Your description of the Kitson engine is very illuminating.  It brings to 
mind the project my boss is doing for EDL who make electricity from landfill 
gas using big gas engines. 
We are building a 50kW steam enine as an adjunct to the gas engine.  It will 
be run from steam raised from the exhaust heat of the gas engine, so 
improving the system efficiency.  It is actaully a separate engine, rather 
than an integration of the idea, but the principle is still there.
On another topic, centre wire DC systems are fine s long as the middle wire 
is firmly attached to earth and the centre voltage of the generator.  Our 
microgric has earth somewhere between the + and- wires so that shocks to 
ground are trivial - I actually find faults with a wet finger.  My house is 
centre tapped 24 volt and I blew up my CB radio when the 12 volt wire went 
open circuit!
Kali
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