A friend of mine is moving to the country where he has access to unlimited quantities of hardwood fuel. He's looking to find a small boiler and steam engine, which he says would be about 10HP (8 Watts ?), with which he hopes to power a generator to provide all his electrical needs, with the boiler also serving to produce domestic hot water and heating.
Notwithstanding the size of unit quoted, is there anything off-the
-shelf known to anybody? I said I would ask the experts!
Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"
Having a boiler in light steam during the night time is not so much of a problem as long as the ash-pan area is correctly designed.
Err, pre-heated water stays hot in an insulated tank you know, perhaps people are forgetting that due to the onward scourge of domestic 'Combi' boiler?... As for electric power, lighting would be the main concern and all it would need is a set of storage batteries and an inverter.
Depends on were the boiler is located within the property and it's grounds, also, if you re read the OP you will see that this is not going to be in the UK, heck there might not even be insurance!
It is practical, just a lot of work and thought is needed to plan it all, it comes down to local conditions and what the alternatives are as to whether it's worth the effort though.
Oddly enough, today at the Statfold Barn open day, a group of us were puzzling over some very new looking equipment. In the end the consensus was that it might be the boiler for a workshop heating system. As far as could be made out, an automatic stoking system fed wood chippings from a large hopper to the boiler by means of an Archimedes screw.
The simple answer Chris is 'no' (AFAIK) there is not a pre-packaged unit available off-the-shelf that will do what you are asking.
However, can it be done is a different question to which the answer is 'yes' ...and... 'has been for quite some time, the technology for auto- stoking and grating is well known. We used to operate coal fired boilers with automatic stoking and grate agitation ....BUT ... the downside was that the smallest was about 150kW. They were also damned expensive bits of kit, with low day-on-day maintenance needs due to the Controls but eye-watering 12monthly grate replacements (the best agitated grate still tending to clog locally if not examined and attended to by eyeball-Mk1). A fluidic-bed boiler burning sawdust and chippings would alleviate that, but your mate would need very deep pockets. Just not viable for a small domestic situation. If it were mine I would opt for a regular wood-burner with heat recovery and possibly a Stirling with it's hot end in the flue running a car alternator for the batteries. Alternatively, ditch the wood idea and go for a small CHP unit which are available in small domestic sizes, with solar trickle for battery charging.
As for the Controls element, for any of the packages... there is nothing complex to them and the models/algorithms are all well known, the sensing for the grate is the trickiest to get right.
Sorry guys... a P.S. to the post of a few minutes ago....
Chris, if he doesn't mind tending the boiler himself, and it's only going to be fired for say during daylight hours, and he really must have 'steam', then there are quite a few plans available for regular wood-burning boilers of small size. Think in terms of the small Victorian/Edwardian Steam boats, there are boilermakers out there who will remake to the traditional designs. My library of old Light Steam power mags contains details which I'd be happy to scan/email if he is serious about going the steam route regardless.
FFS! The OP was talking about a private residence - at least he has not said that this would be powering anything more than a private residence - it's quite within the realms of reality and as for costs, this is relative to 'other solutions' such as having power lines brought to the property (assuming that it's even possible) or the logistics in trucking in fuel oil/petrol etc.
If you run a lot of superheat, a triple expansion engine, condenser, reheating and feedwater heating, you may get 15% net efficiency before things get old and start to degrade (based on my experience with power station performance tests, this is of the order of days, not years). You might get more by running a turbine into the condenser in addition to the reciprocating engine.
This means that you are thinking about 40-50kW of boiler capacity. That's going to need to burn 200kg of hardwood per day.
Of course, if the 8kW is peak load and the average load is significantly lower, then the costs and additional losses inherent in an inverter and batteries could make sense to allow a smaller plant, run at its design load rather than a large one turned down to the point of negligible efficiency.
It's achievable. I'm not sure that it's economic compared to wood for heating and wind/photovoltaic for electronics and lighting. Could have the heating plant capable of generating steam at sufficient pressure to run an engine for the workshop lineshaft. Manual stoking would be less of an issue for that use.
These thoughts are worth almost as much as they cost :-)