Automotive Engineering - December 2024 - 27

ENVIRONMENT FEATURE
INSIDE THE QUIET, LOOMING BATTLE OVER
AUTOMOTIVE
REFRIGERANTS
The VW ID.4 is available with a heat pump that uses R-744 refrigerant (also called CO2).
R-1234yf is used in almost every new car sold in the U.S., but the EU is discussing
a ban and the industry is investigating alternatives like CO2 and propane.
by Jim Motavalli
A
ccording to its manufacturer, Chemours, use of R-1234yf
has grown so much since the refrigerant replaced the longestablished
R-134a that it's now used in 95% of new cars
sold in the U.S. An estimated 220 million cars on global
roads are also using it. The problem with R-134a, which came in cars
and trucks in the 1990s, is that it's a gas with " a global warming potential
(GWP) that is 1,430 times that of CO2, " according to the EPA.
Since 2017, EU legislation has banned the use of any refrigerant in
new vehicles with a GWP higher than 150. That rule doomed R-134a
but opened the door for R-1234yf, which has a GWP of only four. The
EU is currently revisiting R-1234yf emissions rules and may ban the
substance in a few years. In the U.S., the EPA stands by its use.
Fighting over refrigerants is nothing new. In 2015, the European
Commission took Germany to the Court of Justice because it was allowing
automakers to use banned refrigerants. At the time, Daimler
argued that R-1234yf could cause fires in front-end collisions, but the
EU said, " these concerns were not shared by any other car manufacturer. "
Chemours describes R-1234yf as " a thoroughly tested, mildly
flammable refrigerant " and referenced an approval the European
Commission gave in 2014 after a scientific review. Mercedes-Benz is
now in favor of the newer refrigerant and said it has " implemented a
comprehensive safety concept to mitigate the potential risk of fire " on
cars fitted with R-1234yf, spokesperson Pascal Becker told SAE Media.
But does R-1234yf also pose serious health problems when it degrades
into the environment? Chemours defended its product vigorously
to SAE Media, claiming that it " delivers a 99% reduction in
global warming potential versus the incumbent refrigerant [R-134a],
advancing global climate targets without compromising performance. "
But concerns remain.
A 2021 study from the University of Bristol found that both R-134a
and R-1234yf result in emissions of organic trifluoroacetic acid (TFA),
AUTOMOTIVE ENGINEERING
but the latter is much worse in that regard. The study
found that changing from one chemical to the other
caused a " 33-fold increase of the global burden of
TFA, from an annual value of 65 tons formed from the
2015 emissions of 134a to a value of 2,200 tons formed
from an equivalent emission of 1234yf. "
Chemours said that TFA is " more than 95% naturally
occurring " and comes from " a variety of manmade sources,
including agriculture and pharmaceutical. " The company
also said, " numerous independent studies conducted
over the past two decades have concluded that TFA
from manmade sources does not pose a risk to the environment
or human health. " Chemours can point to a 2022
UN Environmental Programme report that found that
produced TFA is distributed globally and evenly distributed.
" This is unlikely to present a risk to humans or the
environment in these locations, but changes in concentration
in surface water (or soil) would respond rapidly to
releases. Monitoring of the environment for residues of
TFA would provide an early warning if trends in concentration
indicate rapid increases, " the organization wrote.
The UN report confirmed that TFA has a very long
life but did not sound a warning. " Because of its lack
of reactivity, TFA salts are persistent in the environment,
and estimates of half-life are uncertain but could
be in the range of centuries or millennia, " the report
said. " This persistence is not a major concern because
it does not react with biomolecules. TFA and its salts
are easily excreted by animals and do not bioaccumulate
in food chains. Salts of TFA have low toxicity to
animals and plants. "
December 2024 27
VOLKSWAGEN
Automotive Engineering - December 2024

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