500kW Biomass Wood Chip District Heating

National Botanical Gardens of Wales

National Botanic Garden of Wales (NBGW) is located near to the village of Llanarthney in Carmarthenshire, Wales. The gardens opened in May 2000 and are currently the most visited gardens in Wales. The gardens operate as a registered charity and are reliant on visitor fees, donations and annual funding from the Welsh Assembly Government. The site includes attractions such as the Great Glasshouse – the largest single span glasshouse in the world – as well as various offices, shops and café/tea rooms.


The rising costs of heating fuel and the costs of maintaining seven individual oil boilers led the client to consider a more sustainable and cheaper source of heating.


Sustainable Energy undertook an assessment of heating loads and profiles across the site and assessed the technical and financial feasibility for a biomass district heating scheme. Based on the findings of the feasiblity process, the client decided to progress the project and Sustainable Energy was appointed to provide project management services for the delivery of a biomass district heating scheme. The services provided include tendering support for boiler procurement, detailed system design with fossil fuel boiler integration and specificaiton of a control and monitoring system with SMS alarm service which sends the off-site maintenance provider a report of system alarms.


The biomass installation comprises a 500kW wood chip boiler and 30,000litre thermal store with the 1MW oil boilers retained in place and configured to supply standby and back-up heat. The fuel store consists of a rotary extractor at floor level, within a chip store that can hold up to 50tonnes of fuel. Heat is distributed across the site via an underground heat network which connects with the existing heating and hot water distribution systems in each building. Analysis of heat monitoring and plant operating data post-installation concludes that designing the system to ‘best practice’ with regards to the thermal store, distribution network and optimised control has resulted in a heating system with high seasonal efficiency, which has reduced the reliance of the site on fossil fuel.

This biomass installation demonstrates our continued commitment to the environment. We are grateful to the Carbon Trust for their support throughout this process. The professionalism, technical expertise and quality of advice and service we have received from Sustainable Energy Ltd. has been absolutely excellent

Dr Rosie Plummer Director of National Botanic Garden

READ MORE: Carbon Trust Case Study