A positive outlook on changes to the RHI

Hoval, biomass, renewable energy, boiler
A strong market for biomass heating — Adrian Walker

Changes to the Renewable Heat Incentive (RHI) aren’t necessarily as negative for biomass heating as many people think and could even broaden its benefits — as Adrian Walker explains.

In October 2011 the Department of Energy & Climate Change (DECC) announced changes to the tariff structure of the Renewable Heat Incentive (RHI) in relation to large (greater than 1 MW) biomass projects. This announcement followed concerns expressed by the European Commission that the tariffs were too high.

The previous tariff for such large installations was 2.7 p/kWh, and the Government reacted quickly to respond to the European Commission’s concerns and reduced the tariff to 1 p/kWh. The swift action made it possible for the Department of Energy & Climate Change to issue an announcement on 25 November that the Renewable Heat Incentive, the world’s first, would be ‘open for business’ on 28 November.

The initial reaction of many to this announcement was that it would threaten the uptake of biomass heating and the carbon-reduction benefits that will undoubtedly accompany wider biomass usage. In contrast, I believe this may result in a better spread of the incentive — with more smaller users benefiting, rather than the benefits being concentrated on a few large users.

Nor do I think that the tariff change will deter larger projects from including biomass in their mix of heat sources. It will simply mean that the base loads for biomass will be less than 1 MW. Given that the most efficient way to use biomass in most cases is for meeting the base heating load through the year — or for domestic hot water when return temperatures are too high for condensing — this is probably about right for many sites.

So, in my opinion, there is a good chance that these changes to RHI tariffs will actually encourage a better solution that is based on sound engineering principles rather than what is fashionable or good for the image. Such systems will typically use a balanced mix of heat sources that takes full advantage of the performance characteristics of each technology. For instance, where biomass is used to meet base heating loads, gas-fired boilers may provide a highly efficient way of responding to peaks in heating demand. There may also be opportunities to include other heat sources such as solar thermal and heat pumps — as long as the controls are configured to optimise the use of each.

Beyond the RHI

It is also worth noting that, while the RHI is in the spotlight at the moment, it is not the only reason for using biomass. Many projects had already incorporated this heat source before the RHI was announced because biomass heating offers major benefits in its own right.

Not least of these benefits is that biomass is virtually carbon-neutral as the carbon emitted by burning biomass fuels was captured just a few years earlier when those plants were growing and will be reabsorbed by plants grown for future supply. In contrast, the carbon in fossil fuels was fixed over millions of years but is being released into the atmosphere in the space of just a few hundred years, altering the balance of the carbon cycle.

This means that the carbon emissions associated with biomass fuels are largely restricted to the harvesting and transportation of the fuel. Indeed, the better biomass fuel suppliers have already taken other carbon-reduction measures to compensate for this and produce a ‘close-to’ carbon-neutral fuel.

Hoval, biomass, renewable energy, boiler
Biomass boilers are well suited to centralised energy centres, where it is easier and more cost effective to meet the fuel-handling requirements for wood pellets or wood chips.

Furthermore, biomass boilers are relatively easy to retrofit to existing heating systems to help reduce their carbon footprint as they deliver the same flow temperature (82°C) as traditional gas- and oil-fired boilers. This eliminates the need to replace heat emitters in the building to allow for lower flow temperatures, as is often the case with other low-carbon heating technologies.

It is also worth noting that around 90% of the UK’s sustainable wood-pellet production is currently exported, so there is plenty of spare capacity to serve a growing UK biomass heat market with a secure fuel supply. And, of course, using locally produced fuel reduces the carbon footprint associated with transportation — as does using a biomass boiler made in the UK.

Energy centres

Another factor that supports the wider use of biomass is the growing trend for centralised energy centres with district-heating systems serving individual buildings or dwellings. This strategy is now being applied to even relatively small projects such as housing developments and retail parks.

In these cases, base heating loads through the year may be met by a CHP unit sized on its thermal output, supplemented by biomass heating to accommodate higher base loads in cold weather and condensing boilers to respond to peaks in heating demand. Centralising plant in a dedicated energy centre makes it easier and more cost-effective to meet the storage requirements for the wood pellet or wood chip biomass fuels.

For all of these reasons I believe there is still a strong market for biomass heating in the UK. I also suspect that the changes to the RHI will actively encourage greater emphasis on the skills of building-services engineers, resulting in better engineered and more efficient heating systems that deliver real environmental benefits.

Adrian Walker is managing director of Hoval.

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