Carbon-neutral wood replaces coal to heat school in Wales
Over 30% more efficient than the coal-fired boilers they have replaced, these Hoval boilers in a Welsh school burn wood pellets — so they are carbon neutral.
As part of its commitment to reduce carbon emissions, Caerphilly Council has replaced four coal-fire boilers at a school with three wood-burning boilers from Hoval. These boilers each have an output of 350 kW and were installed at Pontllanfraith secondary school by Lorne Stewart. New stokers and feeders were also installed, enabling wood pellets to be fed to the boilers automatically to achieve precise control of heat output. The boilers are linked to a control system to bring them on in sequence as required. The wood pellets are derived from sustainable sources, and the carbon dioxide produced during combustion is equivalent to that consumed by the trees during growth. The pellets are stored in the existing coal bunker, which has been refurbished and waterproofed. Stoking is automatic, so no human intervention is needed. John Davies of the council’s property services department, says, ‘Although wood has a slightly lower calorific value than coal, the new Hoval boilers are 90% efficient compared to the 68% efficiency of the coal-fire boilers, so we are achieving significant improvements in efficiency. The boilers have now been operational for about six months, and we are very happy with their performance.’