Your guide to biomass energy and how it works

With renewable energy sources in high demand, we look into the different types in more detail to find out how biomass energy works.

Disclaimer: The information on this page was last updated on 23/12/2022, 13:08:42

With renewable energy on the rise, you might be wondering how it all works. Biomass energy generates heat and energy through organic matter, whether that’s waste products or specifically grown for feedstock for fuel. Harnessing bioenergy has been happening successfully for thousands of years and was our main source of power until fossil fuels came along.

How does biomass energy work?

Biomass energy is the use of living or once-living materials as an energy source. This could be heat, electricity, or even biofuels.

Most biomass is made from plants and trees which means that being able to generate electricity depends massively on photosynthesis. During photosynthesis, plants are able to absorb energy from the sunny converting carbon dioxide into carbohydrates. When these plants are burned in a biomass plant, they turn back into carbon dioxide and water, releasing the energy they’ve stored, which we can harness and use as a fuel source.

When these biomass products are burned, the chemical energy is released as heat. We use this to heat water and use the steam to rotate a turbine (just like with a wind turbine). This spinning turbine sends kinetic energy to a generator, which can convert it into Direct Current (DC) electricity. Because our homes are powered using Alternating Current (AC) electricity, the DC electricity has to run through an inverter to convert it into useable power.

When biomass products such as food waste and sewage are left in sealed tanks to rot, they produce biomethane gas. This gas can then either be burned to generate electricity like other biomass products, or it can be fed into the national grid as a gas supply.

Is bioenergy good for the environment?

There is a lot of debate whether or not bioenergy is actually a renewable energy source, or if it’s good for the environment. Because burning the products produces carbon dioxide and leaving them to rot produces methane, some worry that bioenergy might leave us worse off. However, that’s not the case.

When plants are burned, while they release carbon dioxide, it was already in the air and was absorbed while they were growing, making sure that the carbon balance isn’t altered. Because most biomass products are grown specifically to be used as fuel, they’re continuously replenished with crops to reabsorb the carbon dioxide given off in the process.

When the waste is left to rot, they produce biomethane gas. Methane is one of the greenhouse gases we’re trying to eliminate, so how can this be good? When the waste is rotting, it’s left in sealed tanks which means that it can be captured and burnt to release carbon dioxide and water rather than harmful gases and pollution.

Advantages of biomass energy

People have been using biomass energy throughout history as an energy supply. Even something as simple as a wood-burning fire is a biomass heat source. It’s worked for us for centuries and has a range of benefits.

  • It decreases the need for large landfills – A lot of the waste we throw away can be burned to create energy and biomethane gas. Whether that’s food waste, paper, grass cuttings, or something else, it can all be made into energy.
  • No harmful emissions – While we’re trying to cut down on carbon emissions, the carbon dioxide released by burning biomass is quickly reabsorbed by other plants in the photosynthesis process, making it carbon neutral. The only greenhouse gas produced is methane, which is captured and burnt easily.
  • It’s sustainable – There are so many different organisms available to use as biomass fuel, from wood scraps to manure, we’re constantly creating new sources.
  • It can be used as both gas and electricity supplies – Electricity is generated from biomass using steam and turbines. On top of this, the natural biomethane gas created by the rotting bioproducts can be used as a gas supply.
  • It can create different products – Depending on the crops burned, different substances are formed. For example, corn can be burned to create ethanol which can be used to power cars or make alcoholic drinks.
  • It’s more profitable – As the technology costs a lot less than that of fossil fuels, meaning that manufacturers see higher profits.
  • Renewable Heat Incentive – By installing a biomass boiler, not only can you reduce your carbon emissions, but you can also receive payments from the Renewable Heat Incentive to help repay the investment.

Disadvantages of biomass energy

With such a great reputation as a power source, why would we move away from biomass?

  • It’s not completely clean – Burning wood still releases other emissions as well as carbon. While they’re not as harmful, they can still affect the environment.
  • It can be quite expensive – Compared to other forms of renewable energy, it’s the more expensive option both to set up and maintain.
  • Biomass plants take up a lot of space – There might not always be space available for biomass growth or power plants. Where there is space is often further away from cities and populated areas which need to use the power.
  • It’s inefficient – The main reason we moved towards fossil fuels is that they’re more efficient than biomass. Sometimes they’re even mixed in with biofuels to improve efficiency.

Heating your home with a biomass boiler

Biomass boilers are very similar to conventional gas boilers to provide heating and hot water. Instead of gas or oil, they burn various different wood types as fuel, such as wood pellets, logs, and wood chips. Some biomass boilers come with automatic feeders, meaning the wood pellets will be automatically fed into the boiler when they’re needed so you don’t need to worry about keeping it stocked up as much.

How much does a biomass boiler cost?

Compared to others, biomass boilers have a high installation cost. The average domestic wood-pellet fired biomass boiler costs around £15,000 to buy compared to a £2,000 oil-fired or £4,000 gas-fired boiler.

Despite these high costs, there are several different Government schemes which could help fund your new boiler. For example, the Green Homes Grant, which could help fund the upfront cost and the Renewable Heat Incentive, where you can receive payment for the energy you produce. With these schemes, you could see a payback time of as little as 5 years.

See what you could save by switching to a biomass boiler:

Fuel type Approx. running costs per year Carbon emissions per year
Coal £1,499 13,541kg
Oil £1,669 9,219kg
Natural gas £999 6,406kg
Electricity sourced from fossil fuels £2,690 10,184kg
LPG £1,920 7,663kg
Wood pellets £869 766kg
Wood chips £895 550kg

Bioenergy around the world

Modern bioenergy is a crucial source of renewable energy – it accounts for roughly one-tenth of the world’s primary energy supply. In 2019, biomass capacity around the world reached 123.8GW and it’s set to increase by 10% every year.

The majority of biomass capacity is in China, generating over 16.5GW. Straw and crop residue is burned and used primarily for heating and cooking. Agricultural, forestry, and garden waste are used for energy production and is taking an increasingly significant role in the country’s fuel mix.

Germany has the highest biomass capacity in Europe, generating almost 10GW and making up 87.3% of its renewable energy sources. They are currently investing most of their biogas to use to fuel vehicles, which is their top priority in cutting down carbon emissions.

Bioenergy in the UK

The UK has a biomass capacity of 7GW, generated in roughly 200 biomass plants. Surprisingly, the UK’s main source of fuel for its biomass plants is chicken manure, followed by other agricultural waste.

Bioenergy is a huge part of the UK’s fuel mix, averaging a share of 14.7% of all of our energy use.

Bioenergy for business

Switching your business to a renewable energy source is not only good for the environment but also a great way to improve your business practices and profitability.

Unlike other renewable energy sources, bioenergy can easily cut your waste management costs. Sometimes, you can’t cut down on the waste produced, however, now you can use that waste to power your workspace instead of sending it to landfill. Having your own energy source can be extremely cost-effective and can pay for itself quickly if you have the space for a biomass plant.

In the modern world, consumers are more aware of the environmental impact of businesses – just 100 firms are behind 71% of all greenhouse gases in the atmosphere. By generating your own energy on-site, this can be a great marketing tool to encourage more eco-friendly customers to shoes your company over your competitors.

There are several different Government-led schemes and initiatives that could fund your new biomass energy source or pay you for using your own biomass energy. This could be an extra form of revenue for your business, increasing profitability and return on investment.

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