Steve Farmer

Even in arid land you can get wood into the ground using nature rather than diesel. Plant support trees. Support trees are so called because they dont necessarily give food or firewood but enhance the environment thru giving shade and biomass so you can then plant trees that you can live off. The nitrogen fixing legume trees are good as they can grow fast. Rather than hauling in heavy machinery, haul in some water and kick start some shade trees.

Mike Homest wrote: I expect it to be in the 70-100 kg area. So uphill might be a challenge with it?

I guess at least double that.
An e bike and solar panels on trailer roof could be a nice upgrade.
I'd love to have something like this but living at sea level on a volcano,  everything is uphill so for me would have to have a motor.

Devan Wickland wrote:If rather then drilling, you collect rainwater, does that deplete the streams and rivers downhill???
Thanks!!

Depends. From observation and guesswork, most of what falls on my land evaporates or runs to gullies that lead to the sea. So im happy to take it. If you live well inland  and your downhill neighbours are making sensible use of your runoff then you need to be making even more sensible use of it. If you establish soil and shade then perhaps taking the runoff now will benefit your downhill neighbours in a year or two. On balance, if you can use it productively, and are allowed to, then take it.

Devan Wickland wrote: I wonder what other people think of drinking up the underground water, especially in the desert... Is it inherently unsustainable to do this?

It's not something i would do. My preferred approach is to use natives or trees from other parts of the world with similar climate. In this way to bring shade and organic matter using only what falls from the sky. However, if the idea is to make a quick start to get this shade using groundwater, and then a year or three later stop using groundwater, that could be sustainable.

Glenn Herbert wrote:And the engine analogy breaks down due to the fact that the fuel combustion is only intermittent, and designed to occur so fast that there is no time for significant radiation or conduction to cool it. The RMH configuration has the gases in contact with the core walls while burning, and turbulence needed for best combustion would bring much of the gas into contact with the walls at some point. You may get 1300+F in the heart of the riser, but much of the gas will be lower temperature, and will definitely not reach the fairly uniform 1600-1800+F that clean J-tubes are capable of to destroy the last pollution compounds.

(Ernie and Erica made statements years ago about 1100F, but more recently they are claiming well over 2000F maximum, with a caution to not exceed 2300F so that NOx pollutants are not created.)

The exhaust manifold is getting no break from combustion temps. Look at the egt gauge of a V8 turbo diesel. 1000F+ but the manifolds and turbochargers can last for decades.

Bruce Woodford wrote: flame path temps are far higher than the actual temperature of the core which contains the flame.  I know that there is a temperature difference of at least 325 degrees F between my flame path in the heat riser (at least 1225F) and the hottest part of my burn tunnel (less than 900F).

Yes this is the critical point that seems to be missed by the "Don't use metal in a RMH" dogma.
Internal combustion engines are made of metal and can last for decades.

Satamax Antone wrote:The most metal in your engine doesn't go much over 100 celcius.

I don't dispute that, however *some* of the metal, especially in the cylinder and
exhaust immediately behind the engine gets way above that. The water cooling keeps the average heat of the engine head down but it also means the materials in the engine are dealing with massive variations in temperatures eg fuel air mix combusting at thousands of degrees just a few millimetres away from a water jacket at just below coolant boiling point. Are you sure that my multi layer steel head gasket isn't seeing higher temps than the materials a rocket stove is made from?

My turbo diesel truck is 27 yrs old, has done 490,000km and has its original exhaust manifold, which at an educated guess is cast iron. Do rocket stoves get hotter than turbo diesel engines?

$ per watt is the important metric here. 12v or 24v doesn't  affect the value. $1 per watt is twice as expensive as $0.50 per watt.