The future of renewable energy
Written by Linda Allardyce
Just the thought of clean energy can make you feel fresher and more positive about the future. But is it the solution to a rapidly warming world?
Power sources that are endlessly renewable are the holy grail for every government across the world and billions of pounds have been invested in research into fusion reactors. If and when the technology is developed, that’s the problem of energy on Earth solved.
But until then, we look to renewable energy sources that will help us 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.
Coal, oil and gas are the largest contributors to global climate change, accounting for over 75% of global greenhouse gas emissions and nearly 90% of all carbon dioxide emissions. These need to be reduced by almost half by 2030 and reach net-zero by 2050.
Fossil fuels are used to produce more than 80% of global energy production, but across the world, about 29% of electricity currently comes from renewable sources.
In the UK, renewable energy can be broadly defined as clean, sustainable, accessible, reliable and affordable with the main sources being:
In the second quarter of this year, renewables’ share of UK electricity generation was 38.6%.
It’s worth remembering that the “cheap” dirty fuels are only priced lower through subsidies and tax breaks. When health and environmental damages are added, around $5.9 trillion was spent on subsidising the fossil fuel industry in 2020, according to International Monetary Fund figures.
In comparison, the International Energy Agency estimates that about $4 trillion a year invested in renewable energy until 2030 would enable governments to reach net-zero emissions by 2050.
Renewable energy is the cheapest power option in most parts of the world today, according to the International Renewable Energy Agency (IRENA). The cost of electricity from solar power fell by 85% between 2010 and 2020. Costs of onshore and offshore wind energy fell by 56% and 48% respectively.
Cheap electricity from renewable sources could provide 65% of the world’s total electricity supply within eight years and decarbonise 90% of the power sector by 2050. As prices for gas and oil continue to rise, renewable energy technologies are becoming increasingly competitive, according to the International Energy Agency (IEA).
And there are great benefits for economies. The UN advises that every dollar of investment in renewables creates three times more jobs than in the fossil fuel industry. While around 5 million jobs could be lost in fossil fuel production by 2030, an estimated 14 million new jobs would be created in clean energy. With further expansion in energy-related industries, more than 30 million jobs could be created in clean energy, efficiency, and low-emissions technologies by 2030.
What’s more, pollution and climate improvements alone could save the world up to $4.2 trillion a year by 2030, according to IRENA. And renewables will help to develop a reliable energy system that is less susceptible to market shocks, and unstable and predatory producers. It should be a much more resilient and secure environment.
Wind power harnesses the dynamic energy of air movement through large wind turbines, either offshore or on land. The principal has been around for thousands of years but technologies have rapidly developed over the past few years to optimise energy production.
We have more than 11,000 offshore and onshore wind turbines, producing nearly a quarter of the UK’s electricity. In fact, we currently have the largest offshore wind-power capacity in the world.
The government plans that all of the UK’s energy will be from clean sources by 2035 and has set a target of 50 gigawatts (GW) of UK electricity to be generated by wind by the end of the decade. To meet this target, offshore wind capacity would need to quadruple by 2030, and onshore wind capacity double. That means anything between 1,000 and 2,000 new wind farms.
There is renewed commitment to onshore wind, which is far cheaper than offshore production, but new projects have declined by 94% since 2015 after government subsidies were ended and stricter planning regulations were introduced. Times, and attitudes, change with 70% of people now supporting onshore wind in the UK, according to the Department for Business, Energy & Industrial Strategy
As wind power develops, the UK will also need much 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.
The power of the sun is truly astonishing. 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.
So, despite having a bit of a reputation for grey and cloudy conditions, UK actually has more than enough sunlight to power solar panels. We get the same amount of solar energy as parts of France and Spain.
In fact, we get around 60% of the solar radiation you find in the Equator and some southern parts of the UK have sunlight levels comparable to Germany, one of the biggest markets for photovoltaics in the world.
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.
Solar power currently contributes 1.8% to the UK renewable mix, a 24% increase compared to the end of 2020. It’s a popular form of low-maintenance domestic energy in the UK with nearly 1 million homes benefiting from solar photovoltaics (PV) for electricity, and 100,000 having solar thermal for hot water, according to figures from trade association Solar Energy UK.
The UK reached 14.6GW of solar capacity at the end of December 2021. The 730MW of solar generation capacity added in the UK last year is a 36% rise on the 538MW of solar added in 2020, driven largely by rocketing energy prices.
The cost of manufacturing solar panels has plummeted dramatically in the past decade, making them not only affordable but often the cheapest form of electricity, and they have a lifespan of 25 years.
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.
The UK has a total hydropower installed capacity of over 4,700 MW, including over 2,800 MW of pumped storage. The vast majority of installed capacity is located in the wet and mountainous regions of Wales and northwest Scotland.
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 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 with average savings in excess of 40-60% for ground or air source pumps. Heat pump systems are 400% more efficient that standard heating systems because they extract and move heat rather than generate it through costly combustion.
And the savings can 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.