EPA Announces New Regulations for Woodstoves

I'm inclined to think the Rocket Mass Heater could, but the batch rocket won't. Both these stoves won't emit droplets of tar, but the crux here is fly ash. There are bound to be very fine ashes in there as well, and namely the batch rocket is burning fuel at a racing pace. The regulations does say "per hour" instead of "per weight of fuel" so this is definitely not good. Somebody has to start investigating the possibilities of a simple static dust extractor. Maybe a swiffer?

None of these stoves could have low exhaust temps. Once the steam starts to condense the liquid droplets would skyrocket!

"Fine particulate absorbed by breathing has been linked to heart attacks, decreased lung function and premature death in people with heart or lung disease."
It sounds like the article is talking about the hazards of cigarette smoke.

I've got some numbers from the testing done at the Decathlon, but I'm not sure how to interpret them. They are in g/m3 and I have no idea how to translate that to gph. Not only that, but the larger problem, which is really the big stumbling block to bringing any rocket heater to market in the US, is that there is no accepted test method which will work with a rocket heater. There are two accepted methods, the masonry heater one, which starts the test 15 minutes after lighting a cold stove, and the EPA method 28 for wood stoves, which starts the test 30 minutes after loading on coals. Neither captures the peak burn of a rocket, and both run for too long which captures the coaling stage rather than the burn.

All that aside, a snapshot from the peak of a burn in my Walker Stove, using Peter's batch box, shows a number of around .02 g/m3. Maybe someone can convert that to gph for us.

The consensus was that any heater with such high gas velocity through the ash bed was going to do poorly on 2.5m particulate. So, I'm under the impression that rockets won't do very well in this category. This same characteristic was noticeable in the measurements on the Wittus entry. It did very well on efficiency, but not particularly good on emissions, due to high gas velocity downwards through the ash bed. The new box stoves do very well on this measurement since when shut down and burning on secondaries and a cat the ash bed is very, very still.

I had a chance to speak to very knowledgeable folks on this matter, and contrary to what I thought going in, the 2.5m particles are inorganic and cannot be consumed in the fire.

Matthew said: "Lots of talk about electrostatic filters, as Peter mentions, and also just simple physical filters. I wonder if a fiberglass furnace air filter might be used in a large enough CSA filter plenum that it wouldn't present too much resistance to the flow."

Filtration should be a viable solution, and the fact that RMH exit temperatures are relatively low makes this a practical one. I would guess that a furnace air filter would not remove 2.5 micron particles. However, the air going into car engines is filtered free of micron-sized particulate matter using folded paper filters. Matthew, perhaps the people you talked with were not considering paper or other simple filters (e.g. oil) because of the higher exit temps of most wood stoves?

Nah, EPA probably wouldn't go for a paper (or oil bath) filter either.

obob

I wonder if one could utilize the TEG technology to create a permanent electrostatic charged filter at the exhaust. Something that would generate ions upstream and pull ionized particles out of the gas stream by forcing the gas through a stack of grounded stainless plates prior to exiting the system. Just wipe the surfaces down once a week or whatever to expose the metal again. Hell, the whole system is grounded so all you would need is the ionizer and the particles should want to stick to the bell or duct on their own.

I know TEGs are very low voltage but some electronic wizard could probably figure out how to make an ionizer with one. I wouldn't want to have to plug in my rocket stove...

As for slowing the stack speed down to precipitate these particles out that will not work. You have all seen dust in a sun beam and the particles are just sitting there in the air. Well this size particle is actually smaller than most you seen in a sun beam. They will settle out of dead calm air but it is a matter of hours to weeks for this to happen. Right now the smog that covers Salt Lake City and the whole area around it is mostly made up of these particles. Out of a rocket stove because of it complete burn these particles will be NON-combustible compounds. The wood contained trace amounts of iron, copper, calcium, silicon and so on that is what makes up these particles.

Now you can use Hepa filters but the expense would be huge. Passive electrostatic filters might work given the high volume flow of a rocket stove but would need regular maintenance. Active electrostatic filters are probably the best bet. Likely for ease of design it would be better charge a battery with your thermoelectric modules and then run the filter on battery power. One of the gains from this is after the fire goes out and things cool enough the circuit can be designed to reverse the polarity momentary to the electrodes fully cleaning them letting the dust fall to a collector bin. A batch fed RMH with fairly short run times would be ideal for this type of filter. Now for best operation you likely will want to remove as much courser fly ash from the stack as you can ahead of this filter.

Ha! I still have the 437w Arctic Web TEC that I ran on my AMD Athlon64 3800x2 processor. Fed the TEC 15v, ran water through two car heater cores and a radiator fan running on 5v kept the processor at -15°C at idle and 0°C under a fully loaded 1Ghz overclock (2.6Ghz operating frequency).

It's interesting, with rocket stove tech seeming to be on the exact opposite end of the technology spectrum when compared to advanced overclocking and cooling - with TEC cooling being rare even within the overclocking culture - that I'd run into another TEC/Overclocker on a wood stove forum.

But sorry for the thread hijack.

Unfortunately TECs are unbelievably inefficient and the the voltage is determined by temperature gradient (not total temperature). One would assume you'd simply stack the TEC on top of the barrel where it's the hottest - but then you'd simply melt the solder off the TEC and it would fall apart. Even if it could withstand the temperature, the opposite side will need to be actively cooled - which will more than likely use most of the power the TEC produces.

I'm not sure how much power is needed to run an electrostatic filter (I imagine it's not much) but the cooling overhead would have to be taken into account.