HEAT PUMPS
We have the technology
Dave Pearson, group sustainable development director at Star Refrigeration discusses technology and the environment.
T
here is now a general consensus that climate change is happening and is it’s being dramatically exacerbated by the combustion of fossil fuels. Our
heating systems contribute significantly to poor air quality, which presents a clear and present danger to humankind and results in a huge financial burden to society. The dominance of fossil fuel combustion almost suggests that there are no alternative techniques proven to deliver heat, but the truth couldn’t be less true. In 2008, the UK Government put a support mechanism in place for employing alternative cleaner heating techniques, such as biomass, biogas and heat pumps. The Renewable Heat Incentive (RHI) is essentially finished, leaving the economic appraisal back in favour of gas. What might come next is far from clear, but it won’t be many heat pumps. On the surface of it, the RHI seemed like a good scheme, but the uptake was practically zero until 2018, when rather too much emphasis was placed on very large projects. For the domestic scheme, homeowners themselves had to bear the burden of full technical responsibility, full funding and full administration of the support mechanism. Given most domestic heat pump systems cost over £10,000 to deploy (£22,500 in my own case!) it is hardly surprising that uptake was low. In the non-domestic sector, the deployment of heat pumps from the introduction of the RHI through to 2018 was practically nil. I believe the main reason for this was lack of obligation and excessive risk. For industrial/ commercial schemes the RHI was based on metered outcome and payable at approx. 9.7p/kWh for the first 15% of maximum theoretical output of the system and then 2.9p/kWh. A tariff guarantee to secure operational incentive once commissioned was not available for large heat pump systems until it was eventually rectified in 2018. We then saw an over-demand on the RHI (principally new horticulture facilities) for heat pumps, just as the support mechanism ended. In my co-authored 2011 paper to the Institute of Refrigeration (Hoffman/Pearson) we described the success
16 June 2021
of new water source heat pump facility in Drammen, Norway. The heat pump was successfully extracting heat from the local salt water fjord and boosting it to temperatures viable for integration into a local district heating scheme (circa 90°C). The use of ammonia as the working fluid at such temperatures was the focus of the paper, noting the improved efficiency achievable versus recognised alternatives from the range of synthetic working fluids, in this case R134a. It was noted that ammonia would incur a 25% lower electricity bill for the operator, whilst simultaneously giving rise to a far lower global warming effect than any leaking working fluid. Prior to the Drammen facility it was generally thought that ammonia wasn’t viable above around 70°C. Combined with an ongoing perception that heat pumps were ‘unsuited to higher temperatures’ this motivated the author and Star Refrigeration to continue to speak out to address this false belief. This business drive and investment in the development of heat pump technology was eventually bolstered by significant legislative and policy support for the deployment of similar schemes in the UK. Around 2014, the Scottish Government observed the poor uptake of the Drammen-style projects being promoted by Star Refrigeration and opted, within the guidelines, to add further support. In 2018 West Dunbartonshire Council adapted their plans for the Queens Quay redevelopment project, with heat supply for the entire area based on river source heat pumps. The council appointed the delivery lead contractor role to Vital Energi and Star Refrigeration was appointed as heat pump supplier. Queens Quay is being redeveloped in Clydebank on the site of the former John Brown shipyard. A mix of municipal, commercial and residential properties are being built, all of which will have their sole heat source as district heating. The central energy centre has two 2.6MW river source heat pumps augmented with gas boilers, although these should not have to run until the system demand is much higher. There is also a thermal store (135,000 litres) which would allow 36 minutes at full load. Hugely significant to help
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