Making a success of surface-water heat pumps
Surface water as a potential heat source for heat pumps abounds. Phil Jones would like to see it much more widely exploited.
Heat pumps are a long-established technology. They have been commercially available for decades, and their use is widespread in other countries — but they are a tiny share of the market in the UK, under 5%.
All heat pumps, particularly those that use surface water as their heat source (subsequently referred to as SWSHPs, for surface water source heat pumps), have had a problem in the UK — confidence. The problem of confidence comes down to a lack of information. Few installations means little data from working examples, which means little best practice. If investors don’t know what to expect from their new kit, they will be understandably reluctant to invest — so few new installations take place, and the cycle begins again.
CIBSE has been trying to address this issue, along with the Heat Pump Association (HPA) and the Ground Source Heat Pump Association (GSHPA) by producing its Code of Practice on SWSHPs. This code is designed to set the concrete standards and best practice that will give installers and clients confidence in the suitability and effectiveness of SWSHPs in their projects.
But what has prompted this renewed interest in the technology?
At present, the UK Government is facing a tough task in reducing its carbon emissions. It committed in June to reducing its emissions by 57% relative to 1990 levels by 2030, which means fulfilling all of its current policy pledges and more in order to bridge the gap. The progress the UK has made so far has largely been achieved in the power-generation side — with the vast majority of cuts coming from making the way we create energy cleaner by de-carbonising coal, oil and gas as well as promoting renewable generation from wind, wave and solar. But in order to reach the next level and achieve the 2030 targets, other sources of greenhouse gases are going to have to pull their weight.
Recognising this, the Government’s Committee on Climate Change recommended investment in key areas. They include carbon capture and storage, electric vehicles and sustainable heating — of which SWSHPs are a key pillar, along with heat networks. Another key breakthrough has been the Water Source Heat Map created by the former DECC and used in the Code of Practice. This definitively maps the potential for SWSHPs in UK waterways for the first time and provides a solid and reliable basis for assessing whether a spot is suitable.
It is difficult to overstate the importance of this for the industry, because it opens up an underused resource which has the potential to be as transformative as geothermal power in Iceland and solar power in Spain. The UK has surface water in abundance in its many rivers, lakes, streams and one of Europe’s longest coastlines. Ironically, even the canals which powered the industrial revolution and set Britain on the way to carbon-intensive industrialisation are an asset, running as they do in nice straight lines through our biggest urban centres where sustainable heat is most needed.
There are other practical advantages to consider. One is that water has a greater potential than the ground or the air to store heat, and water sources also tend to exist at a higher average natural temperature than the ground and the air. They also bring potential cost-savings by eliminating expenditure on alternative forms of heating and cooling that might otherwise have to be spent. For example, if used to replace a gas boiler the client need not invest in a flue and gas supply, because none is required.
Heat-pump systems can also be used to heat and cool simultaneously — removing the need for separate heating and cooling systems and making the overall process much more efficient. Rather than generating new energy or wasting surplus energy, the energy that has already been generated can be used again — which raises an important point about sustainability. It is about considering the lifetime cost of a building, not just the short term, and the savings in operation and maintenance that can be achieved with a properly commissioned SWSHP make a system worth the capital cost of installation.
This is where the Code of Practice comes in. As with any engineering problem, a project succeeds or fails based on the implementation of the solution. Any technology needs to be implemented with the best knowledge available to be truly sustainable in the long term. Even the best design can be a failure if it isn’t appropriate for the project. With this in mind, the code sets standards and best practice that a client can hold their installer to, in the knowledge that their work is informed by the most up-to-date knowledge in the industry.
This type of heat pump takes advantage of a natural resource that Britain has in abundance and will be a vital part of the UK’s heating plans going forward. With the benefit of saving British homes and businesses money in bills and maintenance along the way, this technology can help shelter them from fuel insecurity and attracting investment in the form of Government grants. If your building is close to water then think SWSHPs!
Phil Jones is an independent energy consultant and chairman of the CIBSE combined-heat and power and district-heating group.