Burning issues

It’s a chilly day in northern Scotland, and Michael White is lifting a 15kg sack and pouring pellets made from sawdust into the top of his biomass boiler, located in an outside room.

The White family live in Findhorn eco-village, Inverness-shire, and share their 25kW boiler with two other households. “We all wanted to lower carbon emissions and by sharing a system, it became even more environmentally sound,” says White, before inviting me to see their south-facing upstairs living area with its 4m-high ceilings. The boiler, he says, keeps them warm inside, even in the bleakest drizzly weather – what the Scottish call “dreich”.

According to the Department of Energy and Climate Change, a mere 1 per cent or so of UK households use non-fossil fuel, or “renewable” heating. About 80 per cent of British domestic heating is provided by 18-20m gas boilers. The remaining 2m homes are off-grid, mostly relying on heating oil or liquefied petroleum gas (LPG). Heating accounts for almost half of all Britain’s fossil fuel use (and its carbon emissions) and 55 per cent of that is for homes, the department says.

The Whites and their neighbours are a minority: homeowners who have chosen to forgo fossil fuels for environmental reasons rather than financial. When they installed their biomass boiler, with a small grant from the Scottish government, it cost £12,000 between the three households. Installing gas boilers in each house would have cost about one-third of that.

Britain is committed to using renewables for 15 per cent of its energy use by 2020. (This is not much. Sweden is already harnessing 44 per cent of its energy from renewables and is aiming to reach 60 per cent.) To help reach its target, after several delays, the UK government last month launched an incentive scheme that will, eventually, pay householders to produce heat from renewable sources. The renewable heat incentive (RHI) is meant to make up for additional costs incurred by changing to renewable heating. It is the first scheme of its kind in the world that subsidises by paying per unit of heat produced.

The aim is that by 2020, there will be a sevenfold increase in the amount of renewable heating and a saving of up to 44m tonnes of carbon. So, can we sit back by our (sustainably harvested) log fire, enjoy the glow of righteousness and count the money coming in? Unfortunately, it’s not that simple.

In phase one of the RHI, the non-domestic sector is being targeted, with tariffs paid from this July. If your home is a bed and breakfast or you share your renewable heating with other households in a “district heating” scheme, you could qualify for this phase. Installations dating from July 2009 are eligible. However, most homeowners will have to wait until next October to receive payments per kilowatt hour. As long as your house meets energy efficiency criteria and you employ an installer accredited by the microgeneration certification scheme, various domestic renewable heating systems will qualify: solar thermal, biomass boilers (burning organic matter) and heat pumps that extract and upgrade ambient heat. Simple wood burning stoves or fireplaces that can also burn coal may be cosy but aren’t efficient and do not qualify.

From this July, some 25,000 “premium payments” – one-off subsidies, expected to range from £300 to £1,250 – will be available. By making an investment upfront, renewable heating “is a bit like buying your fuel in advance”, says Howard Johns of the Solar Trade Association. “You can fix the cost of your energy.” This is truest in the case of solar-thermal.

Choosing a system to suit your needs can be daunting. As Stewart Purchase of heating consultancy 21 Seventy asks: “Do you want to invest in the planet or save money?”

If your aim is to “invest in the planet”, then solar thermal “comes with the least problematic issues”, says Doug Parr, scientific adviser for Greenpeace. However, unless you live in a perfectly designed eco-house (like that of architect John Christophers, whose converted Victorian terrace in Birmingham gets 92 per cent of its energy needs from the sun) it is unlikely that solar thermal will do more than heat hot water.

That’s why you will need some form of supplementary heating. A domestic biomass boiler can save up to 9.5 tonnes of carbon dioxide a year and nearly £400 in fuel if replacing coal or heating oil, according to the Energy Saving Trust.

However, if you are replacing a gas boiler, you may end up paying more in fuel, especially with the rising price for biomass (wood chips or pellets). There’s also the issue of sustainability. “If you’re getting wood from local, well-managed woodlands, then that’s fine,” says Parr. “What we don’t want to see is badly managed woodlands and old growth forests turned into woodchips for heating.”

The boilers need regular maintenance and storage space for fuel. They also emit particulate pollution. This could become a problem if biomass is adopted in a big way. One way to combat the deteriorating air quality that may result is to combine biomass with solar-thermal so that water is preheated. Such dual systems are increasingly common: in Denmark, a district heating scheme provides most of the heat for 1,400 households from solar-thermal. The remaining 45 per cent is from biomass.

As for heat pumps, which extract the sun’s heat stored in the ground or air, even in a cold climate – a study by the Energy Saving Trust found that well-designed and installed pumps could operate well in the UK. However, some homeowners found them complicated to operate. Generally, air-source heat pumps are less efficient than ground-source ones – although the latter need major excavation work. Some advise that you should only install a GSHP if you have to dig a hole anyway. Mark Aston, a green-building project manager trading as Mr Wolf, tells the salutary tale of striking a high-pressure water pipe while digging.


Renewable Energy Association, www.r-e-a.net

Micropower Council, www.micropower.co.uk

Energy Saving Trust, www.energysavingtrust.org.uk

Solar Trade Association, www.solartrade.org.uk

Department of Energy and Climate Change, www.decc.gov.uk

Heating consultancy 21 Seventy, www.21seventy.com

Ecomakeover consultant Mark Aston, www.mrwolfinc.com

Geothermal International, www.geothermalint.co.uk

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