Mercs go blue-green

Mercedes-Benz almost apologised for the delay in releasing its BlueTec technology — which uses ammonia to erode nitrogen-oxides from the exhaust — but blamed ongoing research, hiccups in Australia and demands from bigger markets in the US and Europe.

BlueTec is available on the E320 diesel that went on sale in the US late last year. Later this year in the US will be BlueTec versions of the M-Class SUV, R-Class people-mover and GL-Class 4WD.

Early in 2008, the BlueTec version of the new C-Class, the C220, will be launched in Europe.

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Some of the problem for a delayed Australian release of BlueTec can be aimed at government and also industry.

BlueTec technology requires diesel fuel to have a sulphur content of 5 parts per million or less — the standard in the US and Europe. Australia only recently reduced its sulphur rate to 50ppm which is too high to allow the BlueTec system to operate.

A second issue is the additional catalytic converters. Australian Design Rules require these converters to each have a heat shield — unlike other countries — but Mercedes quietly said that this impost was very expensive to design, engineer and produce.

The third issue is the size of the Australian market compared with diesel-hungry Europe and the potential of huge diesel sales in the US.

BlueTec technology, which is licensed to other manufacturers including the Volkswagen Group, was introduced in Mercedes trucks in 2005 and is basically additional cataytic converters.

A BlueTec engine has a primary converter — common in all new petrol and diesel-engined vehicles — to reduce emissions of carbon-monoxide and hydrocarbons.

A second converter makes ammonia that goes into the third converter to react with the exhaust and specifically target nitrogen oxides. The result is that 90 per cent of a diesel engine's nitrogen oxides are chemically changed into nitrogen and water vapour.

As nitrogen oxides are reduced, the soot particles visible from a diesel exhaust are similarly diminished.

Original BlueTec technology had a cannister of ammonia — it was coloured blue, hence the name — to be replaced every time the vehicle was serviced.

The C220 version has an onboard self-generating ammonia system.

Mercedes said the BlueTec C220 meets Euro-6 emission standards that apply in Europe from 2015. Australia this year adopted Euro-4 emission standards.

The C220 turbo-diesel produces 125kW and 400Nm and sips fuel at 5.5-litres/100km.