Following a public health warning by the German government, the Global Warming Policy Forum (GWPF) has called on the UK government to halt the planned rollout of heat pumps, and to undertake an environmental impact assessment. The UK government is currently planning to rollout air source or ground source heat pumps to replace gas boilers for most of the country’s 26 million households, promising installation rates of 600 000 a year as soon as 2028.
In May, the German Federal Environment Agency (Umweltbundesamt, UBA) published a major study detailing the pollution threat to water supplies and public health from the refrigerants commonly used in air conditioners and heat pumps.
These refrigerants decay in the atmosphere to produce trifluoroacetic acid (TFA) and/or trifluoroacetate, which then passes into groundwater and drinking water, raising serious public health concerns.
Rainwater measurements commissioned by the UBA show that TFA concentrations have risen sharply since the 1990s. TFA is highly mobile, classified as hazardous to water and penetrates into groundwater and drinking water.
The German study notes that the emissions from air conditioning and heat pumps will "add a large additional share to the amounts of TFA or trifluoroacetate in the atmosphere.”
The refrigerants, initially hydrofluorocarbons (HFCs) and more recently unsaturated hydrofluorocarbons (u-HFCs and u-HCFCs), were adopted some decades ago because they are less harmful to the ozone layer and have a lower global warming potential than the chlorofluorocarbons and hydrochlorofluorocarbons that were phased out under the Montreal Protocol.
The problem is of particular concern because TFAs and trifluoroacetate are very difficult to remove from water, and break down only very slowly. The German government’s report observes:
“Due to the extremely high persistence and mobility of TFA and trifluoroacetate, the increasing use of halogenated substitutes with low global warming potentials leads to growing pollution of the groundwater and drinking water resources. Since persistent substances remain in the environment for a long time and neither effective natural mechanisms nor acceptable technical processes for removing TFA from drinking water resources are known, potential harm to the environment and humans can only be prevented by minimising the input of TFA and its precursors. Even if the deposition of TFA and its pre-cursors were to cease immediately, an extremely long-lived substance such as TFA or trifluoroacetate would remain in the environment for at least several decades.”
The report concludes that air conditioners and heat pumps are already adding significant amounts of trifluoroacetate acid (TFA) to the atmosphere, contaminating rain and water supplies, and potentially causing health problems such as liver and kidney damage.
It recommends that “natural refrigerants”, including ammonia, carbon dioxide and hydrocarbons (isobutane is already widely used in domestic fridges) should be investigated as an alternative working fluid for heat pumps..