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Month: September 2015

Diesel as a fuel is changing: Part 3 of 3

NExBTL a useful addition to biodiesel

Using biofuel admixtures in a higher dosage than the 7% currently known is now under discussion, and following a proposal by VDA, Daimler Trucks and Daimler Buses recommend the biofuel NExBTL as an admixture. This is based on hydrated vegetable oils or animal fats, and is already produced industrially. Whether as an admixture or in its pure form, NExBTL is able to supplement or partially replace diesel fuel without problems.

BTL as a fuel of the future for diesel engines


Second Generation Bio-Fuels

First-generation biofuels such as biodiesel made from rapeseed or sunflowers, or bio-ethanol made from sugar-beet or cereals as a substitute for diesel, only use part of the relevant plants to produce fuel. Accordingly they are sometimes in competition with food production. The same applies to NExBTL as a hydrated vege­table oil. All this will change with the advent of second-generation (BTL) bio-fuels, for which the entire plant is used for the production of fuel. This requires a smaller growing acreage and saves more CO2.

These synthetically based BTL fuels give rise to great hopes for the future. If correc­tly processed they achieve the same quality as diesel fuel, and have a higher energy density. BTL fuels can be used in unmodified diesel engines, which are easily the most widespread power units in trucks and buses. They are able to use the existing refuelling infrastructure, and can either be added to diesel fuel in any ratio without problems or used in pure form as a direct replacement. Not least, they also exhibit a very favourable CO2 balance and have the potential to meet future exhaust emission limits. In the view of experts, BTL fuels could cover up to 20 percent of the total European fuel requirement.

Daimler, Ulta Leitner, 2015

Diesel as a fuel is changing: Part 2 of 3

Biodiesel in pure form requires certain measures

biodieselAll in all, biodiesel reduces CO2 emissions by around 50 percent. It is free from sulphur and aromatics, and biologically degradable. In high concentrations the reverse side of the coin is incompatibility with some plastics and rubber, poor low-temperature performance, an inadequate shelf life and higher nitrogen oxide emissions during combustion. Some fleets have even gone beyond biodiesel as an admixture, and are refuelling their vehicles with pure biodiesel to save costs, how­ever owing to the limitations of biodiesel this is not possible unreservedly.

All Mercedes-Benz commercial vehicles have been approved for biodiesel since 1988, though initially with the proviso of shorter oil-change intervals. New Mer­cedes-Benz trucks and buses are optionally available with extra equipment for bio­diesel, and retrofitting is possible for vehicles already in operation. With a pack­age consisting of modified unit pumps for the fuel injection system, a fuel pre-filter with a heated water separator and an auxiliary tank for conventional diesel fuel to ope­rate the auxiliary heater, oil-change intervals are now approaching those for en­gines with conventio­nal diesel fuel. And not least, the operating life of the auxiliary heater is maintained thanks to operation with conventional diesel fuel.

Using biodiesel is not possible in vehicles with an EEV emissions classification, as biodiesel generates up to 20% more nitrogen oxide emissions than diesel fuel based on mineral oil.

The use of non-estered, practically unprocessed vegetable oils in commercial ve­hicles is definitely not recommended. This raw material for biodiesel is subject to inadequate checks and causes damage to valves, injection nozzles, pistons and piston rings. There is also a risk of oil dilution and partial breakdown of the engine oil, with potentially serious consequential damage.

Daimler, Ulta Leitner, 2015

Diesel as a fuel is changing: Part 1 of 3

Diesel-alternative For the foreseeable future diesel will remain the number one energy source for heavy commercial vehicles. Worldwide availability, a well-established infrastructure and highly developed engine technology with respect to performance and environ­mental protection make diesel the clear front-runner among fuels. Nonetheless, the diesel of the future will be different from the current product for reasons associated with environmental protection, energy costs and the security of energy supplies.

With respect to conventional fuel, Daimler Trucks as a manufacturer is strongly in favour of sulphur-free diesel fuel with the lowest possible aromatics content, such as is used in the industrialised countries. Biodiesel is increasingly being added to diesel fuel even now, and the EU has announced a target content of 5.75% by the year 2010.
Biodiesel is not only gaining in importance as an alternative fuel within the EU, but also in other regions of the world such as NAFTA. The relevant requirements and standards vary greatly from region to region, however. There are very significant differences between North America, Brazil and the EU, for example, and a stan­dar­disation process would be very desirable. The same applies to all other biofuels and alternatives.

Daimler, Ulta Leitner, 2015