What is renewable energy?

Renewable energy explained

What is renewable energy?
Renewable energy is energy from natural sources that can be easily recycled or replenished. The key test is whether the source can be replenished more quickly than it is used. If so, it is a form of renewable energy.

Solar power, wind power and hydroelectric power are examples of renewable energy — sunlight, wind and flowing water are all natural sources that are continually available. This is in contrast with non-renewable energy sources, such as fossil fuels, which would take millions of years to replace.

Renewable energy is sometimes taken to mean the same thing as clean energy and green energy. But there are some subtle differences: 

• Clean energy is energy that doesn’t pollute the air. 

• Green energy comes from environmentally friendly and natural sources. 

Biomass energy is renewable but can’t be considered clean or green because carbon is released when organic materials are burnt. Nuclear energy is clean because there are no emissions, but it is not renewable or green.

What is non-renewable energy?
Non-renewable energy is the opposite of renewable energy — just as its name suggests. Non-renewable energy sources are not easily replaced and cannot be replenished or recycled faster than they are being used.

Fossil fuels like coal, gas and oil are the most obvious examples of non-renewable energy. Non-renewable energy sources are now known to contribute to global warming due to the greenhouse gases that are emitted when fossil fuels are burned. 

Types of renewable energy sources 

There are various different types of renewable energy sources in Northern Ireland and around the world. Let’s take a look at the six main sources of renewable energy, how they work and the role they play in meeting our local energy demand.

Solar energy 
Solar energy is generated by converting energy from the sun into electricity. Photons — small packets of energy that make up sunlight — produce an electric charge when they hit a solar panel made of silicon or another semiconductor. This charge travels through the solar panel  and is converted into the electricity we need to power our homes.

Solar energy generates 4.5% of the electricity used in the UK. Just under 2% of the electricity used in Northern Ireland comes from solar.

Wind energy 
Wind energy uses the natural power of the wind to generate electricity. The wind drives large wind turbines, which are placed at altitude or in exposed areas to maximise the strength of the wind. When the turbines rotate they drive generators, which create electricity.

Wind power has been used by humans for thousands of years. Sailing ships and boats have been driven by wind power for at least 5,500 years. Windmills — using the power of the wind to grind grain — were developed before the 9th century.

Wind power in Northern Ireland accounts for 43.5% of all electricity used. This compares to 29.3% of electricity used in the UK.

Biomass energy
Biomass energy uses organic materials to create electricity. This is achieved by burning suitable materials from agricultural, industrial and household waste. Wood, charcoal, manure and agricultural crops are some of the things used to generate biomass energy.

In that respect, biomass is one of the oldest forms of energy — people have always burned those waste materials to create heat and light. Modern biomass systems typically take byproducts and offcuts that would otherwise turn to compost and convert them into a low-carbon source of energy.

Biomass and biogas generate 18.8% of Northern Ireland’s electricity. The equivalent figure across the UK is 5.3%.

Hydroelectric energy 
Hydroelectric energy  channels the energy of moving water to produce electricity. The powerful flow of water from higher elevations to lower elevations is harnessed to drive turbines, which power generators and create electricity. Hydropower is usually generated on reservoirs but can also be achieved on rivers.

In the late 1800s, more than 1,000 water-powered mills were providing hydroelectric power in Northern Ireland. They were the main source of electricity for many rural communities from the early-1900s until the 1960s when cheaper electricity from fossil fuels became more widely available.

Hydroelectric energy is a very small part of Northern Ireland’s energy mix. Less than 1% of electricity comes from hydro — and the figure is approximately the same throughout the UK.

Tidal energy
Tidal energy uses the natural movement of seawater to generate electricity. The large flow of water in at high tide and out at low tide drives turbines to create power. Tidal and wave energy usually involves building barriers across a bay or estuary. Although the flow isn’t consistent, it is powerful and predictable. 

Studies into using tide mills to generate electricity have been around since 1920 but the world's first tidal power station — Rance Tidal Power Station in France — didn't open until 1966.

Tidal energy and wave energy contribute only around 1% of the UK’s electricity and don’t contribute to Northern Ireland’s power network.

Geothermal energy 
Geothermal energy uses the heat stored beneath the earth’s crust to generate electricity. Deep holes into the earth’s crust are filled with water. When the water evaporates because of the heat, the steam and vapour produced are used to drive turbines and create electricity.

People have been using the geothermal warmth of hot springs for centuries, and to create heating systems since the 19th century. The first commercial geothermal power plant was built in Italy in 1911.

Geothermal energy is not part of the energy mix in Northern Ireland or the UK. It is a more popular type of renewable energy in countries with naturally occurring geothermal springs.

Advantages of renewable energy

There are several key benefits of renewable energy for the environment and our communities. They include:

• Environmental benefits - Renewable energy sources help to tackle climate change by reducing carbon emissions.
• Public health benefits - Zero-emission renewable energy sources help to improve air quality, which reduces the risk of many respiratory diseases.
• Reliable source of energy - Renewable energy can always be generated locally, which means geopolitical and supply chain problems don’t disrupt energy supplies. 
• Infinite energy source - Unlike non-renewable energy sources, there is an infinite amount of renewable energy sources.
• Increased job opportunities - Investing in new renewable energy infrastructure can increase job opportunities.
• Lower maintenance costs - Generating renewable energy needs far less maintenance than fossil fuel power stations because there are fewer moving parts and less combustion involved. 

Renewable energy in Northern Ireland 

History of renewable energy in Northern Ireland
There is a strong history of renewable energy in Northern Ireland. Before the mid-1800s, almost all energy used in Northern Ireland and around the world was renewable. This includes biomass energy to fuel fires and the use of wind to power windmills and drive ships. There is also a longstanding heritage of hydroelectric power in Northern Ireland.

Future of renewable energy in Northern Ireland 
Northern Ireland gets 51% of its energy from renewable sources at the moment, with 85.3% of that coming from wind power. As we move towards a net zero future, even more of our electricity will be generated using renewable power. The Climate Change Act (Northern Ireland) 2022 sets targets for 80% of electricity to come from renewables by 2030 and net zero carbon emissions by 2050.

There are plans for investment in geothermal energy, green hydrogen production and battery energy storage systems (BESS) to stockpile energy from wind, solar and other renewable sources when a surplus is generated to enhance the use of renewable energy in Northern Ireland.

Power NI Renewables

We’re committed to helping Northern Ireland achieve its renewable energy targets. One of the key ways we’re doing that is by supporting our customers when they invest in renewable generators.

With our microgeneration and Power Purchase Agreements (PPAs), you can sell energy generated from renewable sources back to us. Earn money from your wind, hydro, solar and other renewable generators. Protect the environment and help Northern Ireland towards its net zero goal.