Dimethyl ether (DME) is considered as an alternative fuel for diesel engines. DME is used as aerosol propellant for example in deodorants, perfumes and air fresheners. DME is an excellent fuel for diesel combustion process, however, it is a gaseous fuel and requires a mild pressure to keep it in a liquid form. Fuel use of DME is not commercial today, but demonstrations are ongoing for example with Volvo trucks. In China, DME market for vehicles was 13 million tons in 2015. In Shanghai city, a field test of ten DME city buses has been running. In Japan, DME trucks have been running with business license plates and also other field studies with DME have been carried out. However, in general there is no large-scale supply and distribution system for DME as a transport fuel. (IEA-AMF Task 20, IEA-AMF Task 47, Volvo 2009, Hara et al. 2011).

Benefits of DME:
+ High cetane number
+ Efficient diesel combustion
+ Low PM emissions, low engine noise
+ Visible flame, odorous, no peroxide formation
+ Non-toxic, evaporates from water and degrades in air

Drawbacks of DME:
- Gaseous fuel, requires special engines and infrastructure
- Viscosity and lubricity are challenging (additives needed)
- Low energy content (large fuel tanks)
- Miscible with water
- Flammable, heavier than air