The future of renewable energy

Power sources that are endlessly renewable are the holy grail for governments across the world and billions of pounds have been invested in research into fusion reactors. If and when the technology is developed, the problem of energy on Earth might well be solved.

But until then, we look to renewable energy sources that can help reduce the amount of greenhouse gases (GHGs) that trap the sun’s heat and are released by burning fossil fuels to generate electricity and heat. In the UK, the majority of the primary energy consumed within the UK (78.4%) is from coal, oil and gas fossil fuels. (1)

The government’s intention is that by 2030, 95% of British electricity could be low-carbon; and by 2035, the country’s electricity system could be fully decarbonised, subject to security of supply. (2)

In the UK, renewable energy can be broadly defined as clean, sustainable, accessible, reliable and affordable with the main sources being:

·         Wind

·         Solar

·         Hydro

·         Bioenergy

·         Geothermal

Wind power

Wind power harnesses the dynamic energy of air movement through large wind turbines, either offshore or on land. The principle has been around for thousands of years but technologies have rapidly developed over the past few years to optimise energy production.

The government advises that offshore wind will produce 40GW of energy by 2030 and plans that all of the UK’s energy will be from clean sources by 2035. (3) (© Crown copyright 2024. OGL). There are no targets currently for onshore wind energy production in England.

As wind power develops, the UK would need to develop more energy storage, either in batteries or other methods such as liquid air, a technology which uses surplus night-time electricity from wind farms to compress air so that it becomes a liquid at -196 Celsius. This will be warmed and will rapidly expand when there is a peak in demand in a day or a month, and the rush of air drives a turbine to generate electricity.

Solar power

The power of the sun is truly astonishing. According to the US Department of Energy,  every second, 173,000 terawatts of solar energy strikes the Earth and that’s more than 10,000 times the world’s total energy use. It’s not only the most abundant of all energy resources, but we can also even harvest it in cloudy weather. (4)

Solar technologies convert sunlight into electrical energy either through photovoltaic panels or through mirrors that concentrate solar radiation, providing provide heat, cooling, natural lighting, electricity and fuel.

You don’t necessarily need the sun blazing for solar photovoltaic panels (PV) to work. Even though they obviously produce more power during a sunny day, they can still produce a considerable amount of energy when the days are cloudy. Solar PVs use light to produce electricity, not heat.

Solar panels are made of solar cells which are basically a sandwich made up of two slices of semi-conducting material, usually silicon. They work by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity.

The cost of manufacturing solar panels has fallen in the past decade, making them more affordable, with many manufacturers advising that they have a lifespan of 25 years.

Hydropower

Hydropower harnesses the energy of water moving from higher to lower elevations. It can be generated from reservoirs and rivers. Reservoir hydropower plants rely on stored water in a reservoir, while run-of-river hydropower plants harness energy from the available flow of the river.

Hydropower reservoirs often have multiple uses – providing drinking water, water for irrigation, flood and drought control, navigation services, as well as energy supply.

Bioenergy

Bioenergy is electricity and gas generated from organic matter (biomass) – plants, timber, agricultural and food waste or sewage. Dry material like wood pellets are burnt in boilers or furnaces to heat water and create steam to drive turbines that generate electricity.

Food waste and other wet materials are placed in sealed tanks where they rot and produce methane gas (biogas), which can be burnt to generate electricity, injected into the national gas grid for cooking and heating. While burning biomass releases carbon dioxide, it is neutral in effect, and far less than that released when burning fossil fuels.

Geothermal energy 

Geothermal energy works by capturing heat from the Earth’s interior and the technology for electricity generation from hydrothermal reservoirs has been in use for over a century. The mature and reliable technology extracts hot fluids from the reservoirs, which are brought to the surface and used to generate electricity.

Shallow geothermal resources are becoming more popular. The upper crust of ground, around 10-15 m deep, is heated by the sun, acting as a heat store. With ground source heat pumps, this energy is extracted and used to heat and cool homes and buildings.

Heat pump energy

Ground source heat pumps work by taking heat from the ground outside or from a body of water, using either closed loop piping for the ground or open loop piping for water.

For the ground-based system, a water and anti-freeze mix is pumped around the buried piping array, and absorbs heat from the sun that is captured in the earth. This is extracted using compression and expansion technology.

Heat pump technology is very efficient and they currently have similar running costs to gas boilers. Reducing the price of electricity relative to gas would make heat pumps more competitive. Additional savings are possible with flexible electricity tariffs. (5)

And the savings could  be boosted further with other sustainable technologies like solar PV, to provide electricity to power the extractor process.

Heat pumps are used to extract thermal energy in the outside air or from the ground or water and moving it inside where it is compressed and the heat transferred using a series of coils. An air source heat pump is fitted outside a building and has a system of coils filled with refrigerant liquid.

It works by drawing in air via a fan or impeller and the liquid in the coils absorbs heat from the air and evaporates. This gas passes through a compressor which greatly increases the temperature.

As an energy technology, heat pumps are very efficient and clean. While they do use electricity to power a part of the operation, they don’t burn fossil fuels directly to generate heat. What’s more, they work effectively in temperate climates like the UK and deliver heating even when external  temperatures are as low.

We can all contribute to a cleaner future as the energy markets become stable again by choosing green energy suppliers that provide power from renewable sources and look to installing heating technologies such as heat pumps and energy generators like solar photovoltaic panels.

This article has been written by SaveMoneyCutCarbon and is correct at (May 2024). This content does not constitute advice and is for general guidance and educational purposes only. It should not be circulated or used in presentations or materials without prior approvals and does not constitute legal advice or formal training. Always undertake your own research before taking any action. It is recommended that specific professional advice relevant to any particular or individual situation is sought before acting on any information given (© 2024 SaveMoneyCutCarbon.com)

Bibliography:

1 Gov.uk National Statistics (Accessed May 2024)  Digest of UK Energy Statistics (DUKES): energy https://www.gov.uk/government/statistics/energy-chapter-1-digest-of-united-kingdom-energy-statistics-dukes (© Crown copyright 2024. OGL).

2  HM Government (April 2022) British Energy Security Strategy, Secure, clean and affordable British energy for the long term  https://assets.publishing.service.gov.uk/media/626112c0e90e07168e3fdba3/british-energy-security-strategy-web-accessible.pdf (© Crown copyright 2024. OGL).

3 Gov.uk Press Release (Accessed May 2024) New plans to make UK world leader in green energy https://www.gov.uk/government/news/new-plans-to-make-uk-world-leader-in-green-energy (© Crown copyright 2024. OGL).

4   Energy.Gov (Accessed May 2024) Top 6 Things You Didn’t Know About Solar Energy https://www.energy.gov/articles/top-6-things-you-didnt-know-about-solar-energy

5  Ben Harris & Alan Walker UK Parliament Post (July 2023) Heat Pumps https://researchbriefings.files.parliament.uk/documents/POST-PN-0699/POST-PN-0699.pdf (Contains Parliamentary information licensed under the Open Parliament Licence v3.0.)