4 ms·
Methane still forces you to run on the Otto cycle or a variant thereof, not the more efficient Diesel cycle, so unless engine makers get HCCI right, renewables-
by hx87 10y ago
Methane still forces you to run on the Otto cycle or a variant thereof, not the more efficient Diesel cycle, so unless engine makers get HCCI right, renewables-to-diesel would still be a better choice.
- ryao 10y agoThe only thing that matters for adoption of renewables in transportation is $/mile. The efficiency of the heat engines is irrelevant. Natural gas is cheaper to make in a renewable manner than diesel (Europe is already mass producing natural gas from biomass) and has higher energy densities in J/g, which makes it suitable for transportation. The lower combustion temperatures do lower efficiency, but they also lower NOx emissions, which are a difficult problem for diesel. As far as aviation is concerned, natural gas could be more efficient not only due to the lower weight, but also due to the fuel being "precooled" in its liquid state: https://en.m.wikipedia.org/wiki/Precooled_jet_engine https://en.m.wikipedia.org/wiki/Precooled_jet_engine