Protecting the Climate with Synthetic Fuels


RWTH researchers assess the environmental impact of new fuels made from oxymethylene ethers


The transportation sector is responsible for about one fourth of greenhouse emissions worldwide and contributes to local pollution, in form of nitrogen oxides and particulate (soot), especially in urban regions. In order to mitigate such adverse environmental impacts, RWTH scientists are developing alternative fuels from sustainable sources.

As part of the Copernicus Project “Power-to-X,” an interdisciplinary working group is carrying out an ecological assessment of oxymethylene-based fuel, OMEx for short. Involved in this project are the RWTH departments of Technical Thermodynamics, Process Systems Engineering, and Combustion Engines as well as the Institute of Technical and Macromolecular Chemistry.

The collaborative project is coordinated by the Power-to-Fuel project house established through the RWTH Strategy Fund and the Cluster of Excellence “Tailor-Made Fuels from Biomass.” The results of a study by the group have now been published in the journal “Energy & Environmental Science.”

Tailor-Made Fuels

In the combustion process of traditional fuels, carbon dioxide is generated. Alternative fuels are capable of closing the carbon loop as they can be manufactured from carbon dioxide. To this purpose, carbon dioxide is turned, in combination with hydrogen, into tailor-made fuels. As long as the hydrogen utilized in this process is manufactured using renewable energy, such fuels are nearly climate neutral.

Oxymethylene ether-based fuel, OMEx for short, is such such tailor-made fuel. Due to its molecular structure and high oxygen content, compared to fossil diesel fuel, the combustion process of OMEx is characterized by significantly reduced soot emissions and thus results in lower nitrogen oxide emission. Thus OMEx-based fuels not only provide the opportunity to be climate-friendlier, but also reduce other environmental impacts such as the nitrogen oxide and soot emissions of traditional fuels.

For the new study, an analysis of an OME1-diesel blend was undertaken, which took all aspects from the generation of energy from wind through to combustion on the road (wind-to-wheel) into account. A new route for a more efficient production of OME1 was developed. The study shows that compared to the traditional route, this pathway results in a 12 percent increase in efficiency and thus in a decrease in hydrogen demand.

The eco-balance demonstrates the potential of OME1 as an almost carbon-neutral fuel: by exchanging 24 percent of fossil-based diesel with OME1, emission gas emissions can be reduced by up to 22 percent. At the same time, measurements show that the new fuel can reduce the emission of nitrogen and soot by 43 percent and 75 percent, respectively.

With sufficient renewable electricity available, OME1 blends may serve as a promising first step towards a more sustainable transportation sector.

Link to the journal article: Cleaner Production of Cleaner Fuels

Source: Press and Communcation