• The range of different energy sources and how suppliers reflect these in your mix​
  • The pros and cons of each type of source​

So, what are the different types of energy sources and how do they work?

What do we mean when we talk about fossil fuels?

Fossil fuels are energy sources formed in the Earth’s crust from decayed organic material. The common fossil fuels are oil, coal, and natural gas.

Although fossil fuels are readily available, efficient and reliable; they cause a huge amount of damage to the environment, contributing heavily to the climate change emergency as well as the detrimental knock on effect of pollution on human health.

They’re also a finite energy resource, so once the oil, gas and coal reserves have been completely used up, there’s nothing more left. It’s been predicted that this could happen in the next 50 years.

Low carbon energy, what's it all about?

Nuclear power is the most affordable, low-carbon energy source currently available to the UK.

Nuclear energy comes from the binding energy that is stored in the centre of an atom and holds it together. To release the energy, the atom has to be split into smaller atoms. This process is called fission.

How does nuclear energy make electricity?

During a reaction the smaller atoms don’t need as much binding energy to hold them together, so the extra energy is released as heat and radiation.

In nuclear power stations, the heat caused by fission is used to boil water into steam. The steam is then used to turn a turbine that drives generators to make electricity.

The nuclear power generation process

How does a nuclear PWR (Pressurised Water Reactor) station work?

The reaction is triggered

The reactor vessel is a tough steel capsule that houses fuel elements – sealed metal cylinders containing uranium. Neutrons are fired at the uranium atoms, causing them to split and release more neutrons. These then hit other atoms, causing more splits, and so the chain reaction continues. It’s this chain reaction that generates the huge amount of heat needed for the next stage.

Water is heated

Water is passed through the reactor vessel, where the chain reaction heats it to around 300°C. The water needs to stay in liquid form for the power station to work, so the pressuriser applies around 155 times atmospheric pressure, to stop it from boiling and evaporating.

Hot water is circulated

A coolant pump then circulates the hot, pressurised water from the reactor vessel through to a steam generator. 

Steam is created

This hot, pressurised water flows through thousands of looped pipes while a second stream of water flows around the outside of the pipes. This water is under much less pressure, so the heat from the pipes boils it into steam.

Steam energy is converted to electrical energy

The steam passes through a series of turbines, and causes them to spin. This converts the steam’s heat energy into mechanical energy. A shaft connects the turbines, which are spinning at 3000 revs per minute, to a generator. The generator then uses an electromagnetic field to convert this mechanical energy into electrical energy. 

Electrical energy is passed to national grid

A transformer converts the electrical energy to the high voltage needed by the national grid.

Electricity is sent through power lines to homes

The national grid uses high voltages to transmit electricity efficiently through the power lines. And at the end of the power lines are the homes, businesses and services that use the electricity. Here, other transformers reduce the voltage back down to a usable level.

The steam is cooled and recycled

Once the steam has done its job in the generator, it needs to be cooled. It is passed over pipes full of cold water pumped in from the sea. These cool the steam and condense it back into water. It’s then piped back into the steam generator, where it can be reheated turned into steam again, keeping the turbines turning and the electricity generation going.

Let's talk about renewable energy...


What is a renewable energy source?

A renewable energy source means energy that is sustainable - something that can't run out, or is endless, like the sun. When you hear the term 'alternative energy' it's usually referring to renewable energy sources too. It means sources of energy that are alternative to the most commonly used non-sustainable sources - like coal.

Solar energy

Sunlight is one of our planet’s most abundant and freely available energy resources. The amount of solar energy that reaches the earth’s surface in one hour is more than the planet’s total energy requirements for a whole year. Although it sounds like a perfect renewable energy source, the amount of solar energy we can use varies according to the time of day and the season of the year as well as geographical location. In the UK, solar energy is an increasingly popular way to supplement your energy usage.

Wind energy

Wind is a plentiful source of clean energy. Wind farms are an increasingly familiar sight in the UK with wind power making an ever-increasing contribution to the National Grid. To harness electricity from wind energy, turbines are used to drive generators which then feed electricity into the National Grid. Although domestic or ‘off-grid’ generation systems are available, not every property is suitable for a domestic wind turbine. Find out more about wind energy on our wind power page.

Hydro energy

As a renewable energy resource, hydro power is one of the most commercially developed. By building a dam or barrier, a large reservoir can be used to create a controlled flow of water that will drive a turbine, generating electricity. This energy source can often be more reliable than solar or wind power (especially if it's tidal rather than river) and also allows electricity to be stored for use when demand reaches a peak. Like wind energy, in certain situations hydro can be more viable as a commercial energy source (dependant on type and compared to other sources of energy) but depending very much on the type of property, it can be used for domestic, ‘off-grid’ generation. Find out more by visiting our hydro power page.

Tidal energy

This is another form of hydro energy that uses twice-daily tidal currents to drive turbine generators. Although tidal flow unlike some other hydro energy sources isn’t constant, it is highly predictable and can therefore compensate for the periods when the tide current is low. Find out more by visiting our marine energy page.

Geothermal energy

By harnessing the natural heat below the earth’s surface, geothermal energy can be used to heat homes directly or to generate electricity. Although it harnesses a power directly below our feet, geothermal energy is of negligible importance in the UK compared to countries such as Iceland, where geothermal heat is much more freely available.

Biomass energy

This is the conversion of solid fuel made from plant materials into electricity. Although fundamentally, biomass involves burning organic materials to produce electricity, this is not burning wood, and nowadays this is a much cleaner, more energy-efficient process. By converting agricultural, industrial and domestic waste into solid, liquid and gas fuel, biomass generates power at a much lower economical and environmental cost.

How to choose the best renewable energy supply for your business

There’s no denying it, time to tackle the climate crisis is running out and people want action! Companies are rushing to cut carbon emissions and switch to renewable energy. But it’s not like flicking a switch. 

There’s a surprising number of factors to weigh up as you choose the renewable energy sourcing strategy that’s best for your business. 

Confused? Start by watching this 4 minute video.


Got a question?

If you have a question about one of the topics in our TalkPower Energy Academy, or anything realted to the energy industry, ask our team of experts. 


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