Specifier Review

Bio-oil vs biomass

Dick Stephens, from Euroheat, explains why bio-oil should be used with caution and why, in many instances, wood is a better solution.

What’s bio-oil made of?

Some is recycled from waste oil (such as that used for cooking), but much of it is taken from plants which involves cutting down vast swathes of rainforest, killing the natural flora and fauna that should be in residence. Vegetable oil, which once was a more sustainable and cost effective option, has become increasingly expensive due to rising populations and rising food costs. Eating it is more useful than burning it.

To get it to a form that can be burnt requires a great deal of processing, which has its own carbon footprint. Bio-oil’s hydrocarbon train is chemically different to oil and must be processed correctly and burnt at a high temperature to prevent harmful dioxins being released into the atmosphere.

How is it burnt?

As mentioned, bio-oil requires high temperatures for ignition (much higher than wood or crude oil). For the purposes of an oil boiler, bio-oil can only make up 30% of the fuel, any more than that and it just won’t light properly. We’ve done extensive tests on bio oil and had to set up two fuel tanks to conduct out experiments, one purely for ignition purposes – once it gets up to temperature it burns fine, but on its own, it is not a practical fuel.

Better with biomass

While obviously not a solution for every home or business, if wood is a viable option, then in nearly all cases it is a better one than bio-oil. As long as it’s sourced from sustainable woodland, or, ideally, timber that would have been sent to landfill, it is a truly ‘green’ fuel. From tree to boiler is a simple process, even pellets have minimal engineering. We advocate being as natural as possible, with logs and chips air dried, rather than through any man made heat.

Apart from its environmental credentials, there’s a massive cost issue. Let’s look at the maths: We measure energy in kWh – one unit of electricity will keep a 1 kW device running for an hour, hence the heat energy delivered is 1 kWh. A litre of domestic heating oil would deliver around 8.5 kWh at a price of 7.6 pence per kWh. Logs equate to between 1 and 2 pence per kWh when you buy timber in bulk, so they can be less than a quarter of the price of oil – a considerable saving.

Logs are the cheapest wood-based fuel, but chips and pellets still cost a lot less – chips at 2.5 – 3.5 p/kWh and pellets at 4-5 p/kWh. These figures don’t even touch on the Renewable Heat Incentive which is already proving lucrative for commercial biomass users.

I’m not saying bio-oil is never a good choice – for businesses that create waste oil (such as food manufacturers and restaurants), they may as well use it. And, for existing crude oil customers switching to a bio-oil mix is undoubtedly a simpler fix and still better than doing nothing when it comes to cutting carbon. A word of caution, using bio-oil in an existing boiler may contravene its warranty, so check with the manufacturer first.”

For more information, about Euroheat, visit: www.euroheat.co.uk.

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