Alternative Fuels : OME

Synthesised alternative fuels are already a known known in Germany, judging by this research article into alternative fuel adoption preferences :-

“What fuels the adoption of alternative fuels ? Examining preferences of German car drivers for fuel innovations”, by Anika Linzenich, Katrin Arning, Dominik Bongartz, Alexander Mitsos and Martina Ziefle, in Applied Energy 249 (2019), p 222-236, DOI : https://dx.doi.org/10.1016/j.apenergy.2019.04.041

They write in their Abstact, “Some proposed synthetic fuels have favorable combustion properties compared to existing fuels, e.g., significant reductions in pollutant formation. However, penetration of such fuels requires a favorable social acceptance […] Among the five considered fuel attributes […] fuel costs had the highest decision impact for alternative fuel preferences, followed by fuel availability and usage requirements. Pollutant emissions had the lowest impact on alternative fuel choices. A market simulation of conventional diesel and alternative fuels (dimethyl ether (DME) and a blend of diesel with oxymethylene dimethyl ethers (OME)) revealed that currently a large majority of car drivers would prefer conventional fossil fuel options […]”

Clearly, some learning about alternative fuels needs to happen, particularly as there is an overarching plan, as the Linzenich et al. (2019) paper mentions, “The European Union aims at expanding the infrastructure for alternative (renewable) fuels in order to increase their market share to 10% and reduce the GHG emissions caused by transport by 60% till 2050. This implies the need for novel, alternative fuels with drastically lower GHG emissions than fossil fuels. Simultaneously, it is necessary to reduce pollutant emissions, in particular NOx and soot. Biofuels made from biomass, electricity-based fuels (e-fuels, produced from CO2, water, and renewable electricity), as well as the combination of these approaches (termed biohybrid fuels), have the potential to reduce GHG and pollutant emissions and can overcome the range issues of electric vehicles (EV) in long-distance transport. For example, the alternative fuels methanol and methane can each reduce NOx emissions by 30–50% and total hydrocarbon emissions by 15–30% compared to gasoline. Also, some alternative fuels for compression ignition engines can drastically reduce particulate matter (PM) emissions, e.g., in case of dimethyl ether (DME) by more than 95% compared to diesel fuel. Some of these alternative fuels can even be used in conventional vehicles, requiring no retrofit of the infrastructure, car, or engines.”

Beside dimethyl ether (DME) and its homologues, the (poly) oxymethylene dimethyl ethers (OME) series is also in the frame, and techniques for synthesising them are being developed, for example, “Conceptual design of a novel process for the production of
poly(oxymethylene) dimethyl ethers from formaldehyde and methanol”, by Niklas Schmitz, Eckhard Ströfer, Jakob Burger and Hans Hasse, in Industrial & Engineering Chemistry Research, 2017, 56, 40, p 11519-11530, DOI : https://dx.doi.org/10.1021/acs.iecr.7b02314

The researchers mention that OMEs have a variety of purposes, besides OMEs with between 3 to 5 carbon atoms in each molecule being touted as alternative fuels, “Poly(oxymethylene) dimethyl ethers (OME) are oligomers of the general chemical structure H3C-O-(CH2O)n-CH3 with n >= 2. OME are alternative fuels derived from the C1-value-added [methanol, methane foundation or base chemical] chain. OME reduce the soot and indirectly also the NOx formation during the combustion process in engines. Thus, OME have the potential to significantly reduce engine emissions, which recently undergo a heavy public debate. In addition, OME are also considered as physical solvents for the absorption of CO2 from natural gas, as safe fuels for direct oxidation fuel cells, and as green solvents for the chemical industry.”

Because OMEs can be made from syngas, with supporting chemicals, “Generally, for the synthesis of OME, a source of formaldehyde (e.g. aqueous/methanolic formaldehyde solution, paraformaldehyde, trioxane) and a source of CH3-end groups (e.g. methanol, dimethyl ether, methylal) are required”, and syngas can be made from anything that has carbon and hydrogen in it, this makes OMEs a good chemistry set for the energy transition. Today, OMEs might be made from Natural Gas, but in a few years time, OMEs can be made in a carbon-neutral ways from biomass and the carbon dioxide in biogas (amongst other renewable sources of carbon and hydrogen).

For progress in althenative fuels, going down the DME/OME route is suitable for a number of reasons. “Oxymethylene ether (OME1) as a synthetic low-emission fuel for DI diesel engines”, by Markus Münz, Alexander Feiling, Christian Beidl, Martin Härtl, Dominik Pélerin and Georg Wachtmeister, in, Liebl J., Beidl C. (eds), “Internationaler Motorenkongress 2016. Proceedings”. Springer Vieweg, Wiesbaden, https://dx.doi.org/10.1007/978-3-658-12918-7_41, reads, “Synthetic CO2-neutral fuels with oxygen content are referred to as oxygenates and show a promising way to achieve the set objectives. The combustion of oxygenates is soot-free, thus avoiding the NO x /particulate trade-off. The post-oxidation is improved by the presence of oxygen directly at the fuel. In addition, some oxygenates have no direct carbon-carbon bonds (so called C1-fuels), which prevents the formation of soot.”

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