Three Letters Re: Some Thoughts on Burning Coal

Mr Rawles,
To chime in on the “heat to electricity issue”: A Stirling engine or “hot air engine”), might be what Dale from Vermont is looking for.  There are not many commercially available – one company was making them in New Zealand before the earthquake, but a quick Google search has also revealed that they moved their manufacturing to Spain. There may be others.  According to their web site they haven’t yet resumed their ‘off-grid’ line of  engine production.

They can be quite efficient, and run off any heat differential.  For example: Hot air temperature and a cold spring, or a wood stove and cold air outdoors.  They do need the heat differential, or in other words a heat sink, to provide convection and motive power.  They are several generations/styles that have been developed over the years.  I believe they could be made to turn an alternator.  There are many ‘do-it-yourself” videos on the net by people from all over the world. Hope that helps! – E.B.


In response to article Some Thoughts on Burning Coal, writer Dale from Vermont:
There are possibilities for building a 12 or 24-volt low voltage direct current system using automotive or aviation industry components and a wonderful little device known as a RhoBoiler, devised by the Rhodesians during the time of economic boycott by the world’s bully nations, which drove the Rhodies to greater self-sufficiency. The RhoBoiler varied in design and construction materials [often a former 44-gallon fuel drum] but was in general a low pressure remote boiler from which hot and sometimes pressurized water was supplied.
A recent web search turns up a few descriptions and pictures. An obvious starting place might be a scrapped-out water heater boiler, but obviously, pressure release valves are critical, lest a boiler explosion result. Most of the RhoBoilers were wood burners, given the local availability of wood as a fuel source, but the concept can certainly be adapted to coal-burning and electricity generation as well.


Regards, – George S.

Dale from Vermont wrote about the idea of a coal-fired home generator. Here’s a link to a $13,000 steam engine unit. The electrical output isn’t specified, but based on the 3 horsepower rating of the steam engine and
assuming about 40% heat-to-electricity efficiency, it might be as much as 1,000 watts – D.B. in Oregon