York opts for renewables

As part of its strategy for meeting challenging carbon emissions targets, York City Council is making use of biomass boilers and solar heating panels from Hoval. Recent projects include the Green Apple Award-winning Danesgate Skills Centre, Acomb Library and York High School. The latter project will use what is believed to be UK’s largest array of solar thermal panels.

“One of the reasons we’ve teamed up with Hoval is their willingness to provide a complete package from initial site inspection right through to ongoing maintenance,” explained the Council’s Sustainability Engineer George Sands.

“As well as supplying the boilers, fuel storage silos and fuel transfer system, they organise siting of boilers in plant rooms, connection and commissioning. This gives us one point of contact and total clarity of liability and risk.

“The products are also backed by a support package tailored to our needs, so we can be assured of a swift response in the event of problems. The fact that the boilers are manufactured in the UK also means there is lower embedded energy in each project,” he added.

The 973sq m Danesgate Skills Centre is a new building on an existing school site, where a 450kW Hoval STU wood pellet boiler is used to provide space heating and hot water. The existing gas-fired boiler has been retained as back-up. The sustainability features of this project were recognised in the International Green Apple Awards 2008.

At Acomb library the Council opted for 2 x 70kW BioLyt wood pellet boilers. The small footprint of the BioLyt has enabled the council to use biomass boilers within a small plant room space, while its automated functions (including self-cleaning heating surfaces and ash removal) help to minimise maintenance requirements.

The largest project to date is York High School where biomass boilers are combined with solar heating. For the general school buildings, 3 x 450kW STU wood pellet boilers have been installed for space heating and hot water – each served by an independent fuel silo to give the system high resilience. A further 2 x 450kW biomass boilers and 80kW of Hoval’s SolKit solar thermal heating systems have been installed to serve the swimming pool. This is believed to be the largest solar thermal array in the country and will meet the swimming pool’s entire heating load during the summer, with back up from the boilers at other times of the year.

“Using carbon-neutral biomass fuels is a very quick way to reduce carbon emissions, especially in older buildings where heating may account for as much as 40% of emissions,” George Sands noted. “However, before proceeding with any such project it is vital to establish which type of technology will deliver the best results.

“After a lot of research we concluded that wood pellets derived from wood processing waste offered the best results when biomass is the selected technology. Not only do pellets give more consistent and reliable combustion compared to wood chips, they also require less storage space, they lend themselves to automatic fuel feeding mechanisms and produce less ash. These are especially important considerations for sites such as primary schools, where caretaking services are generally part-time,” he continued.

The use of renewable energy sources has generated a lot of interest locally and wherever possible the new facilities are being used to educate people about sustainability. At York High School, for instance, the heating plant is linked to computer displays so pupils can see how much energy is being consumed. There are also plans to insert a webcam into the automated fuel feed system so that observers can see the pellets flowing through the system. This will also help with remote fault diagnosis on the BMS system over the web, as fuel feed blockages will be observed.

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