Just when you thought the ‘demonisation’ of diesel was well and truly dead and buried, as most people now understand that Euro-6 diesels are extremely clean, a press release from the Natural Gas Vehicle Alliance lands in my email inbox.
Headlined “Government’s Clean Air Strategy ‘airs’ on the side of caution – It is time for the UK to switch from dirty diesel HGVs to natural gas” (their caps not mine, by the way) it states: “It is time for the UK to switch from dirty diesel HGVs to natural gas. If vehicles were to use natural gas, NOx emissions could be reduced by 74%, Particulate Matter by 96% and if they use Biomethane, carbon emissions would also be reduced by over 80%” (again, their caps).
Naturally these precise numbers for emissions reduction piqued my interest, as there is some debate about the difference in emissions between Euro-6 diesel and the current generation of gas trucks. Tests carried out last year found that gas trucks are indeed cleaner than Euro-5 diesel but with the latest Euro-6 emissions standards there is in fact little to choose between gas and diesel on NOx and particulates.
A request for an interview with NGVA CEO Mike Foster to explain his numbers was declined but his head of external affairs did send us a statement admitting there is “little difference” between Euro-6 diesel and gas engine tailpipe emissions. No explanation of where their original claim for a 74% cut in NOx and 96% cut in particulates came from, which makes their original “dirty diesel” release even more disgraceful.
The issue of well-to-wheel carbon emissions for conventional gas and diesel fuels is quite complex, but comparing carbon emission from biomethane with those from standard diesel is equally wrong-headed and misleading. Switching from fossil-based diesel to biodiesel would produce a similar cut in carbon output.
Operators need good advice on how to reduce emissions to comply with the government’s ‘Road to zero’ strategy, not mis-leading mud-slinging by proponents of one fuel technology.
