The steam engine is an extremely efficient engine. The problem with a steam engine is the one major flaux. WHen the water runs out, there is not energy to run the turbine.
So what I propose is to add a condenser tank to the classic steam engine. Which could do two things.
1 it could allow for a greatly reduced loss of water. New water will of course have to be added occasionally, but not every few hours.
2 the condensation of the steam back into water will allow the cold water a more efficient way of heat up. As the heat from the steam dissipates the cold water can absorb all that heat.
These two modifications will allow the steam engine to again be a very efficient power output engine.
Additionally, adding the “Stirling engine-temperature difference engine” this engine can product its own external energy. http://en.wikipedia.org/wiki/Stirling_engine
Adding a tank to cendence the steam bakc into water, the recondencation wil also aid in the reheating of the water in the fisrt place