Heat pumps: why natural refrigerants are better for decarbonisation
All heat pumps use either natural or synthetic refrigerants. With many organisations actively considering heat pumps to reduce their carbon emissions, it’s worth exploring which is the better choice.
What are refrigerants?
Refrigerants are the working fluid at the heart of the heat generation cycle in heat pumps. Every heat pump uses one of two kinds: chemical or natural refrigerants.
What’s a chemical refrigerant?
A chemical refrigerant is one which doesn’t occur naturally. In the past, both Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) have been used as refrigerants. While they both performed efficiently in this role, they were found to be highly harmful to the environment.
CFCs were banned because of the damage they do to the ozone layer, while HFCs are being phased out under the Montreal Protocol because they have very high Global Warming Potential. (Some HFCs have an effect on climate change thousands of times greater than an equal amount of carbon dioxide.)
Although HFCs are still used in some heat pumps, the most common chemical refrigerants in current use are called HydroFluoroOlefins (HFOs). These are also likely to be phased out soon as they contain toxic chemicals known as Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS). These are chemicals that don’t break down naturally, and have been found in many watercourses.
What are natural refrigerants?
There are three main types of natural refrigerant: carbon dioxide, hydrocarbons (such as propane) and ammonia. Carbon dioxide and propane are most used in the refrigeration sector and are expected to dominate in heat pumps.
Are natural refrigerants cheaper than chemical refrigerants?
As their name suggests, natural refrigerants are naturally occurring, so they don’t have to be manufactured. That not only means they require less energy to produce, but they cost significantly less too.
For example, at the time of writing, one kilogram of carbon dioxide refrigerant might cost as little as £2.40, while the same amount of an HFC could cost more than £100. So, the cost savings when re-gassing alone could make a difference to your organisation’s bottom line.
Natural refrigerants are more efficient
Natural refrigerants such as carbon dioxide and propane are more efficient than their chemical counterparts at higher temperatures. They have a higher coefficient of performance (COP) than chemical refrigerants at usable temperatures from 60°C upwards.
Natural refrigerants perform well
They also produce high temperatures in a heat pump (carbon dioxide has been proven at temperatures over 100° Celsius). So, there’s no need to compromise on performance with natural refrigerants.
Sustainable heating for your organisation’s buildings
Natural refrigerants can play a huge role in heating your buildings sustainably. They can do so in a future-proof fashion, with better performance and lower costs than chemical refrigerants. What’s more, they can do it in a way that helps your organisation to achieve its Environmental, Sustainability and Governance (ESG) goals.
| Natural refrigerants | Chemical refrigerants |
|---|---|
| Economical – much cheaper than chemical equivalents | More expensive – total cost of ownership is more with cost to buy higher, cost to replace refrigerant losses over time higher, and cost to dispose at end of life higher. The refrigerants are more expensive and getting increasingly so. This makes maintenance and operations more expensive too, as well as disposal at the end of the asset life. |
| Effective – produce high temperatures at high COPS in heat pumps. | Environmentally harmful – HFCs have high global warming potential much greater than carbon dioxide. HFOs are linked to PFAS – toxic ‘forever’ chemicals |
| Future proof – can be expected to remain in use and plentiful supply | Likely to be phased out or banned – because of the threat they pose to the environment |
| Readily available – secure UK supply chain | Leaks need to reported as part of carbon emissions reporting – adding to an already complex administrative process for your organisation. |
| Can contribute additional value to ESG goals – helping to decarbonise heating without using toxic chemicals |
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