How to achieve efficient carbon neutral wood heating

[PVGeezer]

Carbon neutral is tough. Of course it used to be done. But fell, transport, buck, split, stack, transport, etc to support a modern home entirely with human and animal power is not realistic for most. (YouTuber SkillCult used to have a "one cord challenge" where the challenge was to process an entire cord with only an axe. I've never tried it but it's got to be a ton of work.)

Yeah for sure, not doing that. But with an electric saw and splitter, yes. I have an L2501 but I'm looking forward to one day replacing it with an electric tractor.

I heat mostly exclusively with non-electric stoves in the house (Hearthstone and Vermont Castings.) Have been doing this for 22ish years. My wood lot is almost a 1/2 mile from the house and my Kubota L2800 does the heavy lifting. I have refined my process where I skid entire trees up (minus smaller branches) and process in the meadow. This was driven from necessity - the woods is a swamp, we get so few freezes anymore, and between the day job and being a single dad made woods time scarce. I used to split all the dead Ash exclusively by hand, but the ash is gone and once I got into the Elm a hydraulic splitter was a necessity.

I mostly have oak, cherry and pine. Some are pretty darn big because I mostly cut older standing dead or windfall trees. I actually like burning the pine. It lights easy, burns hot and leaves very little ash to clean out. It's gotta be well seasoned but that's true of any firewood. Pine is light and all cellulose has a about the same heat content per pound so pine is undesirable if you're buying by the cord but if you're harvesting yourself it's not a big issue.

My house stove is a small insert, the only stove that would fit in the existing fireplace (no way my wife would let me remove that) so I can only burn 15 inch splits and no overnight burns. So I'm happy to have the new high efficiency heat pumps, now I can get some sleep and restart the fire in the morning.

I stay at least 2 years ahead, stack in a single north-south row in the meadow and let the sun and wind beat on it. I keep 5 cords of "this years fuel" in a wood shed so it's ready to go. Properly seasoned wood is absolutely key.

100% agree. 2 years seasoning minimum, 2nd year in the wood shed.

I run a Stihl 021 for limbing, and bought a Stihl MS362 for the heavy stuff. I recently bought an Asian clone of a Stihl 066 (kit form) for less than 2 bills and it is an absolute monster. It's heavy but I can't believe how fast it cuts. Starts on the second pull every time.

I just dont want a gas saw anymore, not only because of the CO2 but because small 2 stroke engines and I have never gotten along. I was looking at the Stihl MSA 300 battery electric saw, thinking I might get one of those for heavier cuts and keep the Ego electric for limbing and lighter work. Pricey though. I'm not familiar with the Stihl product line but testers say it compares favorably with the MS271. What are your thoughts?

On average I put 4 cords of well seasoned wood thru the Hearthstone in a season and really only have 1/8" or so of creosote. But my stove is really undersize for a 140 year old farmhouse so I mostly run it hard which cuts down on the creosote.

Yeah running my small stove full bore with dry wood I only get maybe a quart of creosote at most at my annual sweeping.

Most would say it's a lot of work and it is - but I don't want to sit around all winter and watch TV. Plus I'm only taking already dead wood or cleaning ups stuff on other peoples property that they want gone.

Im old enough now that I can see the day coming when I won't want to be putting up a lot of firewood anymore, but for now yeah is good healthy exercise and feeling a big tree keeps you on your toes for sure.

 

[PVGeezer]

Only reading on TractorByNets threads about them. I have split lots of Pine, Tamarack, Fir, Larch and Birch with the 25 ton hydraulic , even wore out the drive coupling over the last couple decades of use, but I think maybe by now they have hopped up the Kinetics to where maybe the hydraulics have less of an advantage on the tough stuff. Your plan sounds like it will cover all the bases.

Since I currently have a light duty (read: slow) electric hydraulic splitter my other thought was to get a more powerful 3 point splitter and run it off the tractor rear remotes. That would take me further away from carbon neutrality for now but when I eventually get an electric tractor I'd be golden. But having too many tools be tractor attachmentd can get to be a PITA because you're always taking them on and off.

 

[PrairieSwamp]

I just dont want a gas saw anymore, not only because of the CO2 but because small 2 stroke engines and I have never gotten along. I was looking at the Stihl MSA 300 battery electric saw, thinking I might get one of those for heavier cuts and keep the Ego electric for limbing and lighter work. Pricey though. I'm not familiar with the Stihl product line but testers say it compares favorably with the MS271. What are your thoughts?

I have to admit I haven't even looked at electric saws. I know some guys that love them but for camping and yard work uses not fuel processing. I also have to admit that I have paradigm issues - if something works I tend to stick with it. But I will make it a point to stop and look at that Stihl. My dealer is awesome and only a mile or so out of the way on the way home from work.

BTW I do have human powered saws of all types. I buy crosscut saws when I find them and they are reasonably priced as I have the ability to tune and use them. The people at the flea market or junk store are always like "Are you going to paint it up and hang it on the wall?" and I say "No I'm going to tune it up and use it!" I will do more bucking (never felling) by hand in retirement here in the next year or so. But I don't know that I can do 4 cords/year.

I actually like burning the pine.

A farmer neighbor wants some pines taken down. I am getting the logs for the sawmill but I have to take the tops as part of the deal. It's been a ton of work this winter but I have probably brought home 2 cords and have and 1 or 1-1/2 to go.

 

[PVGeezer]

I have to admit I haven't even looked at electric saws. I know some guys that love them but for camping and yard work uses not fuel processing.

I use my Ego saw for fuel processing now. I have four 7.5 AH batteries for it. By the time I tire those out (a couple of hours of bucking, more when limbing) I'm tired too so it's usually ok. If I have my Lighting there I can keep two charging and go longer but if I was younger I would probably become frustrated and want a gas saw.

I'm interested in the Stihl because a more powerful saw would be easier when I get into bigger trees. I had a big ole oak come down in Helene. Took me the best part of 2 days to cut that up using the Ego, but I got about 1.5-2 cords out of it.

But I will make it a point to stop and look at that Stihl. My dealer is awesome and only a mile or so out of the way on the way home from work.

Thanks!

But I don't know that I can do 4 cords/year.

I know I couldn't anymore.

A farmer neighbor wants some pines taken down. I am getting the logs for the sawmill but I have to take the tops as part of the deal. It's been a ton of work this winter but I have probably brought home 2 cords and have and 1 or 1-1/2 to go.

I have 2 or 3 acres of pines that were planted too close together by someone at some point in the past. I need to start clearing them out. They're around 8-10 inches. Any use for lumber or just good for firewood?

 

[OM617YOTA]

If you can pull your Lightning close, look at the pro level corded saws.

 

[PVGeezer]

If you can pull your Lightning close, look at the pro level corded saws.

Yeah good point. I was thinking about that. I still have an old corded saw but it's weak so I never use it. I can get the truck most places, but I would still need a battery saw for some work. Even with the truck right there the cord can be a PITA working around.

120Vac 20A corded limits you to about 2.4 kw vs the most powerful battery saws are a quite a bit more powerful, around 3-3.5 kw. Milwaukee even has a dual battery saw that they claim has a 5.8hp (4.3kw) peak output. OTOH the corded saw cost of ownership would be much less. Multiple batteries get expensive. .

So I guess I need to decide whether my next saw should be more powerful or less expensive. Ego has a new commercial saw product line now which would use my existing batteries, so thats a plus.

 

[OM617YOTA]

The battery saws are also more power......................while they last. Corded keeps going as long as you do. Obviously where the crossover point for efficiency getting work done will vary by person and job being done.

Home Depot used to sell their Dolmar/Makita rental gas saws at significant discount, maybe they do the same with their pro corded saws. Something like that is on my list to grab when I come across the right deal at a garage sale or swap meet. Or if I need one I'll just go grab one. Already have an 80v Kobalt cordless saw, and 034, 034S, and 500i gassers on hand, so "need" is very debatable.

 

[PVGeezer]

The battery saws are also more power......................while they last. Corded keeps going as long as you do. Obviously where the crossover point for efficiency getting work done will vary by person and job being done.

I have an older corded saw. Once I got the Ego I quit using it because the Ego is more powerful and faster. I'm old now and don't have the stamina I used to have to keep going all day. I find once I go through 3 or 4 batteries on the Ego I'm just as tired as the batteries are if not more so.

 

[Daddy Tanuki]

well I guess I am the outlier here. I use Husquvarna saws 372, 346, and T540 for fell, bucking and limbing. I use a Home built hydraulic splitter that currently has a 2 cylinder kubota diesel on it that I am as of last month running on waste motor oil that I clean with a centrifuge so fuel is free. the chainsaws of course are two stroke so it is what it is. I haul everything with a 7.3 diesel that I am slowly preparing to run on WMO as well. I used to burn about 3.5 cords a year, now after remodeling the house with new insulation and double pane windows I am down to about 1.5 cords and preparing to eventually make the swap over to a solar boiler backed up by a WMO burner for the boiler as well. so dump excess solar to the boiler daily and then int he coldest months use the WMO boiler to supplement.

I think if you have fairly straight grained wood then the kinetic style splitter that is electric powered might be the way to go. but i do not see you getting out of the using fuel to bring it from the location to the splitter. battery powered chainsaws with enough batteries will cut it, the eletric splitter will split it but I do not see any cost savings over the short or long term due to battery degradation. so you are just polluting in a different fashion... kind of a NIMBY sense.

 

[PVGeezer]

Well, to each his own. I personally hate the maintenance and reliability hassles and noise of small ICEs. Been running and maintaining them for well over 50 years and I'm done. If you already own them it's of course going to be cheaper up front to keep running them rather than investing in new electric equipment, but on a life cycle cost basis and including your time's value, maybe not so much.

I'm also done with the purchasing, transporting, storing, and transferring of fossil fuels. I think using WVO is great but it's an even bigger hassle than buying the fuel.

I much prefer working with batteries and electric motors. Just stick the battery in and the tool starts first time every time. But that's me. You are of course also free to do you.

I despise the oil companies (I've worked for more than one, big oil used to own most all the solar companies) and all the death and destruction that industry has created (including the WW2 Pacific Theater and more recent trillion dollar wars, massive oil spills, huge oilfield fires, the list goes on and on).

For now I'm stuck with one ICE, my diesel Kubota tractor. But thats going to change at some point soon. Compact tractors are a near perfect EV application. Tractors need gobs of low rpm torque and lots of ballast so electric motors and heavy batteries are good things. Most "hobby" farm landowners like me don't run their tractors for more than a few hours a day so charging time isn't a problem. When I can swap out tractors, all my 3 point and PTO implements will also switch to electric. So that's chipper, digger, bush hog, tiller, tater plow, scrape blade, and box blade. I could also get a 3pt hydraulic splitter, they're cheap, but that's a PITA if you're also using the tractor to transport the wood. I still need to get a backhoe attachment but I'm waiting because those need a subframe so are tractor specific.

Re environmental damage from oil vs. lithium, eveything humans do causes some kind of environment impact. That's inevitable due to the 2nd law of thermodynamics, entropy always increases. But for EVs powered by PV, theres really no comparison between the damage caused by 8kg of lithium and 20 tonnes of gasoline, fossil fuel shills' BS notwithstanding.




Besides, when the Zombie apocalypse comes I'll still be running my equipment (till my batteries die of old age) while the ICE equipment will be yard ornaments due to lack of fuel.

 

[Daddy Tanuki]

Well, to each his own. I personally hate the maintenance and reliability hassles and noise of small ICEs. Been running and maintaining them for well over 50 years and I'm done. If you already own them it's of course going to be cheaper up front to keep running them rather than investing in new electric equipment, but on a life cycle cost basis and including your time's value, maybe not so much.

I'm also done with the purchasing, transporting, storing, and transferring of fossil fuels. I think using WVO is great but it's an even bigger hassle than buying the fuel.

I much prefer working with batteries and electric motors. Just stick the battery in and the tool starts first time every time. But that's me. You are of course also free to do you.

I despise the oil companies (I've worked for more than one, big oil used to own most all the solar companies) and all the death and destruction that industry has created (including the WW2 Pacific Theater and more recent trillion dollar wars, massive oil spills, huge oilfield fires, the list goes on and on).

For now I'm stuck with one ICE, my diesel Kubota tractor. But thats going to change at some point soon. Compact tractors are a near perfect EV application. Tractors need gobs of low rpm torque and lots of ballast so electric motors and heavy batteries are good things. Most "hobby" farm landowners like me don't run their tractors for more than a few hours a day so charging time isn't a problem. When I can swap out tractors, all my 3 point and PTO implements will also switch to electric. So that's chipper, digger, bush hog, tiller, tater plow, scrape blade, and box blade. I could also get a 3pt hydraulic splitter, they're cheap, but that's a PITA if you're also using the tractor to transport the wood. I still need to get a backhoe attachment but I'm waiting because those need a subframe so are tractor specific.

Re environmental damage from oil vs. lithium, eveything humans do causes some kind of environment impact. That's inevitable due to the 2nd law of thermodynamics, entropy always increases. But for EVs powered by PV, theres really no comparison between the damage caused by 8kg of lithium and 20 tonnes of gasoline, fossil fuel shills' BS notwithstanding.

View attachment 281196


Besides, when the Zombie apocalypse comes I'll still be running my equipment (till my batteries die of old age) while the ICE equipment will be yard ornaments due to lack of fuel.

like I said I think the electrics will do it all but like you said, being that I already have fully functional gear i see no need to replaceat this point in time.
I think with the solar water boiler I will have hit the limit of what my panels can achieve and will not have any space to properly set up any more at least until I build the greenhouse...
The panels on the greenhouse i was planning on using strictly for heating and cooling of the green house so that I could grow vegetables year around though so was not planning on using them for anything else. only time will tell.

 

[Chispas]

I really like the idea of a battery chainsaw but until the price & weight come down im sticking with 2 stroke. Part of my living comes from arb work but for me, the numbers just dont add up yet.
Sthil MSA 220 35 cm bar is €700 list price plus another €800 for 2 mid range batteries & charger - no point having just one battery. Then thers charging on site - ask the clients if you can plug in ? or kit out your truck ? buy more batteries ? then thers the weight 4.5 KG for a 1.7 KW saw with battery, without bar, chain or or oil.
Compare this to the MS 201 t, 1.8 KW, 3.7 kg without bar, chain, oil or fuel but a list price of just under €900. 800 grams extra doesn't sound a lot but several hours in day add up. For homeowners the cheaper saws are an option but for pro use they just don't stand up.
Edit. Finishing off yesterday I’d taken the big saws up the hill so I cut down the stump with the 200, just kept it spinning & didn’t dog in. As Tinman would say , an angry little saw

 

[Daddy Tanuki]

I really like the idea of a battery chainsaw but until the price & weight come down im sticking with 2 stroke. Part of my living comes from arb work but for me, the numbers just dont add up yet.
Sthil MSA 220 35 cm bar is €700 list price plus another €800 for 2 mid range batteries & charger - no point having just one battery. Then thers charging on site - ask the clients if you can plug in ? or kit out your truck ? buy more batteries ? then thers the weight 4.5 KG for a 1.7 KW saw with battery, without bar, chain or or oil.
Compare this to the MS 201 t, 1.8 KW, 3.7 kg without bar, chain, oil or fuel but a list price of just under €900. 800 grams extra doesn't sound a lot but several hours in day add up. For homeowners the cheaper saws are an option but for pro use they just don't stand up.
Edit. Finishing off yesterday I’d taken the big saws up the hill so I cut down the stump with the 200, just kept it spinning & didn’t dog in. As Tinman would say , an angry little saw

real men do not carry creamsicles... they carry husquvarna XP series

 

[PVGeezer]

like I said I think the electrics will do it all but like you said, being that I already have fully functional gear i see no need to replaceat this point in time.
I think with the solar water boiler I will have hit the limit of what my panels can achieve and will not have any space to properly set up any more at least until I build the greenhouse...
The panels on the greenhouse i was planning on using strictly for heating and cooling of the green house so that I could grow vegetables year around though so was not planning on using them for anything else. only time will tell.

I did a solar thermal tube greenhouse last year. Uses a couple stock tanks for thermal mass and about a mile of half inch drip irrigation tubing on the north wall for the collector/radiator. It self heats on sunny days down to 5F or so but has a water stove backup for cloudy and really cold days. It still needs some electric to run the pool pump in winter and vent fan in summer.

I'll do a thread on it after I get through the winter and can post some seasonal heating numbers. I'm sure it's not cost effective compared to buying veggies at Walmart but it's nice having our own fresh greens all winter and a heated splash pool for the grandkids.

 

[PVGeezer]

I really like the idea of a battery chainsaw but until the price & weight come down im sticking with 2 stroke. Part of my living comes from arb work but for me, the numbers just dont add up yet.
Sthil MSA 220 35 cm bar is €700 list price plus another €800 for 2 mid range batteries & charger - no point having just one battery. Then thers charging on site - ask the clients if you can plug in ? or kit out your truck ? buy more batteries ? then thers the weight 4.5 KG for a 1.7 KW saw with battery, without bar, chain or or oil.
Compare this to the MS 201 t, 1.8 KW, 3.7 kg without bar, chain, oil or fuel but a list price of just under €900. 800 grams extra doesn't sound a lot but several hours in day add up. For homeowners the cheaper saws are an option but for pro use they just don't stand up.
Edit. Finishing off yesterday I’d taken the big saws up the hill so I cut down the stump with the 200, just kept it spinning & didn’t dog in. As Tinman would say , an angry little saw

Based on my limited experience with my Ego saw you'd want at least 3 batteries. The EV truck and two chargers takes care of charging them in my case. By the time the 3rd battery dies the first one is recharged.

I'm too old to want to climb trees at this point myself but I get the impression that many folks who do nowadays like a lighter duty electric saw for that work. Easy start and quiet so you can communicate with the ground crew.

For heavy work yeah, I've been looking at a couple and the big electric saws are massive.

 

[Chispas]

real men do not carry creamsicles... they carry husquvarna XP series

I’ve got 2 older XPs & they’re just plain nasty not for the faint hearted

 

[Daddy Tanuki]

I’ve got 2 older XPs & they’re just plain nasty not for the faint hearted

I have three of the 372 xp's two of them are tuned, put out as much grunt as a 395xp after tuning. but my they go through a lot of gas. use the 346 for smaller stuff or the T540.

 

[Coydon]

A good reference for discussion:

 

[Daddy Tanuki]

A good reference for discussion:
View attachment 283669

got a link to this? can't get it to expand to read it.

 

[Coydon]

Here it is with some collateral background: https://permies.com/w/heat#1991626

 

[Coydon]

I've spent the past two winters in a yurt I built from basic materials. Store bought lumber I cut on a table saw for the structure, and sewed the cover from a bolt of untreated canvas. The floor is shipping pallets screwed together with deck screws. The only synthetic materials used were polyester thread for the cover (as I was told linen or cotton thread would deteriorate from UV within a couple years or so) and a vinyl framed semi circle window used as a sky light in the roof ring next to the chimney jack (which lights up the entire place during the day).

Basic work was done with Ryobi 18V cordless tools charged off the solar panels. The exceptions were the table saw at one friend's, and the century old Sailcloth sewing machine that another had. The Ryobi chainsaw only has a 12" bar. My plantation pines are all around 10-12", no problems. I can take down and limb two of them on a single charge from a 9A battery. Only problem with the thing is it leaks bar oil wherever I set it, but I've switched to vegetable oil for the bar last fall and haven't noticed a problem yet- just need to keep it by the heater until ready to use.

Underneath the canvas cover I clad the yurt frame with cardboard sheets stapled to it, one layer on both sides. I burn a combination of seasoned hardwood bought from a friend's farm, seasoned pine I put up here myself a couple years ago, waste lath from a mill in town I pick up when I grab my mail, and various sticks gathered from the woodland floor around camp during the year. All in it looks like it is going to take about two cords to get me through the cold seasons this year.

I built a Rocket Mass Heater with a slight variation on the conventional design, using rebar through bricks for the walls of the mass, and infilling around the ducts with clay bricks I scored for free and dirt. The firebox is split firebricks clad in steel sheeting, surrounded by sand for insulation. The riser is ceramic wool (superwool, which has non toxic fibers when shipped) clad in stainless duct. The bell is a $30 oil barrel with the paint burnt/brushed off. Most of the ducting and exhaust stack were from the ReStore or the dump.

Only recently did I realize that since I am only running my 6kWh battery bank down to 90 or occasionally 80% each day and it almost always charges full before noon, I could be running an electric oil radiator thing to save some wood burning during the day. I sleep on the mass, and running the RMH in the evening makes sure the mass is heated until morning. On the -20* nights, the air is around freezing by morning, but the mass under the mattress is still warm to the touch and I'm usually comfortable without even the down comforter on top.

I did buy an $80 induction burner to cook with on warmer days, but most of the time just use the top of the barrel to cook and warm drinks while the room is heating up.

The whole carbon neutral thing seems a bit ambiguous, but with my side work to selectively harvest some of the plantation trees on the property and steward a transition to a mixed growth forest, I think of the lifestyle here as carbon negative, or more importantly, biophylic.

 

[PVGeezer]

There are some rows in that chart that don't pass the smell test. Take for example the comparison in carbon footprint between the modern woodstove and the rocket mass stove.

Modern woodstoves are around 80 percent efficient when properly operated. That means that the rocket mass stove could at best produce 25% less CO2 per unit of heat generated than the woodstove, assuming 100% efficiency, which of course is not the case.

Storing heat does not create more heat, so for the rocket stove to produce 1/5 as much CO2 as the woodstove to generate the same amount of heat it would need to be 5x as efficient.

The only way for the rocket mass stove stove to be 5x as efficient is for the wood stove to be 20% efficient rather than 80%. Someone would have to have wildly oversized the wood stove and be operating it horribly inefficiently far below it's rated capacity , or grossly overheating the house, creating lots of waste heat. No sensible person is going to do that.

Put another way, the chart claims that only 0.4 tons of CO2 are produced heating with a rocket mass stove annually. About 0.1 tons of CO2 are produced per MBtu generated burning firewood, so thats 4 MBtu, what you get from 0.2 cords of hardwood. My not so big house requires around 60 Mbtu over the heating season (about 3 cords worth of hardwood). So the chart is off by a factor of 15 in my case.

The chart is also in need of a row labelled something like "ability to integrate into an existing structure". In this category the rocket mass stove fails miserably. If I suggested to my wife that I was going to take up half the space in our small living room with a big ole chunk of brick or cobb I wouldn't be married for much longer.

I don't have anything against rocket mass stoves, they're fine for their application, but they have their downsides and are not 5x better than the alternatives. I don't like to see false advertising masquerading as a fair and balanced assessment of the pros and cons of the various options.

 

[Chispas]

There are some rows in that chart that don't pass the smell test. Take for example the comparison in carbon footprint between the modern woodstove and the rocket mass stove.

Modern woodstoves are around 80 percent efficient when properly operated. That means that the rocket mass stove could at best produce 25% less CO2 per unit of heat generated than the woodstove, assuming 100% efficiency, which of course is not the case.

Storing heat does not create more heat, so for the rocket stove to produce 1/5 as much CO2 as the woodstove to generate the same amount of heat it would need to be 5x as efficient.

The only way for the rocket mass stove stove to be 5x as efficient is for the wood stove to be 20% efficient rather than 80%. Someone would have to have wildly oversized the wood stove and be operating it horribly inefficiently far below it's rated capacity , or grossly overheating the house, creating lots of waste heat. No sensible person is going to do that.

Put another way, the chart claims that only 0.4 tons of CO2 are produced heating with a rocket mass stove annually. About 0.1 tons of CO2 are produced per MBtu generated burning firewood, so thats 4 MBtu, what you get from 0.2 cords of hardwood. My not so big house requires around 60 Mbtu over the heating season (about 3 cords worth of hardwood). So the chart is off by a factor of 15 in my case.

The chart is also in need of a row labelled something like "ability to integrate into an existing structure". In this category the rocket mass stove fails miserably. If I suggested to my wife that I was going to take up half the space in our small living room with a big ole chunk of brick or cobb I wouldn't be married for much longer.

I don't have anything against rocket mass stoves, they're fine for their application, but they have their downsides and are not 5x better than the alternatives. I don't like to see false advertising masquerading as a fair and balanced assessment of the pros and cons of the various options.

Paul Wheaton, the owner of permies is a divisive character to say the least. I have been involved in the rocket stove community for some time & have built a rocket bread oven. The claims made about efficiency by Wheaton have been challenged, in the past he claimed that a rocket stove only used 10% of the wood as a conventional stove. What I see from Wheaton is a lot of marketing bullshit in order to sell his videos. Most of the content is about older j tube designs that were surpassed more than a decade ago by the batch box design. Rocket mass heaters do need maintenance, especially if you use an oil drum as a bell, spalling will eventually eat it away. The cost of 1900 dollars to build ? no idea where that comes from, you could build out of found materials & just buy enough refractory bricks for the core.
Rocket stoves are not a panacea, they have their limitations & are best suited to smaller, open plan spaces. As for efficiency, there exists a spreadsheet where you can input the M3 of your building, the degree of insulation & the temperature difference between outside & inside you wish to achieve (the DeltaT) . Polution or contamination has been measured extensively by Peter van den Berg, Matt Walker & others using sophisticated & expensive gas analysers, as documented on the Donkey32 rocket stove forum
For a more measured, collaborative view of this subject, with a tonne of empirical evidence, try the batchrocket.eu site

Batchrocket.eu - Introduction

Introduction of the Batch Box Rocket, a stove with an extremely clean combustion. Designer: Peter van den Berg

batchrocket.eu

 

[PVGeezer]

Paul Wheaton, the owner of permies is a divisive character to say the least. I have been involved in the rocket stove community for some time & have built a rocket bread oven. The claims made about efficiency by Wheaton have been challenged, in the past he claimed that a rocket stove only used 10% of the wood as a conventional stove. What I see from Wheaton is a lot of marketing bullshit in order to sell his videos. Most of the content is about older j tube designs that were surpassed more than a decade ago by the batch box design. Rocket mass heaters do need maintenance, especially if you use an oil drum as a bell, spalling will eventually eat it away. The cost of 1900 dollars to build ? no idea where that comes from, you could build out of found materials & just buy enough refractory bricks for the core.
Rocket stoves are not a panacea, they have their limitations & are best suited to smaller, open plan spaces. As for efficiency, there exists a spreadsheet where you can input the M3 of your building, the degree of insulation & the temperature difference between outside & inside you wish to achieve (the DeltaT) . Polution or contamination has been measured extensively by Peter van den Berg, Matt Walker & others using sophisticated & expensive gas analysers, as documented on the Donkey32 rocket stove forum
For a more measured, collaborative view of this subject, with a tonne of empirical evidence, try the batchrocket.eu site

Batchrocket.eu - Introduction

Introduction of the Batch Box Rocket, a stove with an extremely clean combustion. Designer: Peter van den Berg

batchrocket.eu

Yep, I knew without looking for it that there would be some kind of financial incentive underlying the marketing BS. Since the stoves themselves are DIY it had to be selling videos or some such.

I'm glad to hear there are better information sources that take a more technically accurate perspective. For myself I can usually tell when something energy related is marketing BS within a couple minutes by a simple application of the laws of thermodynamics.

I like Ginsburg's formulation:

1. There is a game, which you are already playing. (consequence of zeroth law of thermodynamics)
2. You cannot win in the game. (consequence of first law of thermodynamics)
3. You cannot break even in the game. (consequence of second law of thermodynamics)
4. You cannot even quit the game. (consequence of third law of thermodynamics)

Like I said, I think rocket mass stoves are fine. They're not going to work for my traditional 1800 sq ft two story house with a bunch of small rooms in it.

That chart also underestimates the performance of modern air to air cold climate minisplits. My new minispits have worked great over the past winter. Design balance point of 0F has lived up to expectations, we had a couple nights down around 2F ambient and no problem maintaining interior temp. Seasonal average COP is running close to 3. I bought Midea units rather than the much more expensive Mitsubishis that are favored in the US and installed them myself, so my ROI should be around 7 or 8 years assuming they hold up.

Looks like I'm going to have around 10MWh of excess annual PV generation so I really won't be needing to burn wood at all except during grid outages as long as my net metering contract remains in force. I'm looking a little at seasonal energy storage options for when net metering eventually goes away. No compelling technology yet for that as far as I can telll.

 

[upnorthandpersonal]

That chart...

...also doesn't make a mention of wood boilers.