Miscanthus

Also known as ‘elephant grass’, Miscanthus is a perennial grass which grows and spreads quickly, even on land of poor quality. It’s so easy to cultivate and requires little to no intervention. This is why it’s such a popular option for biofuel. 

It has a calorific value of 3.6-4 kWh per kilogram and weighs 70-90 kilograms per metre cubed. It’s less dense than grain and therefore you’ll need more storage space. 

It’s imperative that Miscanthus is kept dry and ventilated to get the best out of it. Its moisture content cannot be above 20% and it must conform to W20 standards for chopped, air-dried Miscanthus and W30 for storing and drying. 

As with grains, Miscanthus ash has a tendency to bind together - or ‘clinker’ - at heats 900° (compared to 1,200°C for wood ash) but Guntamatic have anticipated this with the Powercorn and Powerchip models, which feature a moving, self-cleaning grate to reduce clinkering.

It’s advised to up the calcium content of your Miscanthus by adding 0.3-0.5% (by weight) of slaked lime to boilers up to 50 kW and 0.5-0.8% for boilers rated over 50 kW. This can help to increase the fusion point of ash and reduce the chances of ash binding together. 

The table below highlights how well Miscanthus performs up against other fuels.