I'm a big Renewable Energy fan (mainly windmills and solar). But I hadn't encountered the "rocket" systems before. Thanks enormously for bringing it to my attention.
I did a bit of web searching and found a bunch of good stuff on how they work and how to build them. Beautiful.
- Similar combustion efficiency to a pellet stove, but far better heat capture.
- Natural draft instead of forced draft by electric fans.
- Manual feed instead of electric auger, but batch, requiring no more (indeed, even less) attention than setting a fireplace fire.
- Thermal mass heat storage so a single fire heats for a day or more.
- No power or control requirements beyond setting and starting a fire every day or three if the house is getting too cool.
One thing that really impressed me is the hack of getting a high draft from a couple feet of "indoor stack", rather than an external chimney, by running a counter-current coaxial heat exchanger with extra heat added by the afterburner combustion on the inner, upward-flowing gasses and heat extraction from the outer, downwind, side of the flow. Cute! A pure-fluidic/convection heat-engine to pump the air and deliver the partially cooled result back down to the level of the fire for horizontal exhaust after nearly all the remaining heat is extracted from the fully-combusted exhaust. Extreme temperature differences produce a strong draft with only a couple feet of rise.
And of course:
- Cooking surface on the top of the heat exchanger/engine.
- Practically free but for labor. (Made of mud, firebrick, maybe some flue pipe, and a 55 galon "oil drum" or similar.
I'll be very interested in:
- Ash cleanout.
- Smoke from initial startup and how to avoid it.
- Longevity and failure modes of that "oil-drum" outer heat-exchanger wall.
My eventual retirement home is currently heated by solar and propane, with a gas forced-air furnace for main, a milliwatt-stat/pilot-light propane stove for backup (in case of power outage), and south-facing solar windows (which are fine for daytime but we have too low thermal mass for store for night or overcast days). I'd been thinking of moving my pellet stove there and getting a pellet mill to fuel off the annual weed crop and home-generated electricity. But this system looks like a GREAT "after a hypothetical fall of civilization" alternative. B-)
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"Obama’s Economists: ‘Stimulus’ Has Cost $278,000 per Job."
That means: For each job "created or saved" about five were destroyed.
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