Bale, pellet or multi-fuel? The different types of biomass boiler explained…

Commercial biomass boiler installation, NottinghamWe’re often asked to explain the difference between different types of biomass boilers, so we thought we’d take the time to explain a bit more here. There are three main types of biomass boiler: bale, pellet and multi-fuel, and as the names suggest, the difference lies in the type of solid fuel burned.

All three will cut your fuel costs compared to oil or LPG. And assuming the system is optimally designed to meet current RHI criteria, they’ll all earn you 8.6p per kilowatt of heat generated, which can add up to thousands of pounds every year, for 20 years. But which one’s best for you?

Bale-burning biomass boilers

Bale burning biomass boilerFor obvious reasons, bale-burning biomass systems can seem an attractive option for arable farm businesses and other rural applications where straw is in plentiful supply. If you can grow your own fuel, that has to be the most cost-effective source of energy, right?

Well, yes – but we’d never recommend a bale-burning biomass boiler. It’s true that they cost less to install and there’s no doubt that straw is a cheap source of energy, but they’re massively inefficient. The heat output from a bale burning boiler is much lower compared to other types of biomass system, they’re much more labour-intensive in terms of feeding and cleaning, and the ash generated means they’re far more prone to system failures. Indeed, many bale burners don’t last the 20-year term of the RHI scheme, which is bad news, because if you have to replace your biomass boiler mid-term, you also have to reapply for Renewable Heat Incentive payments at whatever tariff is applicable at the time of the new installation. The tariff is unlikely to go up, which means you’ll lose out.  It pays to fit the best from day one, which is why we like ETA boilers.

Pellet-fed biomass boilers

Biomass pelletsThe key advantage of a pellet-fed boiler is convenience. The fuel comes in the form of pellets, which are widely available and fed to the boiler from a hopper via an augur. If you’ve got the room, the hopper can itself be fed by a bulk pellet store. Pellet boilers are often referred to as a ‘fit and forget’ option because they largely take care of themselves, and they’re our recommended biomass solution for people with limited space – the pellets are quite compact so you don’t need bags of room for storage.

Multi-fuel biomass boilers

Miscanthus grass Multi-fuel biomass boilers give you the flexibility to burn pellets, woodchip or Miscanthus (not all at once – you have to clean the system each time you switch fuel). Because woodchip and Miscanthus are less compact than pellets, you need to set aside more room for fuel storage if you go for a multi-fuel system over pellet – but if you’ve got that space, this would be our ultimate recommendation.

What you lose in space, you more than gain by burning a cheaper fuel source. Each kilowatt of heat generated by a pellet boiler costs 4.8p. With a multi-fuel system, this comes down to 3.1p if you buy woodchip or burn Miscanthus – and don’t forget, you can burn pellets too.

Multi-fuel boilers are a particularly attractive option for agricultural applications – if you chip your own wood, your fuel costs come down to around 1.6p per kilowatt of heat.

We hope this quick guide has explained the main differences between the different types of biomass boiler – if you’d like to know more, call 0115 952 0263 or 07890 022002. We can give you some friendly advice over the phone and, if you like, come and assess your property for free and give you a quote on the best biomass option for you.