Pyrolysis' Climate Credentials

Carbon removal
Pyrolysis' Climate Credentials

Project successes


Seb Megson, Sustainability Consultant at Onnu

Pyrolysis' Climate Credentials

Pyrolysis and its accompanying products have a wide variety of positive impacts on both the environment and particular social governance goals. Some are much more obvious than others, which means it’s important to understand exactly how the use of this new technology can make positive impacts both ecologically and commercially.

Green energy

Pyrolysis is a form of renewable energy that uses either waste products (biogenic and non-biogenic) or purpose-grown crops. This takes potentially landfill-destined waste, and gives it a second life producing clean and sustainable energy. Even if purpose-grown energy crops are utilised, this still takes polluting fossil fuels out of the equation. These fuels accounted for over 30 billion tonnes of carbon emissions in 2021

Why should we divert this waste?

There are many destinations for waste, most notoriously landfill. Over 12 million tonnes of municipal waste ended up in landfill in 2020, that’s almost as much as all the wheat grown in the UK in the same year.

All organic material in landfill undergoes a process called anaerobic digestion. This means that due to the lack of oxygen at these sites, this waste releases methane, a GHG roughly 25 times more climate damaging than CO2. Landfills are also notorious for damaging groundwater health through the percolation of the aptly-named landfill leachate, therefore damaging not just the global climate, but also local ecosystems.

Pyrolysis does however face some competition from other forms of energy generation which utilise this waste, most notably incineration.

This makes pyrolysis net carbon negative, and therefore has a positive impact on the climate and reduces a users carbon footprint

How does pyrolysis compare to waste-to-energy?

While on the surface pyrolysis and incineration may seem similar, they are in fact very different forms of energy generation. Unlike pyrolysis, the energy produced through incineration is not generated in a carbon negative way, as when it is burned with oxygen, the carbon dioxide that the plants absorbed from the air during their life is returned. Measures to minimise CO2 emissions at waste-to-energy plants are welcome of course, but while it may be a better waste management system than landfill or decay, it still does not actively remove carbon.

There are also technical factors which favour the use of pyrolysis.

  • Pyrolysis has a higher energy recovery efficiency than incineration.
  • Incineration emits high levels of heavy metals (lead and mercury), particulate matter and dioxins. These all contribute to significant health impacts such as increased rates of lung and neurological diseases, as well as cancer.
  • Incineration is less economically viable, while also taking up much more space than pyrolysis.
  • Pyrolysis produces products such as biochar, bio-oil and synthesis gas, whereas incineration does not.

How else does it help the environment?

The big one here is carbon sequestration, a term you’ll see a lot in our blogs. This refers to the process in which carbon is removed from the atmosphere through its capture in produced biochar. This makes pyrolysis net carbon negative, and therefore has a positive impact on the climate and reduces a users carbon footprint. Not something that can be said for many energy generation techniques. 

Through the use of biomass as a feedstock, biochar is created, which is a very effective soil additive. This can be used in lieu of chemical fertilisers to improve soil health and reduce surface runoff of these nasty chemicals, thus improving the health of both soil and aquatic ecosystems. The extremely porous structure of biochar increases water-holding capacity and therefore reduces necessary water usage.

Sustainable Development Goals (SDGs)

The United Nations sustainable development goals are a group of 17 targets which lay down the framework for achieving a sustainable and equal future for all.

Whether you are an energy user, feedstock supplier, biochar customer or have bought carbon credits, the involvement with the circular economy of the pyrolysis process contributes to 6 of the 17 goals.

  • 2 End hunger, achieve food security and improved nutrition and promote sustainable agriculture: Achieved through using biochar to implement more productive agriculture practices, while helping to maintain the health of local ecosystems.  
  • 7 Affordable and Clean Energy: This is done through the economically efficient nature of the pyrolysis process, while also providing clean and renewable energy.
  • 9 Industry Innovation and Infrastructure: This is achieved due to pyrolysis being a relatively new, sustainable and innovative technology, while fostering independent producers in the agriculture and manufacturing industries.
  • 11 Sustainable Cities and Communities: This is done by fostering sustainable waste management techniques in local communities as well as taking special care with air quality.
  • 12 Responsible Consumption and Production: This again is closely linked with sustainable waste management and procurement techniques of products and natural resources.
  • 13 Climate Action: Finally, this is achieved by the sequestration of carbon through the production of biochar.
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