A Guide to Biomass Power Plants

Biomass fuel is one of the most discussed alternatives in our rush to find an alternative to coal and gas. Many people across the world have started using it as an alternative to traditional fuels for heating their homes.

Biomass is even being used to fuel power plants – but what exactly is it? Why are power plants using it as fuel? Is biomass really a clean fuel?

We’ll answer all of this below, so read on to find out more.

What is a biomass power plant?

Unlike power plants that run on traditional fuels such as coal or gas, a biomass power plant runs entirely on, well, biomass. Biomass is a renewable organic resource that comes from plants and animal waste, and we can use it as fuel (including in boilers for homes).

When biomass power plants burn fuel, they create steam that turns turbines to generate electricity. This is very similar to how coal or gas-fuelled power plants generate electricity, with the main difference being the fuel used.

Burning biomass as fuel isn’t the only way to generate electricity with it. Other methods, such as gasification, treat the biomass differently to create power. During gasification, the biomass is heated with less oxygen than is needed in proper combustion. This produces hydrogen, which can then be used as fuel in the power plant.

The majority of biomass power plants use combustion to create energy, which creates the task of ensuring the combustion is as clean as possible.

How many biomass power plants are there in the UK?

Right now, there are 78 power plants using biomass to generate electricity in the UK. These 78 power plants have an estimated power output of 4,158 megawatts, which is enough to power around 8.3 million homes for an hour.

These biomass power plants include Ironbridge power plant, the largest in the world with a capacity of 740 megawatts, and Ferrybridge, which has a capacity of around 79 megawatts.

Are biomass power plants popular around the world?

As the world moves towards more sustainable methods of generating electricity, biomass power plants have definitely increased in popularity. Just over 10 years ago, there were around 2,000 biomass power plants, generating roughly 22 GWel (gigawatt electrical)* of electricity.

Now, in 2022, there are more than 4,500 biomass power plants, with a combined output of 74.6 GWel. This is still some way off the number of coal power plants in the world (8,500 as of 2021), but the signs are there that biomass power plants are quickly catching up.

*Gigawatt electrical (GWel) is a term used exclusively when talking about the electrical output of a power plant. It has essentially the same meaning as gigawatts per hour.

Are biomass power plants eco-friendly?

Using a biomass boiler is (usually) more eco-friendly than burning coal in power plants. Per kilowatt hour, biomass produces 230 grams of carbon dioxide – compare this to the 1,100 grams of carbon dioxide produced by burning coal, and the difference is clear.

But at the end of the day, the majority of biomass power plants still burn biomass, which releases pollutants into the atmosphere.

So no matter how often biomass is touted as a green alternative to traditional fossil fuels, it’s still a carbon emitter, even if these emissions aren’t quite as bad. On average, biomass produces around 80% less carbon emissions than coal, and around 50% less than gas (which emits 412 grams of CO2 per kilowatt hour).

There are outliers though, which we imagine some of the big biomass power plant owners would want to keep hidden. One government study into biomass fuel emissions revealed that biomass carbon emissions can actually be higher than either coal or gas emissions.

This is because biomass is sometimes imported, a process that comes with all the carbon emissions you’d expect from maritime shipping or other forms of transport. One well-known example of this comes from the Drax biomass power plant in North Yorkshire.

The plant made a bold claim in 2019 that, with the help of biomass fuel, it was to become the world’s first ‘carbon neutral’ business – meaning it would take in more carbon than it emitted. This was quite the claim for a power plant that once guzzled mountains of coal before converting to biomass.

Campaigners from various green groups (including Greenpeace and Friends of the Earth) opposed this, expressing their concern that the need for biomass would devastate forests and impact biodiversity.

Drax purchased Canadian wood pellet company Pinnacle Renewable Energy in 2021, clearly ignoring the campaigners’ concerns. It’s hard to imagine exactly how Drax will reach its prophesied carbon-negative status if around half of all the biomass it burns has to travel 3,600+ miles to get here.

One 2019 study on the impact of imported wood pellets showed the ridiculous levels of carbon emissions involved. 13-16 million tonnes of CO2 were emitted throughout the whole process of sourcing, transporting, and burning wood pellets imported from the US, which is equivalent to the annual emissions of 6-7 million passenger vehicles driving typical distances daily.

What advantages do biomass power plants have over other renewables?

Biomass power plants have a key advantage over other renewable energy sources: they don’t rely on intermittent power. Whereas wind power requires wind in order to work, biomass power plants simply use more biomass to keep the electricity flowing.

Solar power operates similarly to wind power, even when paired with a solar battery. Once the sun’s gone, it either doesn’t work at all, or it relies on what energy was stored in the solar battery during the day.

Basically, biomass power plants have what’s called reliable dispatchability, meaning that the electricity they generate is controllable and fully available on demand. You could argue this is what’s made biomass an increasingly popular choice for countries looking to clean up their carbon emissions.

You can find out more in our helpful guide: The Advantages and Disadvantages of Biomass Energy.

How much power do biomass power plants produce?

Biomass power plants have a capacity of between 2–1,000 megawatts (MW), though most range from 20 MW to 200 MW.

There isn’t actually a biomass power plant that has reached 1,000 MW yet – this is just an estimate of what a larger plant would be capable of.

The UK is not too far off that already – in fact, the Ironbridge power plant in the Severn Gorge is by far the biggest biomass power plant anywhere in the world. It clocks in at a staggering 740 MW, eclipsing the second largest biomass power plant (Alholmenskraft in Finland, with a 265 MW output capacity).

Do we expect more biomass power plants in the future?

Many countries are convinced of the merits of biomass power plants, even if green campaigners aren’t entirely sure it’s the right option.

On top of the existing 4,500 or so plants around the world, it’s estimated that a further 1,000 are already in the works.

Summary

There’s no two ways about it: biomass power plants are here to stay and, we suspect, eventually take over traditional gas and coal power stations. Biomass is cleaner than both gas and coal, but only when managed properly.

For instance, importing wood pellets from Canada to the UK is a great example of how not to be sustainable when it comes to biomass. The main question then is how to sustainably (and consistently) provide biomass power plants with locally sourced fuel. We must also figure out how to continue improving the efficiency of biomass power plants to reduce the emissions they currently produce – even if they are usually far lower than the emissions of power plants using fossil fuels.