Green energy explained

Green energy and renewable energy are phrases you’ll have heard a great deal in recent years. But what exactly is green energy? We’re here to clear up any confusion you might have around green and renewable energy.

 Solar panels on a house roof

What is renewable energy? 

Renewable energy is energy that comes from renewable sources. These resources aren’t used up but are naturally replenished. Good examples include wind, sunlight (solar), and waves (or tides). Non-renewable energy is generated by coal, natural gas and oil among others – often referred to as fossil fuels.


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So what is green energy?

Green energy and renewable energy are the same thing. Energy companies might call their tariff either ‘green’ or ‘renewable’, but these are simply labels that apply to energy generated from replenishable resources.

What are renewable energy sources?

The five main sources of renewable energy are:

  • Wind
    Wind power is captured using on-shore or off-shore wind turbines. Air flow causes the turbine to rotate, generating electricity.
  • Hydro (water)
    Moving water turns a turbine to generate electricity. Due to its density, even slow-moving water can generate electricity. 
    Hydroelectric dams, such as the Three Gorges Dam in China - the biggest in the world - are the traditional way of generating hydroelectric power. In recent years, both wave power and tidal power are beginning to be used.
  • Solar (sunlight)
    Solar panels contribute massively to the generation of renewable energy and are often the cheapest way for you to generate your own renewable electricity. 
    Solar panels continue to drop in price and increase in effectiveness, making them even more cost effective as time goes on.
  • Geothermal
    Geothermal energy is obtained from thermal energy stored in the ground. We’ve used it for thousands of years where it reaches the surface in the form of hot springs e.g. in places like Bath. The same energy that heats the water in the springs can be used to generate electricity. However, drilling to access the thermal energy can often be expensive and make this energy source less than cost effective.
  • Bioenergy
    Bioenergy is generated from biomass - vegetable matter that can be burnt, such as firewood. Other sources include vegetable crops, agricultural and human waste, and even leftover food products such as vegetable oils and animal fats. Biomass can be used to generate gas through a process called anaerobic digestion – a process where micro-organisms break down waste to produce a methane and carbon dioxide-rich biogas.

READ MORE: How to read your energy bill

Upside-down light bulb filled with coins, and a pile of coins with a plant growing out of it/

How is UK renewable energy generated? 

UK renewable energy is generated from a range of resources. As an island, we have a choice of renewable energy resources. Both wind and wave power have considerable potential in the generation of energy, while solar also has a big part to play – although sometimes this seems unlikely when we have one of our wetter summers!

Over the past decade the UK has made considerable progress to phasing out certain types of energy production – especially coal. At the start of summer 2019 various records were broken where no coal was used for power generation at all. A coal-free fortnight in May was the longest period since the world’s first coal-fired generator opened in Holborn in 1882.

This is partly due to the move in recent years from coal-fired power stations to those burning natural gas - still a fossil fuel but with less than half the carbon emissions of coal.

During the coal-free fortnight, renewables stepped into the gap - with wind and solar contributing as much as 35-40% of the UK’s energy needs at some points. This was the third time that year that the record for coal-free electricity has been broken.

In 2019 for the first time, the UK renewable energy percentage was on course to exceed 50% across the whole year. This means we’ll generate more than half our annual energy from non-fossil fuels.

READ MORE: How much do your appliances cost to run?

Green energy companies

So, this all sounds great, but as an energy consumer what can you do? How do you know what energy you’re using? Electricity doesn’t exactly come out of the wires with a label or a different colour.

Well, you have plenty of green tariff options. There are a number of energy companies on the market who deal exclusively in renewable tariffs – such as Pure Planet, Bulb, Octopus, Ecotricity, and Green Energy UK. And all of the Bix Six energy companies - British Gas, EDF, Npower etc. - offer a green or renewable tariff as well.

Isn’t green energy expensive? 

This is often a misconception about green energy. In our experience, green tariffs often work out cheaper, making them not only good for the planet, but also good for your wallet.

How do I find a green supplier?

It couldn’t be easier. Click the COMPARE ENERGY PRICES button at the top of our switching page. When you’re presented with the list of suppliers and prices, simply look for the tariffs labelled as green or renewable

How do I know my energy is green? 

Your supplier will normally explain where they buy their energy from – if you only have an electricity supply then you can be fairly certain that it’s 100% renewable.

Gas is a little trickier – green gas only makes up a small proportion of gas supplies, as its sources are limited – it’s mainly made using anaerobic digestion, but facilities are few and far between.

If you’re on a dual fuel tariff it might be that a proportion of your gas isn’t ‘green’. Your supplier will normally have details of what proportion of their gas is green – and will supply this on the tariff information.

READ MORE: Types of energy tariff explained

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What are the advantages and disadvantages of renewable energy?

The advantages of renewable energy over fossil fuels are spoken about a lot, but it’s important to give a balanced view and mention the downsides too.

  • Renewable resources
    The resources used to generate renewable electricity are effectively infinite, meaning they won’t run out, no matter how much we use. 
    In comparison, fossil fuels are a finite resource – there’s only so much of them available to use, and they’re becoming increasingly more difficult - and expensive - to obtain.
  • Environmental impact
    We all know that renewables are environmentally friendly. Since they emit no or very low levels of carbon or greenhouse gases, they don’t affect climate change or air quality. They also produce very few waste products. Fossil fuels on the other hand, have an environmental impact at every stage from extraction and transportation through to disposal of waste products. The more energy generated by renewables, the lower the impact on the environment we live in.
  • Technology vs. fuel
    Much of the cost in fossil fuels is in the extraction and transportation of the fuel. As the fuel becomes more scarce, it becomes more expensive to extract once the easily accessible sources become depleted. In contrast, with renewables the fuel is effectively free, while the technologies used to access or harness the fuel are dropping in cost all the time. This will continue to be the case as renewable energy suppliers continue to develop their technology. For example, solar panels have become much cheaper over the last decade, at the same time as becoming more effective in capturing the sun’s energy.
  • Construction vs. maintenance
    The majority of the costs associated with renewables are in their initial construction – for example it costs a lot to construct off shore wind turbines and the cabling to connect them to the electricity grid. Extracting fossil fuels are cheaper initially - although building the power stations that burn them are anything but cheap - but do require constant transportation of fuel, alongside ongoing maintenance to keep the power flowing. With renewable energy technology, little maintenance is required once the infrastructure for harnessing the renewable resource has been built – which helps reduce the cost of producing the energy over time.
  • Reliability
    One of the biggest disadvantages of green energy is reliability. When the wind isn’t blowing the turbines don’t turn. If it doesn’t rain the hydroelectric dams don’t work. And at night-time solar is worse than useless. Many of these issues are resolvable using battery storage, where again technology is advancing at an incredible rate. Batteries allow energy to be stored when the resource produces an excess of power and released when the supply is limited. It should also be noted that contrary to popular belief, the sun doesn’t need to be shining for solar panels to work – it just needs daylight.
  • Space
    Renewables require far more space than other forms of power generation – a solar farm or windfarm would need to be spread across hundreds of acres to generate even a proportion of the energy a nuclear power station can generate.

READ MORE: What can I recycle? The recycling confusion demystified

Switching to a green deal

If you want to switch to a green energy deal, click the COMPARE ENERGY PRICES button on our gas and electricity switching page and look for the green tariffs on the results page – compare today to see how you can help save the planet as well as a few quid!

Read our guides for further information on how the switching process works or on the tariffs available to you.