Podcast 241 – Ernie and Erica on Rocket Stoves Uses and Efficiency

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It’s time to talk about rocket stoves mass heaters again! We haven’t had a podcast with Paul, Ernie and Erica since last year, after the GIGANTO rocket stove workshop. After they recorded that podcast they were actually inspired to go out and do some more fire stuff, so they can talk about that here. But FIRST, they talk about the Kickstarter.  (If you haven’t watched the video there, just stop and go there, now. It’s funny.) The goal has been met, so the 4 DVDs will be produced, but Paul isn’t sure how many extras he’s going to press, if he even does that at all. (So, have you bought the DVDs via the Kickstarter yet? Have you, huh?)

If the Kickstarter can break $100,000 (that’s just 1,000 people buying 4 DVD sets) then Paul will be able to move forward with his plans for world domination by saving the world. (He will be able to finally buy some land in Montana.) Erica points out that Paul is the one that got Caleb, the hot water dude, together with her and Ernie for this workshop (this will be the boom-squish DVD), and that may never happen again. Erica thinks the most popular DVD will be the fire science one, because the stuff on there is so incredibly cool you want to show it to your grandchildren. Paul says the vast majority of buyers are getting all 4 DVDs, with the most popular single DVD being “Sneaky Heat” and the next most popular being the Fire Science. Erica is relieved that the least popular single purchase is Boom-Squish, because it really IS that dangerous. That video is going to have lots of tape of people saying just how incredibly dangerous steam can be. Erica tells Paul he really needs to video his neighbour who actually was present (but not too close) at a steam explosion, for inclusion in the video.

Ernie wants to talk about cookstoves. Last fall at the end of the workshop, they ran an experiment pitting a J-tube rocket stove against a propane turkey cooker. They put the exact same pot on both stoves, half full of water. They lit both stoves at exactly the same time, so the rocket stove had to go through its warming up process before it could really start putting out heat. The propane cooker won by 3-5 minutes. This was a big surprise, and a huge disappointment. (Ernie later notes that they had used wet pine sticks as the fuel in their overconfidence.) Erica wishes they had weighed the propane canister to see how much fuel they went through, because boy that thing was roaring. It was very loud. Then they tried it again, this time having the fire going on both stoves and put pots full of water on at the same time. Also, this time they used hardwood in the rocket stove. This time the rocket stove won. They noticed that the propane stove had a pot skirt and so they made some modifications to the rocket stove, despite severe exhaustion (under extreme pressure from some gigantic guy with a video camera) and the third time the rocket stove boiled the water in less than half the time of the giant propane turkey cooker. They note that they were burning scrap wood from Caleb’s lumber, and the turkey cooker was blasting through massive quantities of very dense fuel.

Paul notes that if they had sunk the stove into the ground, or extended the sleeve, or improved the “tinfoil hat” that they used in the third trial, they could have improved the performance even more. Ernie and Erica note that they could have used more insulation. Then, Erica points out that for actual real life cooking, as opposed to competitive pot boiling, you’d probably want a smaller system, not a more powerful one. When that same stove was used to prepare food for the 40 people at the workshop, the chef needed to do many things to try to moderate the heat output downwards.

Ernie moves on to the coolness of melting carbon steel with a rocket stove, which is also going to be in the Kickstarter DVDs. Mark Vander Meer is a blacksmith, and he looked inside the stove and said “that looks as hot as my forge!” so they put some steel in there and lo and behold it got red hot. In 30 seconds it would get “cherry red” where you could pull it out and pound it or pull it into a new shape. Ernie figures it was running at 2100 degrees Fahrenheit. Mark was amazed that they could achieve forge temperatures burning scrap wood without needing a bellows. A rocket forge is now in the works.

Erica now has a new book(let)! She’s made a booklet on “The Art of Fire,” which she describes as the stuff of the Fire Science Theater “but with even less science.” It’s got a lot of good basic advice about managing fire, from cook fires built while camping to fine tuning a wood stove. Available now on the digital market.

Erica recently posted to permies.com on the greenhouse thread where she has been sharing some things that she’s learned about using wood heat to warm a greenhouse. Ernie points out that if you build your rocket mass stove into the base of a raised bed, nobody will be walking on it. Erica is looking for people to work with her with an eye towards a future publication, so if you are building a greenhouse, or you have a greenhouse and want to heat it with scrap wood, go check out the thread. You could get a sneak peak at their well-researched greenhouse heating stove plans.

Ernie and Erica are looking for minions! If you would like to learn to build rocket mass stoves to Ernie’s specifications, and you’re really serious about learning, you could learn from the master (and mistress). You need to be cool with following their advice, at least for the first several months. Erica notes that they run into trouble with people who read Ianto’s book where it says that you can have the chimney exit your house low (and look like a dryer vent). She says that WILL work, but only if that particular house doesn’t have this desire to suck air in from openings near the ground after it has been warmed up, say, by your rocket mass heater. This is the sort of thing they have learned from experience and they would like to share this knowledge with others, but it’s nice to have your experience acknowledged. So, if you can hold off on expressing your own fabulous ideas (that you developed after doing some reading and thinking, but have not actually, you know, built yourself) until after you’ve learned the Ernie and Erica way of doing things, they would love to teach you. Paul would love for someone to live in a teepee outside through the winter, heated only by a rocket mass stove, so he could video that.

You can discuss this podcast on this thread at Permies.