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Rethinking biomass boilers

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Richard Waite investigates claims that issues involved in running a biomass boiler are driving schools to turn theirs off and architects to reconsider specifying them

‘There is still a case for biomass, but it isn’t a silver bullet,’ says Gary Clark, principal architect at Atkins.

The number of stories reaching the AJ about the shortcomings of biomass boilers is growing daily. Sources say a raft of schools are giving up on their maintenance-heavy wood-chip or pellet-fuelled boilers and are instead relying on back-up gas-fired boilers.

These problems first came to light back in 2005, when the biomass boiler installed at White Design’s Kingsmead Primary School in Cheshire continually overheated. Other schools haven’t even bothered to turn their biomass equipment on.

This does not seem to be deterring design teams working on the new wave of Building Schools for the Future schemes, 86 per cent of which are going down the biomass route. Garry Palmer, director of advanced design at AECOM, which has been carrying out detailed research into biomass boilers, understands why this is. ‘Biomass is almost certainly the cheapest in terms of capital cost, and is the easiest way to get the additional Department for Children, Schools and Families [DCSF] funding available for low-carbon schools.

‘The DCSF carbon calculator does kind of push you down the biomass route.’

‘However, when you look at lifecycle costs, other routes are more cost-effective… but the DCSF carbon calculator does kind of push you down the biomass route,’ adds Palmer.

Ben Humphries, an associate at Architype, has seen both sides of the biomass boom. ‘In non-urban areas where there is a good local source of biomass, these systems can work pretty well, such as in our St Luke’s Primary School in Wolverhampton (pictured)

‘But we had a scheme in Southwark that was a nightmare. Our client ended up waiting for two months for a pellet supply – in the end they had to come in from Northern Ireland. And that doesn’t really stack up.

‘The other big concern is the impact of having to create new biomass plantations that could displace agriculture, forcing food production overseas, effectively just shifting the carbon footprint overseas,’ adds Humphries.

Most architects agree biomass should be part of a package of renewables, rather than a catch-all solution. However, getting biomass boilers past the planners at all is becoming increasingly difficult. In November last year, City of Edinburgh Council issued a report ‘discouraging’ the approval of biomass installations due to potential health risks and their impact on local air quality.

Clark says: ‘Biomass within large-scale urban projects is a stopgap until we come up with a better solution… The rush to apply new technology should always be carefully considered and weighted against more simple passive measures.’

Ian Goodfellow, partner at Penoyre & Prasad, is concerned about the long-term issue of maintenance. ‘Achieving on-site renewables targets with expensive equipment that requires a lot of maintenance, like biomass, doesn’t make sense, and probably doesn’t save much real carbon.’

However, ZEDfactory founder Bill Dunster says: ‘Any school that bothered to understand the physics, complemented the biomass with solar thermal for summer use, and made the maintenance into a study project could easily run one with less time investment than keeping gerbils.’

Key points from City of Edinburgh Council’s policy on biomass boilers (Nov 2009)

‘Concerns have emerged… regarding potential impacts on human health from certain emissions associated with widespread uptake of wood biomass combustion.

‘These are described in the UK’s National Air Quality Strategy 2007 as “being consistently associated with respiratory and cardio-vascular illness and mortality, as well as other ill-health effects. It is not currently possible to discern a threshold concentration below which there are no effects on the whole population’s health”.

‘It is therefore proposed that the precautionary approach currently adopted by [the council] be continued… biomass installations… should be discouraged unless proven, cost-effective emissions abatement technologies become available.’

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Readers' comments (1)

  • Kingsmead - British engineering at its best.

    Its very important to specify the correct tried & tested equipment, Scandinavian & Austrian boilers have been used in excessive of 20 years and most have trained their UK agents to install and service their equipment successfully.

    The wood fuel supply chain has developed extensively over the past three years with pellet production capacity now 200,000 tonnes plus and growing by the year. Many public buildings and private house's are heating with pellets for as low as 3.5p/kWh, a good price especially if you are in an off gas area, all operating succesfully with top brand boilers from EU.

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