Alcohol fuels for PHEVs

Gasoline, over time, will go bad. Its component parts will oxidize, break down, or even evaporate away. This leads to lower octane, and the formation of gums and varnishes that clog the fuel system and possibly damage engine components. I don't know how much that is true of diesel, but I do know that bacterial growth in it can lead to clogging the fuel filters and lines.

The sealed and pressurized fuel system of a car prevents and delays some of those issues. Yet a PHEV that stays in EV mode for too long will eventually result in wasteful maintenance cycle to burn off some of the old fuel. As PHEVs gain longer EV range, the more often these cycles occur.

So I started wondering if alcohols go bad in the same way as gasoline and diesel. I know liquors go bad, but that is mostly the compounds that give it flavor have 'turned'. So do methanol, ethanol, and butanol breakdown into components that will harm the engine in time?

 

I think the issue is potential phase separation; too much water and the water and alcohol mix separates from the gasoline. Get to E30 or higher, and it is no longer an issue.

The 6 month bit might be for gasoline in general. Lawn mower manuals were saying not to use last seasons fuel before the ethanol mandate.

The freeze or melt point of butanol depends upon the isomer. n-Butanol, the most common, is in the negative 120's Celsius, while t-butanol can be solid at room temperature. It can be said that the trace chemicals of gasoline and diesel are the issue. Neither is a pure compound, but a mix of various hydrocarbons. Being pure is likely why an alcohol would work out, an is actually easier to design engines for. They have been around, either straight or as flex-fuel, for awhile. Methanol is common for racing, and Brazil has E20 to E100 flex fuel cars. I think Honda once announced the development of a E0 to E100 flex fuel.

Cost is the issue, but I'm looking long term at PHEVs that are long EV range, when Phevs and hybrids are more common in general. The lower demand and need for the fuel would hopefully make paying more for something renewable socially acceptable. Alcohols could face some of the same infrastructure issues as hydrogen though.

An issue might not be the fuel, but with the other side of the maintenance cycle. Circulating the oils and fluids can be done by the electric motor. Still an inefficiency, but electricity can be made with less baggage than the liquid fuels. But perhaps the engine needs to warm up for something. Perhaps to boil off trace water in the oil, but where does that water come from? Some might work its way into the crankcase as condensation, but wouldn't most of it come in with the air charge and the combustion process. Then the water is bad because it can form acids with the scorched particles that form in the oil, which should be reduced with the use of ULSG, and alcohol fuel is sulfur free to begin with.

Why would that be the controversial view? There are downsides to using high pressure gases. One of which is that the heavy, bulky tanks limit car design. I haven't heard of anyone suggesting using coal dust in diesels, and emissions isn't a sole reason for that. The liquid fuel doesn't have to be of the future as it is put. Renewable diesel and gasoline are already possible. As with alcohols, it is the issue of costs.