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The Bristol Castle Park water source heat pump is an award-winning, first-of-its-kind 3MW renewable energy facility. It captures heat from the city’s floating harbour to deliver low-carbon heating and hot water to more than 1,000 homes, businesses and schools across the City. As England’s largest harbour-based heat pump, it forms a vital part of the Bristol Heat Network and the city’s transition to cleaner energy.
Turning an ambitious idea into award-winning infrastructure, Sustainable Energy played the lead role in developing the Old Market heat network and the Castle Park Energy Centre. Appointed by Bristol City Council in 2018, the team acted as both strategic and technical lead, guiding the project from early techno-economic feasibility, concept design through to delivery and completion and helping establish one of the UK’s first large-scale water-source heat pump systems serving the city centre heat network. The first phase was completed in 2022, and was awarded a European Heat Pump Award.
Scope
In 2018, Sustainable Energy Ltd was first appointed by Bristol City Council and HNDU to establish a masterplan for the Old Market area of Bristol. Our appointment was followed by taking the project through feasibility, concept design stages, RHI and HNIP funding applications, heat network design, substation design, stage 3 technical design & specification for the energy centre, and procurement for the ammonia heat pump & harbour abstraction system. In 2021, the construction contract for the energy centre was given to Vital Energi, with Sustainable Energy Ltd retained to provide support in the roles of clients engineer and commissioning agent for the scheme with completion in March 2022.
Services
Masterplanning, detailed feasibility and techno-economic study, funding application to Heat Network Investment Program, detailed design for water source abstraction, heat pump specification and procurement, energy centre design, planning, surveys, heat network design, routing and sizing, substation design, developing technical requirements and specification for heat supply agreements with initial connections, Clients engineer during construction, commissioning management, data and dashboard development, RHI applications, EA compliance support, handover and O&M support, technical support for growth strategy.
Solution
The Old Market Castle Park Energy Centre is designed to extract up to 6 MW of low‑carbon thermal energy from Bristol’s Floating Harbour. At its core is a 3 MW water‑source heat pump system, which draws harbour water through a cantilevered intake platform equipped with submerged strainers. The water is then passed through rotating filtration screens to remove debris prior to entering the Star Energy ammonia-based heat pumps.
The heat pumps incorporate an automated tube‑cleaning system to minimise operational downtime and maintain long‑term efficiency. After heat extraction, the water is discharged back into the harbour slightly upstream of the abstraction point, ensuring adequate dispersion within the natural flow regime.
The system can deliver flow temperatures of up to 80 °C, with seasonal optimisation down to 70 °C during summer to maximise coefficient of performance. Heat generated by the water‑source heat pumps is stored in a 90,000‑litre thermal store and supported by 3 MW of backup boilers to ensure resilience and peak‑load coverage.
Heat is supplied to the district network at 65 °C, with customer return temperatures contracted at 40 °C. As the flagship installation within the Bristol Heat Network, the scheme demonstrates how a compact city‑centre site can deliver substantial decarbonisation benefits for both existing buildings and new developments.
The installation of the 3MW Water Source heat pump and abstraction equipment manufactured by Star Refrigeration were only capable of being deployed with the establishment of an expert multidisciplinary team with Vital Energi as Principal Contractor, Sustainable Energy Ltd as lead designers and DQS as QS/Project manager.