Powerchip: 20-100kW Biomass Boilers

Passing small logs or wood waste through a chipping machine produces 3mm pieces (also known as G30). Find out more here.

Approximately 3.5 kWh per kg, depending on the moisture content of the chips. We recommend a maximum of 30% moisture and you can check this with a moisture meter.

Wood chips need approximately three times as much storage space as wood pellets;

• Wood Chips = 250KG/m3
• Wood Pellets = 650KG/m3

We always recommend using the fantastic Biomass Suppliers’ List (BSL) for a comprehensive list of high quality suppliers across the UK.

If you get bought-in wood chips, you can expect to pay £120 per tonne. Alternatively, if you have your own wood supply, you can arrange for contract chipping for around £50 a time. Contract chippers charge about £150 per hour and they can chip around 15 tonnes in an hour. So you can potentially chip your entire annual supply in half a day and load it straight into your fuel store.

Wood pellets are made from compacted sawdust or any other waste produced from sawmills and other manufacturers.

It’s 4.8kWh per kg, meaning you only need one third of the storage space that you would need for chips. Plus you get three times as much heat.

• Wood Chips = 250KG/m3
• Wood Pellets = 650KG/m3

1 litre of oil is equivalent to 2kg of wood pellets.

You can expect to pay between £180 - £220 per tonne.

We always recommend using the fantastic Biomass Suppliers’ List (BSL) for a comprehensive list of high quality suppliers across the UK.

The pellets will need to be ENPlus A1 or A2. These are 10-12mm long and 6mm in diameter. Your wood pellets need to be dry, clean, mechanically robust and possess an ash content defined by appropriate standards. They need to be able to flow freely and delivered via a pneumatic system. Check out this handbook from HETAS for more information about wood pellets.

Absolutely. Grain is an economical and convenient fuel for biomass boilers. Pourable options like oats, barley and wheat have a low nitrogen content and can be used in models such as Guntamatic’s Powerchip and Powercorn boilers.

It really depends on the grain: barley gives 4.3-4.4 kWh per kg and wheat gives 4.5-4.6 kWh per kg. Grain is slightly denser than Miscanthus, so will need less storage space.

We advise adding around 0.3 – 0.5% by weight of slaked lime (calcium hydroxide Ca(OH)2) to your fuel before using it in boilers with ratings up to 50 kW and 0.5 – 0.8% for boilers with ratings over 50 kW. This increases the calcium content of your fuel and raises the ash fusion point. This reduces the amount of clinker that can form.

Keep moisture content less than 13% to avoid wasting energy on burning off excess moisture. This will ensure your boiler is as efficient as possible.

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.

Miscanthus 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.

The Guntamatic Powercorn and Powerchip models will both burn Miscanthus (in chopped or pelleted form). To ask about other models, please get in touch.

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.

We advise adding around 0.3 – 0.5% by weight of slaked lime (calcium hydroxide Ca(OH)2) to your fuel before using it in boilers with ratings up to 50 kW and 0.5 – 0.8% for boilers with ratings over 50 kW. This increases the calcium content of your fuel and raises the ash fusion point. This reduces the amount of clinker that can form.