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Low-Carbon Future: Is Biomass an Answer?

Biomass boiler fuel

Biomass boilers often feature in lists of renewable and low-carbon heating systems. But are they really as good for the environment as this suggests?

Burning biomass (wood in the case of biomass boilers) only releases the carbon that was absorbed by the tree as it grew. So, it's argued that by planting more trees, any carbon can be reabsorbed to make a carbon neutral cycle.

The problem is, it takes many years for trees to grow to a size where they've absorbed that much carbon. This means the carbon a biomass boiler releases today will be heating up the planet – not getting reabsorbed. Plus, burning biomass releases other pollutants into the air too.

So, just how green are biomass boilers?

What is biomass?

Biomass is biological material from plants or plant-based materials. When used as fuel in a biomass boiler, it takes the form of wood chips, pellets or logs.

It's a fuel that needs to be stored at the property – like oil or LPG – which means they take up a fair amount of space. The biomass boiler itself isn't exactly the most compact heating system either.

Isn't burning biomass carbon neutral?

Being carbon neutral means that any carbon you add into the atmosphere is cancelled out by taking measures to reabsorb this carbon.

You may have heard about companies planting trees to offset their carbon emissions. On the face of it, this is a great idea but it's not as simple as that.

To get fuel for a biomass boiler, large trees that have been growing for decades are cut down. They're then burned within a boiler, which releases carbon into the atmosphere. However, it's only the carbon that was absorbed by the tree (or plant) as it grew.

It's thought that if you plant another tree, it will absorb the carbon released by the tree used as fuel. But trees take years to fully grow (30 years at least) and will gradually absorb carbon over that time. Whereas the carbon released by your biomass boiler will contribute to climate change today.

Essentially, we're cutting down large trees to cater for biomass boilers and replacing them with much smaller younger trees. Depending on the type of tree it is, it will take at least 30 years to fully grow.

So, 'carbon neutral' is a bit of a stretch.

Is it better than burning fossil fuels?

On the face of it, burning biomass could be seen as a better option than burning fossil fuels. Which may well be the case. After all, when a gas or oil boiler burns through fuel, it's adding to the carbon levels in the atmosphere. Whereas burning biomass only releases carbon that has already been in the atmosphere (before it was absorbed by the tree).

Carbon isn't the only gas that's having an impact on the planet though and burning biomass releases various other toxins into the atmosphere. There's also:

  • Particulate Matter (PM): These are solid and liquid particles that can often be seen by the naked eye, such as soot and smoke.
  • Nitrogen Oxide (NOx): Formed during any combustion process (car engines, boilers etc.) and can be harmful to people and the planet.
  • Sulphur Dioxide (SO2): In large volumes, it can cause acid rain which, in turn, is harmful to trees and can lead to deforestation.
  • Other Hazardous Air Pollutants (HAPs): This is a collection of 187 toxins that the Environmental Protections Agency lists as "those known to cause cancer and other serious health impacts".

If all of the above wasn't bad enough, should more people start heating their homes with biomass then demand for wood will soon overtake supply. And that will lead to deforestation.

We’re not suggesting that gas and oil boilers are innocent in all this. Burning those fossil fuels releases a list of harmful gases into the atmosphere too. As well as carbon, using these fuels to heat our homes also increases the levels of sulphur dioxide, methane and nitrous oxide in the atmosphere. This is why alternative low-carbon boiler fuels, such as hydrogen and green gas are being considered.

Are there any benefits to using biomass?

Knowing what we now know, there aren't too many benefits left for the biomass boiler.

As a homeowner with a biomass boiler you could look forward to low running costs – possibly even as low as zero if you live near a wooded area. Then, on top of that, you could be earning money through the Renewable Heat Incentive (a scheme designed to encourage more homeowners to turn to renewable heating). Although this initiative will be closing to new applicants at the end of March 2022, when it will be replaced by the Clean Home Grant.

One claim that can be made to support biomass boilers from an environmental point of view is that they can help to reduce landfill waste:

Millions of tons of waste wood is sent to landfill every month. When left to rot, it emits methane. This is a harmful greenhouse gas that has a warming power 80 times higher than carbon over its first 20 years in the atmosphere. In that sense, perhaps burning the wood for fuel is putting it to better use than sending it to landfill.

Explore the advantages and disadvantages of biomass boilers.

Alternative renewable heating systems

Biomass boilers aren't the only renewable heating system out there. So, if you're questioning the environmental credentials of a biomass boiler, you still have plenty of choice to find a way of heating your home that's kind on the environment:

  • Air source heat pumps: A fan draws in the air outside before the heat is captured and warmed further to give your home central heating. Many air source heat pumps can keep heating your home in sub-zero temperatures.
  • Ground source heat pumps: Underground temperatures are around 15°C all year. That heat is absorbed by a refrigerant circulated through underground pipes.
  • Solar thermal: Panels that absorb heat from the sun which can then be used to warm up the hot water in a cylinder.

Read more about these renewable heating systems in our guides to air source heat pumps, ground source heat pumps or solar thermal.

Talk to renewable installers near you

If you're looking for a renewable heating system, then you're in the right place. We have a network of renewable installers across the UK ready to quote on your job. All you have to do to get in touch with those in your area is complete our simple online form.

You'll then get free quotes for a renewable heating system from up to 3 installers. Once you've compared them, you'll know that you're getting the most competitive price from the best person for the job.

Adam

About the author

Adam

Adam is our resident home heating expert. His experience and advice has helped millions of customers improve the efficiency of their homes and save money.

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