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It’s harvest time! How miscanthus is leading the way in bioenergy

March is a busy time at Carbon Trap HQ. We’re preparing for and starting the harvest of 800 hectares of miscanthus (elephant grass). The first harvest sees 20 hectares of rhizomes being lifted from the fields before being sorted by hand in the cold store. Then in the second week of March we get started on harvesting the 780 hectares of miscanthus cane.

But what are the miscanthus rhizomes and cane for? And why does it matter? Read on for an insight into our spring processes and how Carbon Trap are contributing to the 2050 carbon zero targets.

Miscanthus: the CO2 superhero

Miscanthus (or elephant grass) is a non-invasive perennial (grows back every year) bio-energy grass with superhero strength CO2-capturing abilities and multiple uses as a sustainable material for textiles, packaging and construction. We grow it at three sites across Somerset and Lincolnshire.

Miscanthus differs from other plants because it has the ability to take in very large amounts of CO2. It grows well when the weather is warm, and it starts to die off around the end of October when the nutrients go back into the rhizome ready for the next stage.

Rhizomes: the root that gives 20x the yield

Rhizomes are effectively the miscanthus root, its underground food store. They vary from the size of your thumb to the size of your hand. We use these rhizomes to propagate more miscanthus. From each hectare we lift, we can plant a further 20 hectares of miscanthus! The rhizomes remain in the soil over winter until they become dormant. This is when we begin our harvest, but not before some heavy prep work at our sites.

We recruit extra hands for this harvest and need to get our cold store ready for processing the rhizomes. For this, our machinery needs servicing and electrics need checking. The gas for our cold store has to be stored in an underground bunker over winter, so this needs to come out and the compressor filled so we can start the fridge again. Then we have a health and safety audit. Once we’re ready, the machines head out to the fields.

A rotor spike brings the rhizomes and soil up to the surface , these are then collected by a machine that shakes the soil away. The rhizomes and partial soil are collected and taken to the processing shed for the workers to sort the good from the bad. The good rhizomes will be propagated for next year’s miscanthus crop.

Is there anything miscanthus can’t do?

Next comes the big harvest: 780 hectares of miscanthus cane aged 2–25 years will soon be cut, baled, hauled and stacked in our cold store ready for its onward journey to one of 3 industries:

  • Sustainable packaging, textiles and construction (more on this another time)
  • Animal bedding – miscanthus makes a superb equine bedding!
  • Energy

Plant-powered energy

Did you know that 12% of UK’s electricity comes from biomass, e.g. straw, wood and miscanthus. Despite popular belief, our green energy doesn’t all come from solar panels and windmills.

Miscanthus forms 90% of the perennial energy crop group that is burned as waste for electricity at 4 biomass-fired power stations in the UK. Crop yield and animal bedding demands make wheat an erratic market, whereas miscanthus can be grown purely to contract. As such, miscanthus has become the preferred crop due to its high yield, high calorific content and reliability.

Whilst we would rather see our miscanthus be used for something other than burning (and this is something we’re working hard to create), we’re content for now that growing and burning miscanthus our way keeps the process carbon neutral because the equivalent CO(and more) that’s released up the chimney will be reabsorbed by next year’s crop.

Let the numbers speak for themselves

The Climate Change Committee have called for 30,000 hectares a year of miscanthus to be planted to reach 700,000 hectares of perennial energy crop by 2050. This will be equivalent to 10% of the 2050 carbon zero target. We think this is perfectly achievable! After a long battle we’re happy that the government are now regular visitors to Carbon Trap and see what amazing things miscanthus can do for our environment.

Miscanthus crops in the UK have done more to mitigate CO2 than solar panels and windmills fitted in the last 12 years.

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We’ll be back soon for an update on the harvest and Carbon Trap’s plans for the summer. If you want bite-sized updates delivered to your inbox, you can join our newsletter by entering your email address in the footer below.