I have a solar heat source that will deliver between 80 and 120C temperatures. I want to power a steam engine with this heat but obviously, when the source is below 100C I won't get any power generated. I have considered instead of using water in the steam engine, ethanol. On the output side of the steam engine I plan to place a condenser, condense the ethanol and pump it back into the system. I believe the boiling point of ethanol is 81C. Other than the fact that ethanol is flammable, does anyone see any drawbacks to this approach?