The growing use of renewable heat sources presents specifiers and installers with a number of challenges, says Adrian Walker, managing director of Hoval.
Over the last few years there has been steady growth in the use of renewable energy sources. At a building level, this has tended to focus on renewable heat sources such as biomass and solar thermal, as well as low carbon heating technologies like heat pumps.

The recent introduction of the Renewable Heat Incentive (RHI) is set to give a major boost to renewable heating. In the experience of
Adrian Walker, managing director of Hoval Ltd, biomass boilers are proving particularly popular for many projects.

This, he says, imposes certain challenges on specifiers and installers because most have far more experience of gas and oil fired heating plant than they have with solid fuel. 'As a result of the RHI, as well as the host of sustainability issues that building operators are addressing, it's clear many more building services specifiers and installers are going to be working with biomass heating plant,' suggests Mr Walker. 'While modern biomass boilers incorporate many of the sophisticated automation features you would expect from a gas or oil fired boiler, there are still key differences when it comes to using wood as the fuel,' he notes. 'This doesn't make it any harder to use biomass but those differences do impact on the design of the system, as well as associated criteria such as installation time, fuel storage etc.'

We asked what these key differences might be. 'There are a number of interrelated things that need to be considered, starting with an understanding of the performance of different biomass fuels,' Mr Walker continues.

Wood is main biomass fuel

'Wood is currently the predominant biomass fuel in the UK and seems set to remain that way. However, wood fuel may be supplied as wood chips or wood pellets and the combustion characteristics of these are very different.'

The combustion characteristics, he explains, influence the fuel storage volumes that will be required and the frequency of fuel deliveries and, in turn, the nature of the delivery vehicles that visit the site. Wood chips tend to be delivered by tipper lorry directly into an underground storage area, whereas pellets can be delivered by a smaller blower lorry into an outdoor or indoor silo. So it's also necessary to consider issues such as access for delivery vehicles when designing the system.

'In addition to these considerations, the physical characteristics of the different fuels have a bearing on the types of storage facility and the mechanisms required to feed the fuel to the boiler,' warns Mr Walker. 'So this needs to be factored into the design and project costings as well.

'For all of these reasons I would suggest there is a strong imperative for anyone involved in the specification or installation of biomass systems to familiarise themselves with biomass heat engineering - and there are training courses to help them do that.

'Not only will such training enable to them to assess the viability of biomass for different projects, it will also help them to ensure they optimise system efficiency for the end client.

'As well as providing training, manufacturers like ourselves can also help specifiers and installers in other ways. For example, we have recently seen an increase in demand for skidmounted plant, pre-fabricated and tested in one of our Midlands factories and delivered to site ready for connection. This takes away a lot of the site complexity and the time required on site.'

Security of supply

While it's clear that the use of biomass heating is set to increase there are still those who have concerns over security of fuel supply. Mr
Walker suggests these fears are unfounded. 'When we first started manufacturing and supplying biomass boilers in the UK, back in 2004, there were certainly some fuel availability issues and some users were importing wood pellets from Scandinavia,' he recalls.

'That situation has changed dramatically, and there are now many more producers of wood chips and wood pellets. The biomass fuel suppliers that we work very closely with are currently exporting 90 per cent of their pellet production, so that capacity is there for use in the UK as demand increases.'

On the subject of fuel supply, there has been considerable speculation that the 'liberation' of shale gas will change the shape of energy production as, effectively, there are now many more years of gas supply available. Does Adrian Walker think this will influence the uptake of biomass and other renewable energy sources?

'No I don't, because the main issue is still carbon emissions and, irrespective of the source, natural gas is still a fossil fuel. Wood, on the other hand, is essentially carbonneutral as the carbon dioxide emitted from burning it is absorbed by the new trees that are planted to maintain the fuel supply.

Of course, there are some emissions associated with harvesting, processing and transporting wood fuels but these are minimal and are often
neutralised by increased tree planting by the producers. 'Having said that, I believe it's unrealistic to think that renewable heat sources will come to dominate heat production for buildings in the short term.

'We have a responsibility to use the planet's resources sustainably and responsibly and very often the best way to do that is to use a mix of different heat sources.

There are many projects where maximum efficiency is achieved through a combination of high efficiency gas-fired boilers as well as renewable heat sources.

Challenges to the industry

'In fact, this highlights another of the challenges facing our industry. Where a number of different heat sources are brought together it's vital that they are controlled effectively so that energy efficiency is optimised. To that end I would urge specifiers not to over-complicate their designs - keeping it simple makes it much easier to control.

'I would also extol the benefits of sourcing technologies from the same manufacturer, rather than mixing and matching from several. That way you can retain the control philosophy and supply chain support across the entire installation. Indeed, I would go further and suggest that there are major benefits to working in partnership with experienced manufacturers and tapping into their expertise and experience,' Mr Walker concluded.

Hoval in a nutshell

Hoval operates factories in Newark and Lincoln and manufactures biomass, gas and oil boilers as well as solar thermal systems, heat pumps, heat exchangers, thermal stores and pressure vessels. The company has also developed its own control systems to ensure that traditional and renewable heating technologies operate in harmony to deliver maximum efficiencies with minimum carbon emissions. In addition, Hoval is pioneering the use of ceramic filters for biomass boilers to help building operators comply with the most stringent air quality legislation.

Hoval was also one of the founders of the Centre of Renewable Energy in Nottinghamshire, where it runs a wide range of training courses on renewable energy for specifiers and installers.

The company's products are supported by extensive experience of integrating heating technologies, along with comprehensive maintenance packages and the ability to deliver complete turnkey solutions.

Established since 1897, Hoval holds a Royal Warrant and has supplied boilers and other heating products to many royal residences, including Buckingham Palace and Windsor Castle. Other installations include sites as diverse as Wembley, the Millennium and Emirates Stadia, Great Ormond Street Hospital, the Bank of England, the Tower of London and The Globe Theatre in Stratford.