DME is the simplest of the ethers and the dehydration product of methanol.
What is it?
DME is the simplest of the ethers and the dehydration product of methanol. A gas at room temperature, it has physical properties very similar to LPG and can be easily compressed to a liquid. As for methanol, renewable DME can be synthesised from syngas derived from a renewable source or by the direct hydrogenation of CO2. Also like methanol, DME can be converted back into hydrogen when needed or utilised directly in a number of applications. DME can be synthesised directly from CO2 or produced via methanol. The direct synthesis of DME is more efficient than the synthesis of methanol.
Why is it important?
DME can be blended with LPG and used without changes to storage and transportation infrastructure or end use technologies when blended up to 10%. With minor modification to seals and elastomers, DME can completely replace LPG. DME is a better fuel for compression ignition engines than diesel, with a higher cetane rating and producing very low particulate and Sox emissions on combustion. Ironically, a major initiative in Japan to develop DME as a replacement for diesel in the 1990s was apparently halted due to the “success” of the diesel particle filter.
- Volumetric hydrogen density: ~95 kg/m3 (liquid at -25°C)
- Gravimetric hydrogen density: ~ 13% by mass
- Storage conditions: Liquid at ambient temperature and 4 bar pressure.
- Very low toxicity
- Does not pollute ground water or marine environments
- Excellent fuel for CI or SI engines
- Compatible with existing LPG storage and distribution infrastructure
- Better chemical/hydrocarbon fuel intermediate than methanol
- More efficient production than methanol
- Approximately half the energy density of diesel
- Diesel engines require modification for use (not a drop-in fuel for CI engines)
- Minor modifications required for use in LPG infrastructure if to be used at high concentrations
- Note: The TRL for DME is dependent on the feedstock employed for its synthesis. For natural gas, coal or biomass the TRL is very high (8-9), whereas from CO2 it is somewhat lower (5-6). The direct synthesis of DME from CO2 (not via methanol) is lower again (3-4)
- Develop direct synthesis from CO2
- Process development
- Catalyst development
- Reactor development
- Develop reforming process to produce H2 from DME
- Develop DME compression ignition engine
- Modify compression ignition engine for DME use
Known active organisations
- The Australian National University