Unless your LEAF is running off PV, the NG conversion is actually a better environmental choice that our Colorado grid, and it has the same home fueling convenience
Could your converted car also take propane in a pinch ?
Where do you place the tank in the car ? I have read that modern gasoline car tanks are plastic but I presume that is not possible for NG ? I'm just guessing based on the price.
I think going solar could be cheaper. Or close in price. It would just be hard to make portable and practical.
As for propane there are several factors to think about.
If I did a 100% conversion to CNG I'd be able to use propane only if I lowered the compression ratio sufficiently, perhaps with a thicker head gasket, or some head machining. CNG would require a lower compression ratio too. The one problem is that CNG tolerates and benefits from a higher compression ratio than LP does. In a full conversion I'd also have to tap out the injector ports and install sparkplugs and also add on an ignition system, probably a wasted spark digital system like one made by CB Racing or MegaJolt. That would put me back another thousand or so and the system would not be able to use diesel. Propane would also require it's own tank for the propane.
If the conversion used idle diesel injection as the "spark" I would still have compression issues. Lowering the compression ratio of course would make it less efficient on diesel and also possibly harder to start. One idea I had was to use water injection instead of lowering the compression ratio which would also lower NOx and CO emissions even more, although that would have to be protected from freezing during the winter. Then again, with cold winter air it might not be needed. Also, if the engine is used only for a steady, low RPM, low load use, like as a pusher trailer with a preset load and used only in top gear, there is a chance that the air-fuel ratio of the CNG would be low enough that no engine knock or damage would occur, even without lowering the compression ratio or adding water injection. But with propane there would be more of a chance of harming the engine. However, with such an engine it would be very easy to go back to using diesel in a pinch, and only extremely small amounts of diesel would be needed for igniting the CNG when running off of it.
Another conversion is to fumigate the intake with either propane or natural gas in small amounts and use mainly diesel as the driving fuel. In small amounts there isn't any possibility of harmful engine knock, and the natural gas or propane in such small amounts will still help improve emissions. But other than that it would still be a mostly diesel engine, using perhaps one gasoline gallon equivalent of gaseous fuel for every three or four gallons of diesel.
LeftieBiker wrote:It seems to me that high grade biodiesel would accomplish your emissions goals with less modification - mainly a small second fuel tank and mixing valve.
Biodiesel would require more work on a regular basis. There aren't any stations in Gunnison that sell it. So I'd have to make do with used veggie oil from restaurants. Plus the stuff doesn't work well in the cold. I'd have to heat my whole fuel system. As it is, when it drops down below -30*F it is common for the regular diesel to gel, especially if I'm using the summer blend or from another town where it's warmer. I might have to put a heat exchanger on the exhaust to warm the engine coolant and fuel since this little diesel doesn't put out a lot of heat. I guess the thing is a bit too efficient. I can warm up the engine (and it has a good thermostat, trust me) and drive it around town and watch the temperature needle drop and it start blowing cold air out the of the heater, although on the highway the heater does pretty well until I start down a long grade.