carbon neutral (in theory) Cons Not as efficient as fossil fuels Still releases some emissions Can lead to deforestation Biomass energy is one of the less-known renewable sources of energy, at least when compared to solar, wind, and hydropower. But really, we’ve been using biomass since the first humans discovered the ability to make fire.This energy source is caused by burning biological matter, including plants, wood, and waste. The reason it’s considered a renewable source of energy is that, in theory, we can balance the emissions released from burning it.So as plants and trees absorb carbon, burning them to produce energy releases it back, and then it’s reabsorbed by new plants and trees. Sounds ideal right? Well, it’s a bit more complicated because this balancing act isn’t an exact science.You need to make sure the plants and trees you replace those you’ve cut down actually absorb the same amount of carbon emissions that are released when burning them. And that means planning in advance to allow them to grow in time to properly absorb the CO2.Additionally, there’s the reality that some companies burning biomass for fuel don’t take this into account. Drax, an energy company once labelled western Europe’s biggest polluter, boldly claimed it’d be carbon neutral by 2029.Instead, it found itself widely criticised after it emerged the company had been importing wood from Canada – a journey of over 3,600 miles. The UK imports wood pellets from the US too, which amounts to 13-16 million tonnes of CO2 being released into the atmosphere.Hydropower Pros Constant source of energy Meets peak energy demand Can help with irrigation Low costs once up and running Cons Huge upfront costs Potential environmental damage Increases flood risk Can displace people Hydropower is currently the world’s largest renewable energy source – the global hydroelectric installed capacity exceeds 1,295 gigawatts (GW) which is around 18% of total power generation (IEA, 2023).The reason? Hydropower is an incredibly powerful source of renewable energy and can provide power to the grid immediately. The water is almost always flowing and, unlike wind and solar power, isn’t affected by either the weather or the time of day.This reliability means hydropower can be called upon to meet peak demand for electricity, which will be hugely important in a post-fossil fuel world. Droughts can affect this though, as was the case in Norway in 2022 when hydropower fell to its lowest point in over 20 years.The problems with hydropower, however, are its huge upfront costs and high potential to cause environmental damage. Costs eventually even out from savings, but the impact on the land will be felt for decades, if not centuries.Building the infrastructure for hydropower involves blocking off vast quantities of water, leading to increased flood risk, droughts, and destruction of wildlife habitats.Additionally, local communities can be displaced when a dam is built, and sometimes people who have lived in a location for generations are forced to evacuate their homes. Indigenous peoples have been displaced by hydroelectric dams on more than a few occasions.So for all the good hydropower offers with its constant source of clean, renewable energy, there are obvious drawbacks.Geothermal Pros Huge energy potential Zero emissions once up and running Constant, stable source of energy Cons Location specific High upfront costs Potential environmental issues Geothermal energy is the process of harnessing the Earth’s raw energy to either heat homes, or use the warmth from the planet’s crust to turn turbines, generating electricity. This is done by using steam from reservoirs of hot water found deep underground.Compared to wind, solar, and hydropower, geothermal energy is a tiny proportion of the world’s renewable electricity generation – just 0.5% (IRENA, 2023).Its main advantage is that, as long as the Earth keeps spinning, the supply of energy is unlimited. And it’s constant, meaning we can better plan around consumption trends and meet peak electricity demand whenever it’s required.As it comes from deep within the ground, geothermal energy isn’t typically affected by the weather either. This is what makes ground source heat pumps so effective, because the soil temperature remains constant throughout the year.Geothermal energy is incredibly clean too, at least once it’s up and running. There’ll be a small amount of carbon emissions during the construction of geothermal power plants, and in installing technology such as ground source heat pumps in homes. The emissions released pale in comparison to the impact of fossil fuels however.Large scale geothermal energy projects can release more greenhouse gases, such as hydrogen sulphide, carbon dioxide, methane and ammonia.It's also expensive too, with residential-scale ground source heat pumps typically costing between £24,000 and £49,000 to install. Plus, you need the right location because you can't just put a geothermal plant anywhere and expect the ideal underground conditions.Some countries, such as Iceland, are naturally blessed with geothermal reservoirs. Other countries have to account for the fact that transporting geothermal energy over long distances means expecting high losses of energy. SummaryWhile there is no objective choice for the ‘best’ renewable energy source, it’s important to note that the world needs to transition to using a mix of them all.The most important thing is that we move towards a fully renewable world and away from fossil fuels quickly, as continuing to burn gas and oil will only accelerate the impact of climate change. FAQs Which renewable energy is best for the UK? Offshore and onshore wind are the best sources of renewable energy for the UK because it’s a very breezy country – especially in certain areas, like Scotland. It already accounts for over a quarter of our energy generation, and it’s been proven that wind could power the entire country if enough turbines were built.In fact, we’d only need around 7,000 large wind turbines to provide electricity for every UK household. What is the fastest growing renewable energy source in the UK? Solar power is the fastest growing source of renewable energy in the UK, going from 3,000 installations per month in 2016, to over 15,000 (MCS, 2023) a month in 2023.Plus, this growth has come after the deployment of solar power slowed when subsidies, such as the Feed-In Tariff, ended. What renewable energy source releases the least emissions? Wind power is currently the cleanest form of renewable energy because it takes the least amount of refining and processing of materials compared to other sources, such as solar power.Advancements in technology have meant wind turbines are more durable than they were in the past, and their lifespan has continued to increase. Most modern wind turbines can be expected to continue producing green electricity for 25 years or more. Written by: Tom Gill Writer Tom joined The Eco Experts over a year ago and has since covered the carbon footprint of the Roman Empire, profiled the world’s largest solar farms, and investigated what a 100% renewable UK would look like. Tom has a particular interest in the global energy market and how it works, including the ongoing semiconductor shortage, the future of hydrogen, and Cornwall's growing lithium industry.