If I wanted to set up a solar powered generator for a small combined heat/cooling and power plant, which is the better way to go?
With steam I like the idea that I can use the waste steam/heat for other uses (like absorptive cooling), and I’m pretty sure it would be easier to get a more usable power range from a steam engine. Plus I’d love the look of an old steam engine chugging away out back.
A hot air engine would obviously require less thermal input, but from what I’ve seen it’s quite a bit harder to get any appreciable power out of a hot air engine. Plus I may end up needing the steam anyways if I go absorptive cooling, but I could just put a hot air engine further downstream whereas a steam engine would probably have to be first in line after the boiler.
With steam your entire construction has to be able to stand up to pressure. This will make it very much more expensive not to mention heavier. I don’t know about where you live but around here any steam engine has to be certified pressure safe. Past history with steam engines has seen far too many accidents due to steam explosions. With hot air you only need to worry about high heat resistance and absence of combustible materials which is also required with steam systems.
Just because it sounds romantic does not make it practical or realistic.
I have to agree with elnav. I have some experience with steam systems and they require constant monitoring and maintenance to be safe. I am not familiar with hot air engines, but with anything steam, you would be making a serious commitment in terms of time, labor, and materials, regardless of your source of heat.