Bluetec makes diesel cars greener

Bluetec makes diesel cars greener By Vijo Varghese

The Nation

Published on June 26, 2008

Mercedes-Benz develops cleaner oil-burning vehicles as it seeks to bridge the gap between petrol cars and hybrids

Though Thailand's energy future is still unclear, signs are pointing toward biofuels or ethanol-blended fuels. While E10 and E20 fuel is already being sold, the government is now considering selling E85 fuel by the end of this year. E85 is a blend of 85-per-cent ethanol and 15-per-cent petrol. The move is almost comical considering there will be no vehicles ready to run on that kind of fuel by then.

The Thai government always has issues with future planning and auto companies as well as oil companies have urged it to get its bearings right and set down a long-term fuel-usage plan, so carmakers can roll out compatible products. But there are other carmakers which are unable to cope with E85 technology.

Premium brands such as Mercedes-Benz and BMW do not have E85 technology and developing the technology for a small country like Thailand is not feasible. These carmakers are instead turning to other alternatives like the Mercedes-Benz E-class NGT. This vehicle runs on compressed-natural gas (CNG) and is the best-selling version in the E-class range in Thailand.

The next option though is to turn to diesel. The fuel, that is likely to be the bridge between petrol and hybrids.

Diesel engines are not what they used to be. Gone are the smelly, dirty and high maintenance engines of a decade ago. New-age diesels provide better mileage and burn better although they do emit nitrogen oxides which cause acid rain and damage air quality.

"At Mercedes-Benz we have developed the next level of clean diesels which we call BlueTec. We achieve this higher efficiency in diesel engines in four different phases. Presently BlueTec diesel engines are being sold in the United States and Europe because this technology requires diesel with low sulphur content, which is not yet available in Thailand. The particles per million [ppm of sulphur] in the diesel in Thailand is between 350 and 280 while BlueTec diesel requires ppm to be below 50," said Klaus Fleweger, senior manager engine design, Mechanics and Components Group Research and Advanced Engineering Powertrain at Daimler.

The first phase of improving efficiency of diesel engines is to optimise the combustion process of the engine to minimise untreated emissions. The second phase is using oxidising catalytic converters to minimise emissions of carbon monoxide and unburnt hydrocarbons. The third phase is to have a particulate filter which reduces particulate emissions as much as 98 per cent.

The fourth and final phase is what makes BlueTec special. BlueTec diesel vehicles are fitted with AdBlue, which is an aqueous urea solution which is injected into the exhaust gas stream. The AdBlue helps reduce nitrogen oxide levels up to 80 per cent. The AdBlue is stored in a special tank and is refilled every 25,000km. BlueTec decreases fuel consumption by about 20 to 40 per cent, a great improvement considering that diesels are already much more efficient than petrol engines.

In Thailand, however, this is not possible unless oil companies raise the standard of fuel to Euro 4. Presently, only Euro 3 is being sold. Other manufacturers too cannot introduce clean diesel engines until higher-quality fuel is available.

"It is unlikely that there will be one answer for the fuel problem worldwide. Each country is likely to pick a solution that best suits its needs and raw materials. As for Daimler the next step will be to further improve the efficiency of the engines and make them run on alternative fuels. The second step will be to have a hybrid option in every model within the range and also a plug-in hybrid option. The third step will be to combine hybrids with diesel engines. [This is not being done currently as both the technologies are fairly expensive.] The final step will be to turn to emission free vehicles which run on either hydrogen or electricity," Fleweger said.

Currently, Daimler has about 100 hydrogen-fuel-cell vehicles being tested worldwide. Next year, Daimler will launch a petrol hybrid for the world market which was co-developed with GM and BMW. The S-class is the first vehicle which will carry this hybrid technology.