2018 New Generation Wood Stove Design Challenge - Pics & Thoughts

[spirilis]

I visited the 2018 Next Generation Stove Design Challenge organized by Alliance for Green Heat (http://forgreenheat.org) on Sunday afternoon at the National Mall, Washington DC. It was as perfect of weather as any (dry, ~40-50F) and the tent was cozy and slightly smoke-smelling as one might expect for a wood stove demo...

(broken link removed to http://forgreenheat.org/2018-stovedesign/stovedesign.html)

First up where I entered, I saw SBI's automated stove, the Green Box Stove.
This stove does not generate electricity, just uses a small amount of it to automate the temperature by regulating against the flue temp to keep it within an efficient zone (~400-900F). What struck me most about this stove is the huge glass, even bigger view than my ESW Madison, although not all of it was usable firebox... seems like the secondary tubes and other stuff up top were visible.

- note that big banner was for the VcV stove next to it, not the SBI Green Box

The VcV was next, although I don't recall talking to them about it. Seems I missed that one and moved on (some of the vendors were quite busy with others asking 50 questions like I do )

In any case, I'll provide a pic and the literature I grabbed from them:





Next is the 509-1 Optimum, a "pellet" stove specifically designed with a 5 inch wide feed tube to burn North Idaho Energy Logs and similar stuff.
The inventor said this unit is ready to go right now and you can buy it, but he will be working on some sort of design for rectangular bricks.

IIRC rectangular bricks can work with it, just hit or miss, but anything larger than 5 inches is a no-no with this unit. With anything besides round briquettes the problem is which axis they expand. He described coming up with a design where you have a rectangular feed tube with a center divider and 2 stacks of bricks that alternate, or 2 burn at once or something.

The stove really behaved like a pellet to me in terms of the forced-air flames coming off the bottom of the briquette. The inventor mentioned one notable difference here is the simplicity of the control - there is no feed rate, no auger, as it's gravity fed, but it appears from the literature there is some measure of control (combustion fan speed would dictate oxygen supply and how fast the logs burn down).


An important detail is this uses 4 inch pellet vent.

Next up is the Kd3 by Unforgettable Fire. This is a woodstove with downdraft gasifier, and the gasifier put on an impressive show.

First pic has dirty glass up top (more "R&D" to be done here, like adding an airwash system), 2nd pic is better-



The Kd3 had a TEG which was water-cooled. I was curious about the water aspect here, and the general idea was this is a space heater, with a little hot water for some light-duty applications (in-floor radiant heating for a room?)
It uses 4" pellet vent.

Also in the corner, another stove this same vendor produced a while back - the Kimberly Stove - note the small silver stove in the center of this image-

This uses a 3 inch pellet vent. Page: (broken link removed)
That really got my attention more than the TEG stove they were demo'ing. Except for the $4K price tag....

Next up is one I found fascinating, the Deutsch-made E-Stove by Thermoelect GmbH (imported by Wittus-Fire by Design, Pound Ridge NY, www.wittus.com)
This is a micro CHP system that burns cord-wood. The brochure lists 10-20kW for central heating and DHW, up to 250W thermoelectric generation.


It's a downdraft gasifier with a metal "mushroom" in the bottom of the firebox for the smoke to shoot down into the secondary combustion chamber:


Primary air comes in through the big holes at the top of the firebox, and secondary air comes in just inside the bottom door. The unit is designed to
sit in a living area, with the brochure depicting the unit in an exploded view diagram as if the panels were interchangeable or selectable... never did
ask about that.

The firebox holds around 5 kilo's, so not a lot of wood at once, although something doesn't sound right about that - at least with wood briquettes I
bet you could fit much more than that

(more-)

 

[spirilis]

The "Lumbernator" was burning but I never got around to asking questions... all I recall was someone pulling the side tray out, with a burning log,
and letting a bunch of smoke into the tent.

I thought it was a frightening contraption actually. Something about aluminum foil tape everywhere.....

I did not get a pic of the GWU Continental, which is basically an Englander NC-30 with a few water-cooled TEGs sitting on top. It's just a research
platform to teach thermodynamics and thermoelectrics to students.

If you looked at the list of contestants on (broken link removed to http://forgreenheat.org/2018-stovedesign/award.html) ... two contestants probably look scary:
The Downdraft Rocket by ASAT, and the Wiseway by Hi-Z.


The Downdraft Rocket is a rocket stove built of metal, with a vertical feed tube which features metal fins to keep the feeder tube from getting hot
towards the end of a burn and back-drafting. The combustion chamber at the bottom features the TEGs and a large circular fin heatsink, no water
cooling here.


The big metal barrel is a traditional rocket setup, and it has a plate on top for cooking. I asked about venting the rocket into a thermal mass
bank as is often done with Rocket Mass Heaters, and the inventor said this wasn't his intention - this rocket stove is meant to be a short-term
cooking stove for applications in remote areas of northern China, where they may live in yurts or other difficult-to-heat locations with limited
fuel supply and space. This was vented by a 6" flue from what I gathered. It's an ugly prototype, a commercial implementation would be redone with stainless steel most likely.



The Wiseway is based on a non-electric, gravity-feed pellet stove by US Stove Company. I didn't realize they had this, and it's EPA certified + UL-listed. http://www.usstove.com/index.php?route=product/product&product_id=3466



This inventor is not an expert in stove design but cut apart the WiseWay, removing the window, and routing the exhaust between the 1st and 3rd
bend (counting from the bottom) through a circular TEG array with cooling water.

Experimenting a bit further with the design, he tried cutting a hole in the 1st bend and sticking a pipe down in there to admit secondary combustion
air, which is pre-heated by having the tube stick in a foot or so, down to where his finger is pointing-


Image of the secondary air intake tube with the imperfect hole illustrating the gates of hell:


This really improved combustion efficiency.
(edited-)
This stove netted the lowest Carbon Monoxide numbers for all the thermoelectric generating stoves, although at least 1 of the non-TEG automation stoves netted lower CO numbers than this.

The combustion chamber cover was off when I took this pic, so I saw some sparks coming out-


The inventor wasn't quite sure about the output but estimated ~120 watts at that moment.
(edited-)
2nd test was actually 130W.

It was keeping a 12V lead-acid battery charged and running
some LED lights:

That's also his radiator in the lower right, and he's looking to borrow a larger barrel storage system going by Tuesday when the judges make their final call (to get some more power out of the TEGs).

The unit has some off-the-shelf inverter/charge controller system he uses to provide AC and 12V outlets on the back:


(more-)

 

[spirilis]

Finally we have Maine Energy Systems with their advanced pellet boilers. They had a homeowner-grade pellet boiler and forced-air furnace on
display but not operating, however the demo for the show was their Pellematic e-max stirling generator boiler:


Shown here is the main boiler system with a helium-filled, hermetically sealed Stirling engine on top.
The stirling engine receives cool intake water from the hot water storage system, and heats it up a bit. I'm not 100% sure where that goes - if it's
in series with the main boiler system or what, but the boiler is a 60kW (~200K BTU) monster for commercial applications.

Showing the top of the boiler combustion chamber and the hot-side of the stirling engine:



System is cranking out ~1.6kW right now:


They had a hot water tank ready for this demo-


Plumbing into the back of the boiler (closeup)-


To run the demo, they had 4 air handlers outside the tent venting off heat-


Better picture of the back of the unit-


6" flue for all those pellet boilers btw.

Picture of my son posing in front of all 3 of their units-


He was just about spent and ready to go play on the Carousel at the Mall by then

Picture not taken but was present, was a Tesla Model S charging off that boiler, although I don't know if it was actively charging at that time since
the boiler was only putting out less than 2kW.

Minor facts about their other pellet boiler to the left, which is more like a 20kW unit - It provides domestic hot water and has its own tank, can be used during the summertime (only heating the DHW) from pellets. They estimate typical usage for 12 months is ~6 tons of pellets for that unit. Supposedly it's OK'd by insurance companies as your primary heat source despite being solid fueled. All the MESys pellet systems support automatic ingesting of pellets from a large bin system by supplying air in one tube and receiving pellets in another tube.


Other "stuff" I noticed-

Random hearthstone stove running, I guess for testing fuel or maybe it's an EPA certified "control"-


Masonry Heater Association had a unit built for display, not fired-


I never got a chance to chat with these guys but this was fascinating and bears more discussion- OekoSolve.com


The OekoSolve is an electrostatic precipitator, which fits inline with your flue, draws about 30 watts when active (0.7W standby) and
actively pulls fine dust particulates from your flue gasses. Designed for up to 50kW (170K BTU) and mounted either behind the furnace or at
the end of the smoke stack, it produces ~15-30 kilovolts to clean up the PM emissions. This is really good news for those wood burners who have
to deal with local regulations and burn bans - if technology like this could make a burner "exempt" from the burn bans.

It can be cleaned by a chimney sweep or "optional automatic scrubbing" available.

Among the tables full of literature, I found this interesting enough to grab its literature-


The Sonnen is a Tesla Powerwall competitor using LiFePO4 batteries inside for backing up solar residential systems. Literature claims warrantied to
15 years / 15,000 cycles fyi.

(more-)

 

[spirilis]

Miscellaney:





^ these looked like particulate matter filters but.... no context where from

 

[spirilis]

So there is a panel of judges and technicians who are analyzing the flues of these various stoves for metrics such as CO, particulate matter, temp, etc... along with the TEG metrics these will be used to judge the stoves on Tuesday, ~2-3:30PM.

 

[BrotherBart]

Many thanks for the info and pics. Really hated not being able to be there this time.

 

[spirilis]

Many thanks for the info and pics. Really hated not being able to be there this time.

Still going 'til Tuesday

 

[begreen]

Yes, thanks for the detailed posts. I too would have liked to have been there for a few days to soak up all this new info. The VcV intake valve intrigues me with its simplicity of design. It will be interesting to see how it tests. I'm surprised Woodstock didn't participate, they did well last time.

 

[kennyp2339]

excellent recon mission

 

[spirilis]

Ok, didn't realize MESys's Pellematic is actually an imported Austrian product-

http://www.okofen-e.com/en/pellematic_e_max/

 

[jetsam]

That is SO COOL. A pellet fueled Sterling generator =D

 

[begreen]

Ok, didn't realize MESys's Pellematic is actually an imported Austrian product-

http://www.okofen-e.com/en/pellematic_e_max/

Yes, MES is in the biomass heating business. They are providing a European style bulk delivery service for pellets and they sell the boiler or furnace plus storage equipment to complete the system.

 

[begreen]

Borrowed picture from Green Heat Alliance of Olympia's new colored, powder coated chimneys that were shown off at the challenge.

 

[heatwise]

Wonderfull rundown of the stoves. I had the pleasure of attending this year after finding about it on this site. Seeing the stoves and chatting with the inventors and engineers was priceless. I wonder who won the competition this year. Thanks again for the through post.

 

[begreen]

This is from their Facebook posting:

The judges finished scoring and the awards go to:

First Prize for automated stoves: Wittus. Great performance on emissions, efficiency and safety.
Second prize for automated stoves: SBI. Fully automated stove that may only cost $500 more than if it were non-automated.

First prize for thermoelectric stoves: Wittus; The highest electric output up to 250 watts, and more than 300 watts when used with densified wood logs.
Second prize for automated: Hi-Z. Produced more than 100 watts and good PM reduction.

Innovation prize: SBI, for simplicity. The stove uses only one thermocouple and one other sensor and successfully navigated a very tough fueling protocol that included reloading based on consumer habit.

People’s Choice Award: 509 Fabrications.

 

[spirilis]

Had an email convo with Fred Leavitt from the WiseWay team, he suggested a few details I've edited in my original posts.

@begreen - Hi-Z actually got 2nd place in thermoelectric, this was a typo in the original FB post

 

[Easy Livin’ 3000]

Was that guy from New Zealand around?

You remember, the one who got real defensive when bholler asked him all the right questions a year or two ago.

I honestly hoped that he'd succeed, because his story was a good one.

His defensiveness made me skeptical.

 

[spirilis]

Was that guy from New Zealand around?

You remember, the one who got real defensive when bholler asked him all the right questions a year or two ago.

I honestly hoped that he'd succeed, because his story was a good one.

His defensiveness made me skeptical.

I know VcV was from NZ but I never got a chance to chat with them.

 

[Easy Livin’ 3000]

I know VcV was from NZ but I never got a chance to chat with them.

I bet that was him. I recall it was some sort of retrofit add-on that somehow got air in through the flue and increased the burn efficiency. Last I heard, he had partnered up with a US stove builder to try to build a stove around it, integrate his thing into the design.

Thanks for your write-up. Looked like a cool event.

 

[wooduser]

Isn't this a roadmap to the future of government regulation? I'm supposing that environmentalists can hardly wait to write rules requiring greater cost and complexity in wood stoves --- all without passing any new actual laws, at least on the Federal level.

 

[Easy Livin’ 3000]

Isn't this a roadmap to the future of government regulation? I'm supposing that environmentalists can hardly wait to write rules requiring greater cost and complexity in wood stoves --- all without passing any new actual laws, at least on the Federal level.

So I think you should have a better strategy.

I am as passionate an environmentalist as they come. Also one of the most passionate wood heaters. These two things couldnt be more compatible.

Unless you declare them your enemy, which it sounds like you already have, environmentalists can be easily convinced that wood heat is a good thing.

Using the term environmentalist as a perjorative will not get you far.

And, are you sure it's not the energy and utility companies responsible for pushing the agenda your dumping on "environmentalists".

 

[spirilis]

I get the impression from the pics on Alliance for Green Heat's facebook (espec the EPA employees visiting the 1st day) this is an attempt to bring the industry and tinkerers together with the regulators to discover what is possible and what can be appropriate with current technologies.

I can't imagine Brookhaven Natl Lab's readings from the various flues will be discarded. Regulators now know what's possible here and what might be reasonable.

 

[georgepds]

Re...Isn't this a roadmap to the future of government regulation?

Huh? I thought it was all about heating better with wood

 

[bholler]

Isn't this a roadmap to the future of government regulation? I'm supposing that environmentalists can hardly wait to write rules requiring greater cost and complexity in wood stoves --- all without passing any new actual laws, at least on the Federal level.

No this is about innovators in the industry showing off and testing their products. If you knew anything about modern wood stoves you would know that with these regulations they have inproved in almost every way all while keeping inflation adjusted pricing in the same general range.

 

[SpaceBus]

I'm learning more about solid fuel stoves every day. Today I learned that electricy can be generated by solid fuel!