ICE vs ECE dialogues
Another thing I have been looking at is combining a gasifier with an internal combustion engine for the power source. This seems immediately appealing now, and perhaps preferable to steam power, because even the oil in my dirty tank must be quite clean to avoid clogging the dirty filter, and because water would be at a premium in my bus when operating as a semiautonomous living space and I probably wouldn't want to use water that was or could easily be made potable on power generation.
If you have looked into both in detail, how do the operational aspects and costs of materials and complexity for gasifier / ICE stack up vs. pelletizer / steam engine?
I have looked at the system complexity issues, but have not seen practical experience, where the practical experience reveals true understanding.
Here is what I know, based on my own analysis and a report published by Dutcher Industries in California in the 80s. This was a project comparing ICE to steam. They concluded that the compete power plant costs of the ICE is comparable to the steam plant which included steam generator.
Gasifier is probably a maintenance nightmare due to gas purity requirements. I suspect that impurities will be hard to get out, which means that you can run your car, but for how long - is an open question.
Steam is mature and proven, with essentially lifetime design built into the system, more so than diesel. This is based on the fact that the temperatures in a steam engine are much less extreme than in internal combustion engines.
I think there's a reason why there are no gasifier cars running around, on pellet biomass. That seems it would be a great way to go - but I suspect the practical challenges of using a low-grade fuel with a high-grade engine is the stopping block.
This is not to say that such is impossible, but I don't know of any gasifier systems with proven longevity. Do you? It is also not to say that these cannot be made so, but I suspect that the gasifier technology would have to be very high, and I don't see an easy solution to maintenance necessitated by the scrubbing process.
I'm all for gasifier-steam engine - in which case it doesn't matter if the gas is not as clean.
Also, I noticed you generally seem to be going with hydrostatics for power and low-power electronics for control. Have you thought about high-power electric power systems as well, and what were your conclusions?
Indeed. The conclusions is that they are about 10x more expensive using existing technology. This can be ameliorated with open source, and it is probably for us to do in the future (about 3 years).
I find that direction attractive for overall simplicity's sake
If you have high tech power electronics and motors, yes.
as well as ease of advanced control and apparent efficiency. I noticed you have a posting for designing your electric power systems (and I hope to recruit a knowledgeable friend for this).
YES YES YES - power electronics are our next frontier after mechanics, and we intend to master it just as we're beginning to master mechanics. Power electronics are immediately relevant to welders, inverters, charge controllers, induction furnaces, and all of modern civilization as we know it. Cars are another application.
Separately, I have been looking at swing-piston, toroidal engine designs and barrel-piston and similar designs as bases for much simpler ICE / steam expansion engines with much higher mass and volumetric power densities than are usually seen with common designs. Do you have any background on these matters?
No, except for saying that non-linear motion is an order of maginitude more difficult to perfect then simple reciprocation.
I was speaking with a mechanical engineer a few months ago and if I can get a good design together I will send it off for a model-scale prototype to be made.
That's good, but at the same time, you're not addressing fuel issues, such as using biomass - the only form of robust, renewable chemical energy with excellent ecological and simplicity characteristics.
I would pursue this after you prove rigorously that pellet/steam does not meet your stated objectives. That is our present bias in our appoach.
Another comment - for water issues - you can do a closed-loop steam engine system. Its radiator would have to be 2x as large as a comparable car.