Renewable dimethyl ether (rDME) is developing into a renewable alternative to liquefied petroleum gas (LPG) and could change the global gas market in the long term. Because it behaves physically in a similar way to liquid butane and propane, it can be used as a blend component without costly changes to the infrastructure.
What is rDME?
Dimethyl ether (DME) is the simplest form of ether and is a colourless, non-toxic gas under standard conditions. It liquefies easily under low pressure. While conventional DME is mostly produced from fossil natural gas, rDME (renewable DME) is made from sustainable sources:
- Biomass and residues: manure, sewage sludge, agricultural waste and wood residues
- Power-to-X (E-DME): from captured CO₂ (carbon capture) and green hydrogen produced with renewable electricity
The carbon in rDME comes from biomass or from captured CO₂ and not from fossil deposits. rDME produced from residues and waste can significantly reduce CO₂ emissions compared with heating oil and diesel.
The alternative to LPG
The greatest advantage of rDME lies in its physical similarity to LPG. This makes it a so-called drop-in alternative:
- Infrastructure: rDME behaves like LPG under pressure. As a blend component of up to 12 % by mass, it can be stored in the same tanks, transported in the same road tankers and distributed via the same cylinders and lines. At higher proportions, seals, diaphragms and hoses must be DME-resistant.
- Blends: At the request of the World Liquid Gas Association (WLGA), the UN Sub-Committee of Experts on the Transport of Dangerous Goods decided in 2024 to permit LPG of UN numbers 1075 and 1965 to contain up to 12 % by mass of dimethyl ether. The rule has been incorporated into the dangerous goods regulations RID/ADR 2027.
- Clean combustion: rDME burns very cleanly, with almost no soot or fine particulates and with significantly lower nitrogen oxide emissions than fossil fuels.
rDME thus covers today’s core markets for LPG, such as the heating market in rural areas: businesses and buildings without a natural gas connection can gradually reduce the CO₂ emissions of their heating without switching to a heat pump or pellet heating.
What matters in vaporization
The gradual decarbonization of the heating market and of industry is leading to a rising proportion of rDME in LPG. For LPG suppliers, this means that existing transport and logistics routes remain usable. However, as the physical and chemical properties of rDME differ from those of pure propane/butane mixtures, vaporization systems must be specifically designed for it:
- Material compatibility: DME has strong solvent properties. Materials designed for pure LPG can wear prematurely or start to leak at higher rDME proportions. DME-resistant seals, diaphragms and hoses ensure tightness even with changing mixing ratios and, in future, in pure rDME operation.
- Physical properties: Lower energy density and a different enthalpy of vaporization change the flow and control characteristics of the gas mixture.
- Control: Valves and pressure regulators must compensate for changed density and viscosity values so that outlet pressure and combustion behaviour remain stable.
- Approvals: The units should be approved for today’s transitional operation and for future pure rDME applications.
Thanks to our many years of experience with vaporizers for various special gases, we have developed our vaporizers accordingly: Since 2025 we have been building rDME-compatible LPG vaporizers, currently on separate request. In future, all units designed for propane are to be suitable for rDME as well. The rated capacities of our units are achieved at saturation conditions with rDME just as with propane and butane.
We can also build complete rDME-compatible systems, as we manufacture systems even for ammonia, which is more corrosive still. We are currently working on lower-cost versions, because the materials for DME do not need to be quite as resistant as for ammonia.