Next Generation Wood Stove Design Challenge
Tracy Allen
Posts: 6,664
Finalists have been announced design challenge sponsored by Alliance for Green Heat. These are high-tech low-tech improvements in traditional wood space heating stoves. Some include electronics with O2 sensors, temperature measurement and automatic controls, while others focus on combustion and heat transfer issues. There has been interest in that sort of thing here, and the snowmageddon folks might have a special interest. The finalists will be tested at a public viewing in tents on the National Mall in Washington DC in November. Press release.
Comments
There's a link on that challenge page to a Tulikivi wood stove. This is a Finnish company who encases their stoves in soapstone hearths. They're very expensive but amazingly effective - the heat mass will easily warm a 1,500 sf home in snow country for a day after the fire has gone out.
With smaller homes and better stove technology it's possible to heat a home for the cost of your labor if wood could be available.
Thanks for sharing this one, Tracy.
Thanks for the info!
My last "shed" had a very small wood stove that I made for the building. The back up on that one was Kerosene, which actually wasn't and probably still isn't too expensive. Used to heat that one for a song.
Very curious to see where this all goes.
And you can always have more than one wood stove in a home.
On the other hand, the pollution issues around wood heat are very real and finding a way toward cleaner combustion would be a big plus. People throughout the Pacific Northwest still use quite a bit of wood for heat, but there are times that the smoke just settles in and won't disperse. Coal is even worse as we see what China is experiencing this winter.
Erlend,
treehugger
I can recall many a cold morning where I ran from bed to stove and dove back into bed awaiting the fire to take hold. Some days it wouldn't and one just had to decide whether to forget it and get to work, or to try again.
Kerosene stoves did at one point overtake wood. Throughout Asia they were very successful and Standard Oil made quite a bit of money exporting kerosene. In the US, the day finally came when the fuel oil truck just filled your storage tank once or twice in a winter. Or you hooked into natural gas.
To burn all night, a stove has to be tight with good dampers... and the quality of the fire wood has to be good as well. One needs something like oak and certainly not green.
I hate to say it, but part of the pleasure of wood heat is that you have to acquire the right knowledge and skill set. It is a Walden experience... recapturing the past by seeking primative and simple comforts. High tech just doesn't provide that.
Franklin stoves are notoriously poor performers in terms of good all night heat. They are difficult to build to be tight enough.
I did own a home once with a sawdust furnace and there were about 20 active lumber mills in town. That was thermostatically controlled and would go all night and into the next day. But if it went out, there was a trick to lighting it without having it backfire and burn your socks.
You NEVER ever do that! Not only do you waste a lot of heat energy just in drying off the wood as it burns, but you also get a lot of sticky deposits in the chimney. It's a fire hazard.
A clean burning stove reduces the particulates in the smoke to a quarter or less than a normal stove. But ONLY if it's allowed to burn it efficiently.
Efficiency wise, they say an open foreplace gets about 30% efficiency, but will draw so much air that it chills nearby rooms.
A normal stove will give 50% efficiency, without significant cooling, and a CBS will get you in the ballpark of 80%, also without the cooling effect.
If you want to significantly improve on a CBS you need to look on placement and mounting.
Common errors are 'multi-hole' chimneys(more than one stove/fireplace/whatever.)
A CBS likes to have exclusive use of the chimney. NOTHING must by mounted higher up, and anything further down should be at a significant distance.
The bore of the chimney and the attaching pipe must also fit the size of the stove.
Top-mounted pipes are better than rear-mounts on the stove. Bends should be curved, not sharp angles.
Never let the pipe be perfectly horisontal. It should rise at least .5" per foot towrds the chimney.
Make certain the join betweeen stove and pipe, and the one between pipe and chimney are airtight...
Automatic startups... Yeah, right... That's the first thing I would have disabled if it existed. I'm just a bit too scared of CO-poisoning to not watch the stove every F! moment until I switch it from startup to CBS running.
(I have a small Dovre 425cbs stove)
How do I know my stove is running efficiently?
It makes a droning/low thundering sound.
The colour of the smoke is also a good indicator. Light/white smoke is good. Grays means lots of particulates.
Another thing is the height of the chimney. Too high with no damper, can draw like a jet turbine, burn fast and hot but carry away all the heat.
Speaking of CO poisoning, some of these high tech stoves are gasifiers, under computer control. A person close the field told me that one design alternately gets the fire very hot and then hits it with a jet of steam from an attached boiler. That is the principle of water gas, heat+carbon+water breaks down into carbon monoxide and hydrogen. That used to be piped into peoples' homes. In the stove, that mix is burned right away or in an afterburner. A lethal mix--You don't want the control system to break down for lack of maintenance or care.
Here in the SF Bay basin, biomass burning is frowned upon, and on "save the air" days it is illegal.
Having thought about this project a bit, I fear that I am just plain against it.
For me, wood stoves are very much about the whole process that teaches one how to live in a self-sufficent manner. There are a lot of acquired skills and knowledge involved. And one has to develop the discipline to acquire wood for the winter, to store in properly, and to use it well. This is about taking responsiblity for oneself. In some ways, it is an analogy for living well. There is a time for everything and if one keeps patient and keeps working, things turn out well. If one wants to automate (or delegate) the process, there are more hazards and more risk of poor outcomes.
Added to all that, I have no idea of how to get the air pollution from wood heat under control. Electric heat with big power plants that scrub the pollution out seem to be more realistic.
Frankly, if ever I did anything else, it would be to buy a $3000 Napoleon pellet stove and feed it dried cherry pits from nearby orchards. Last year, 60,000 lbs of cherry pits were buried by these orchards. What a waste!
Moving the Smarts into the stove is really asking for trouble.
for one reason or another, expensive ovens using wood pellets can be installed as 'alternate heating' here in Norway.
(It's a requirement in the building code in most of the country. Can't have people freeze to death if a winter storm knocks out the electricity... )
The problem is of course that these systems use electricity for the automated feeder system.
As they say, "Wood heat warms you twice." I guess there is 'big money' in making pellets. If I had to buy pellets, I suspect I'd want coal or at least a mix of coal and wood. Others strongly dislike the smell of coal, but it is very steady heat.
Though I am fascinated by the digital advances, there are just some things that are wonderful to do by hand. I don't even own an automatic coffee maker. And I really believe that a lot of robots could benefit from a wind-up spring for motive power. People actually had routines and tended to quite a bit in the era before the 'couch potato'.
These days, I still walk the dog at least twice a day and consider him my personal trainer. Others pay a gym and run on a computerized tread mill while they Twitter away.
Are all stoves going to be testing with one specie of wood - Douglas Fir, Alder, Bay, Mesquite, Pine, Oak, Hickory, Hemlock, Madrone, Cypress, Cedar?
And is the ring density and knot density of the specie going to be consistent? More dense burns longer, knots burn longer and hotter.
Also, some species, such a Pine, have pockets of pitch created by disease and physical damage during its growth. Pitch certainly burns hotter and faster.
IN the USA, it would be easiest to burn Douglas Fir or Hemlock for testing as these are quite available as cheap graded lumber of great uniformity. Cedar and Pine are generally used for kindling as they are faster burning softwoods.
Oak is a wonderful slow burning hardwood, so is Hickory. Madrone is extremely long burning. But all of these are somewhat localized in availablity.
Nothing wrong with progress. But after relocating to Taiwan, I actually have only a tiny electric space heater for the winter cold. My years of all wood heating are long gone.
There was a time when the USA was heating about 75% by wood, then with the railways, the use of coal took over until we moved into the most recent use of delivered heat oil, natural gas, and electricity for the majority of home heating, with some local use of coal and wood.
Over half the trees cut these day are used for paper pulp. Firewood is no longer a big fraction of logging. And wood heat is mainly used in rural America, where fuel is cheap and easy to acquire. I suspect the availability of good cheap chainsaws is partly responsible for a revival in wood heat.
You certainly have some very wonderful wood stoves amongst the finalist.
I'm glad to tell you I use energy from below the ground outside, for heating the floors!
But I have to admit.. I use firewood in addition for the cold winter nights when outside temperatures are sub-zeros, speaking celsusdegrees. My J
Did anyone see this newsarticle?
http://www.huffingtonpost.co.uk/2013/02/16/norway-state-tv-nrk-shows_n_2701196.html?utm_hp_ref=uk
Here's the show...
http://tv.nrk.no/serie/nasjonal-vedkveld
Warning: very, very long videos...
People don't need to burn wood to waste it, with paperwork we consume more wood that termites. Paper logs made from rolled waste paper are pretty good heat, and a lot more enjoyable that using a shredder to secure sensitive documents.
Maybe we need a wood stove with a sheet feeder.
Some enjoy watching a fire, but warmth is really the best part. That's why the Japanese are so into hot baths, the Turks in to steam baths, and Scandinavians into saunas.
Of course, a couch potato will watch anything. But I'd rather turn on an electric heater and read a good book.
We are making offerings to Wood God. may he bless us with an endless supply of Baltic Birch and Aircraft Grade Plywood.
C.W.
I want Marine Plywood!
(Plans to build a small sailboat, but this stuff is expensive and frankly, not that easily available)
Incidentally, if you search on youtube you'll find lots of videos of people making briquettes out of old newspaper.
I tried it myself once, and found that using a shredder on the paper before soaking was the best way.
Rolled up or balled up paper was a mess and the briquettes tended to split open, resulting in uneven burn and all kinds of problems.
Presses to make the briquettes can be found on eBay...
Don't expect the same burn-time as briquettes made of sawdust, though.
Ok, I want to build an airplane, and you want a boat, so I'll include a request for more Marine grade plywood the next time I make an offering.
C.W.
Got any drawings, or do you just happen to have a couple of Rolls Royce Merlins and a need for speed?
The boat I want is this one: http://www.selway-fisher.com/PC1620.htm#TARM
Back to briquettes...
The manufacture of briquettes out of old newspapers can be mostly automated(if you can find a 5year old who likes to push newspapers through a shredder), and with a bit of planning, it shouldn't be too difficult to make a custom size that can be fed automatically to an oven.
Nice boat.
I'd like a Van's RV-8
http://www.vansaircraft.com/public/rv8.htm
It's an all metal one, but it would be good for my inner Walter Mitty...
C.W.
I think in third world countries the wood or biomass supply for specialized stoves is itself a cottage industry. On one hand, if the fuel needs to be collected or prepared by chopping or grinding or pressing for use in the stoves, someone will specialize in that and it becomes part of the local economy. Those who can't afford it resort to more primitive methods.
Biomass supply? Do you mean yak dung? Such people would buy a battery, a charger, and a TEG? I suspect a cheap disposible gas lighter is their primary fire starter.
Of course, if you mean a young sheep, which is also a TEG... that's a different story.
An automated brick-ette maker? Not in the 3rd world if there is a profit in making them by hand. Clean? Almost not an issue. People in Manila make there whole living picking trash that is toxic and bio-hazardous. Survival is not elegant.
AllianceForGreenHeat, thanks for jumping in here. You must have an antenna up for commentary!? I should mention that I have a personal contact with this project--One of the judges is a professor of environmental health here at UC Berkeley, and I have worked with him and his students for years on ways to monitor performance of biomass cook stoves and issues of use and exposure. These projects use the Stamp and Propeller processors that these forums are about.
Sorry, my comments were not meant in any way to be a personal attack. But engineers seem to often think that they can rescue the 3rd world with high technology while people in such places as outer Mongolia or the Tibetian plateau have adapted to living in a fashion that has worked for many centuries. Technology may actually just be a greater expense, and create an unneeded dependency. The yurt is an amazing piece of kit that provides comfort and mobility in a very harsh environment.
There as portions of the world that live without dependencies on the latest innovation and may even be in greater harmony with the environment. Wood heat is certainly a necessity if you have no nearby power lines and there is no service delivering fuel to you door, or if you become isolated by snow or roads breaking down.
And of course for many, it just has a charm and comfort of its own. A good wood stove becomes much beloved; a bad one is very tiresome and much hated. I've had both kinds.
http://www.nytimes.com/2013/02/20/world/europe/in-norway-tv-program-on-firewood-elicits-passions.html?_r=0