Saving petrol with PAG bio engine oil

A new fully-synthetic engine oil based on polyglycol, which is biodegradable, can provide a fuel saving of up to three percent in cars according to a research group at the BAM Federal Institute for Materials Research and Testing. BAM scientist Mathias Woydt has calculated that polyalkylene glycol (PAG) can reduce carbon dioxide (CO₂) emission by about five grams per kilometre. The benefits of PAGs in fuel economy are particularly pronounced in urban traffic says Woydt.

BAM has shown that PAG is biodegradable. "In addition, it is resistant to oxidation and has a low-friction character" states Mathias Woydt. Researcher Woydt, who has been researching polyalkylene for 15 years, tested the properties of the oils and has further developed them. "Because, before using them in internal combustion engines, one must understand how they behave, for example in a temperature range from - 40 °C to over 150 °C," says the friction expert. PAGs were indeed low-friction at the beginning of the work, but their oxidation resistance and environmental characteristics were insufficient. Today’s PAGs can fulfil all the criteria of bio-lubricants ("biolubes"). The range of the investigation included the viscosities of PAGs, their heat capacity or thermal conductivity at various temperatures and pressures as well as wear resistance.

PAG is not a new lubricant. It was used in World War II by the US Air Force in aircrafts and later temporarily in Formula 1. Currently, car manufacturers are under pressure as the binding target for the maximum CO₂ emissions from the EU-Commission is gradually falling. For 2015, the rate is 130 grams of CO₂ per kilometre. By 2020, new cars should emit on average only 95 grams of CO₂ per kilometre, according to EU’s plans. Should the engine makers produce engines that don’t achieve 95 grams per kilometer on average, then the manufacturers would be fined 95 euros for every gram of excess CO₂ emitted. The new engine oil would reduce these payments (carbon taxes). The monetary value of saving in CO₂ tax is ten times greater than the extra cost for the car manufacturer so says Woydt.

BAM has worked with various research projects on the development together with European car manufacturers. The chemical company Dow Chemicals provides the raw materials for PAGs and the introduction of the new engine oil is expected from 2016.

If the PAG engine oil is very successful, up to one billion litres of fuel per year can be saved in Germany alone according to Mathias Woydt. Also, the vehicle would have an oil change only about every 30 000 km. The new oils can also easily help meet the stringent European exhaust emission regulations because oils based on PAGs are metal and ash free. Thus particulate filters last longer, can be smaller and do not become clogged with engine oil ash. "This secondary effect must be taken into account," says the BAM scientist. "PAGs have better properties at low temperature than mineral oils."

Polyalkylene glycols are produced from gases such as ethylene oxide and propylene oxide, which in turn are obtained through the so-called cracking of longer hydrocarbon chains from naphtha or natural gas. But it is also possible to synthesise ethylene oxide and propylene oxide from renewable raw materials, like ethanol or glycerol.

Contact:
Dr.-Ing. Mathias Woydt
Department 6 Materials Protection and Surface Technologies
Email: mathias.woydt@bam.de

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