Environment & Energy

All that really means is that for DME you have to inject more fuel by mass into the engine to get the same power as diesel. I don't see how that relates to "engine size."

For the same trip where you might burn 100 kg of diesel fuel you'd burn 154 kilograms of DME.

It's similar to the situation with E-85 flex fuel vehicles. They get much better mileage running on 100% gasoline compared to Ethanol but you are not changing the size of the engine. Increasing the size of the engine wouldn't improve the E85 mileage, it would probably decrease it.

DME is very similar to LPG (mostly propane) in it's handling characteristics. It's a "bottled gas."

By volume LPG and DME have a very similar energy densities. A gallon of DME will go roughly the same distance as a gallon of LPG but a gallon of DME weighs more than a gallon of LPG.

This extra fuel weight wouldn't matter so much for automobiles and trucks as it would for aircraft.

If our modern world civilization survives and we humans actually manage to quit fossil fuels I expect our aircraft will be running on carbon-neutral jet fuel synthesized in nuclear power plant complexes.