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We’ve secured a patent for our method of converting knotweed waste into biochar

We’ve secured a patent for our method of converting knotweed waste into biochar


For some time, our R&D team have been working hard to develop an environmentally friendly way of dealing with Japanese knotweed waste, and now we’re excited to announce that our method of converting excavated knotweed into biochar has been patented.

We’re able to harness the extraordinary CO2 scavenging powers of Japanese knotweed in the fight against climate change by heating knotweed plant material in the absence of oxygen, a process known as pyrolysis, thereby removing naturally occurring tars to leave carbon in the form of charcoal. The charcoal, which benefits from a honeycomb-like structure, can then be charged with additives such as liquid organic fertilisers, to create a soil amendment that improves soil structure and locks carbon away in the soil for hundreds if not thousands of years.

The Japanese knotweed removal industry generates thousands of tonnes of plant waste every year which is consigned to landfill sites where it either regrows, or decays giving off landfill gases such as methane. This is both expensive and environmentally harmful. As knotweed continues to spread across the UK, now affecting 4-5% of households, a more environmentally friendly solution is urgently required to dispose of this plant waste.

Granted a patent this month, our method could potentially be used to deal with all the UK’s Japanese knotweed waste and that produced by other invasive plants such as bamboo and Giant Hogweed. We already use a unique eco-friendly excavation method, Xtract™, which sifts infested soil to remove knotweed rhizome before returning the cleaned soil to the ground. Conversion of the remaining rhizome to biochar is the final stage of a completely eco-friendly solution for dealing with Japanese knotweed waste.

Environet Founder and MD Nic Seal said: “I’ve been looking for an eco-solution for the Japanese knotweed rhizome we remove from the ground for many years and after a great deal of research, I’m pleased to say we have now successfully developed a method that not only eliminates the need for landfill but captures all the carbon collected by the plant during its lifetime and locks it away. Japanese knotweed may be the villain of the plant world, but for the first time it has the potential to do some good!”

The next stage of our research will tackle delivering economies of scale, including how to process large quantities of knotweed waste quickly and efficiently, managing emissions produced by the pyrolysis process – and sourcing markets in the agricultural and horticultural sectors for the biochar produced.

We hope to be converting all our excavated plant waste to biochar by the end of 2022, as part of our pledge to become a carbon neutral business. Watch this space!

If you have a subscription, you can read all about this story in our exclusive with The Telegraph.

Robert Spaceman

“We had a large stand of bamboo removed, thinned, contained and replaced. The customer service has been first class. Joe and Jason were fabulous and kept me well informed at all times”.