The balloon bag vehicles are part of the story. I've always been into wood as a fuel because it's locally available and only 1/20 th. the cost to heat with in the wintertime as opposed to fuel oil. That led into studying the pyrolysis of wood to produce a fuel that's similar to natural gas.
It's amazing really ... during WW2 ... there were over a million vehicles in Europe running on coal or wood because gas & diesel were in such short supply.
If anyone has a little time ... this one is worth a watch. The producers did a pretty good job of explaining the history of it all. ( They explained the gas bags as well. )
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