Rocket Mass Steam Engine?

Question for the energy folks:

I’m mostly a carpenter, designer, craftsman type. I have a large wooded lot and enjoy firing ceramics. I’m building a small cabin and thought briefly about alternative energy but will probably bring in gridded electrical power.

I really enjoy the idea of the rocket mass heater. And when I started laying out the foundation for my ceramic kiln, the thought came to me, I could have two incredibly power and moderately large wood burning furnaces, there must be a way to utilize them for electricity..?

I’m no engineer, so do the intelligent people here, have an option or thoughts on converting heat from RMHs or wood kilns into electricity?

I have two general options: one it should be able to do it while running it’s normal function. Such as heating a home in the winter or firing pottery.

And two, it would probably need to be relatively easy to “attached” or modified to the existing “furnace”. What came to mind was a stream turbine/generator that could charge a battery then be distributed to power electronics.

I know not everyone has a passion for ceramics. But one of the biggest obstacles with solar is the lack of energy from the sun during winter, which if electricity could be converted from a wood stove or RMH during those same winter months…maybe, just maybe, right?

That’s the extent of my knowledge. If someone who knows more than me thinks that’s possible, please let me know what information I should be reading up on or devices that could be considered and adapted. I find this extremely exciting, but if I’m high on my own ignorance of the matter, feel free to bring me back down to earth.

Humbly,

I think the bottom line is that it is technically possible, but would be dangerous, troublesome, difficult, and much more work than most people realize. One pound of wood could generate 3.38 horsepower hours of work. A steam locomotive, as highly refined as they were, achieved about five percent efficiency. A small engine would likely be much, much less efficient. Then converting it to electricity in an alternator would be about 70-80 percent efficient. Using a lithium battery to store and use the energy would be about another 78 percent efficiency. You can see how things add up against you.

I have my high pressure steam license and while not an engineer I know; from an operational standpoint, it is very dangerous.

The problem is, there is never any pure steam in pipes, as it moves along a pipe, some of that steam is converted to condensate and that can easily lead to a steam or water hammer, or what is called a "slug" in normal boiler speak. It is destructive at best, and explosive at worst.

As Jordan mentioned it is inefficient too. I love steam and all that it can do, but I sadly know the more efficient it becomes, the more dangerous it becomes too. As steam becomes viable, it is pressurized so that it increases the boiling point of water, but then one crack can send the pressure to zero, and the boiling point from 600 degrees down to 220 in an instant, making all of it steam, and then an explosion. It takes longer to read that sentence then it happens in real life, and it happens all the time, like last month killing 3 people in PA. To make redundant safety systems, it just becomes unfeasible at that point for a DIY build.

But then where does it end? You need back up of back up make up water systems, and that requires back up power for the pumps and a reliable source of water... and plenty of it because evaporation is high. And getting wet steam converted to dry steam by way of superheaters is not a quick system to build either. Even if you can produce meaningful quality steam, a DIY regulating system to keep that generator spinning at exactly 3600 RPMS is not easy either, and just 1 rpm off and your hertz, also called frequency, will be off ruining expensive electric devices and motors.

It really comes down to this; it is easy to make steam and get work from it, but it is very difficult to make dry steam that can do a meaningful amount of work, and especially so at the tight parameters that power generation requires.

My life is power generation for the grid, and once worked in renewable energy at a boilerhouse squeezing 103,000 pounds of water at 750 psi to generate 31 megawatts. Still there is no way I would even ATTEMPT to make my own steam power system for my home.

I agree with the cautions above. I've worked in the power generation field. I wouldn't go anywhere near a homemade steam boiler. No thank you!

Dave, I think you should be looking at Stirling engines instead. Very safe, converting heat into rotational torque. I have seen old-time models demonstrated in museums, with a water jacket as the working fluid. Seriously cool devices!

I just have to post these Mythbusters exploding water heater links. Just so cool to watch (from far, far away).

Much better to look at wood gas.....

I built a gen that uses charcoal to run my generator, to charge batteries.      I abandoned this when I found cheap solar panels....

But I have the materials to take this to the next level, just the price of gas is too cheap for me to finish it.




This is a proven method and if you need help  the site  driveonwood.com   is where you can really get help to build it.

I also think that a Stirling engine generator would be the way to go. Take a look a the ones they have at Tamera in Portugal, for a sense of how they work and scale of their machine/watts output. Since the Stirling is an external combustion engine, you are only using (waste) heat, which you have in abundance, rather than fuel combusted solely to power the engine (by expansion from combustion, as in the wood gas fueled engine example).
With the ceramics kiln, you likely have a surplus of waste heat from normal operation to also run a Stirling engine generator, and then some. You might also think of how to direct some/all of this waste heat to a mass in your living space.
With the rocket mass heater, it might be the opposite, feeding more fuel then your heating load in order to also run the generator. Either as longer duration, to meet your electric demands, or possibly hotter to supply heat for both?
I think there's some real potential for a RMH barrel-top Stirling engine generator that maybe also makes domestic hot water... Hot end of the engine is on the barrel, cold end of engine is cooled by "hot water" circulated from water heater. (atmospheric system, not pressurized, no "boom-squish"!)

Dave Black wrote:Question for the energy folks:

I’m mostly a carpenter, designer, craftsman type. I have a large wooded lot and enjoy firing ceramics. I’m building a small cabin and thought briefly about alternative energy but will probably bring in gridded electrical power.

I really enjoy the idea of the rocket mass heater. And when I started laying out the foundation for my ceramic kiln, the thought came to me, I could have two incredibly power and moderately large wood burning furnaces, there must be a way to utilize them for electricity..?

I’m no engineer, so do the intelligent people here, have an option or thoughts on converting heat from RMHs or wood kilns into electricity?

I have two general options: one it should be able to do it while running it’s normal function. Such as heating a home in the winter or firing pottery.

And two, it would probably need to be relatively easy to “attached” or modified to the existing “furnace”. What came to mind was a stream turbine/generator that could charge a battery then be distributed to power electronics.

I know not everyone has a passion for ceramics. But one of the biggest obstacles with solar is the lack of energy from the sun during winter, which if electricity could be converted from a wood stove or RMH during those same winter months…maybe, just maybe, right?

That’s the extent of my knowledge. If someone who knows more than me thinks that’s possible, please let me know what information I should be reading up on or devices that could be considered and adapted. I find this extremely exciting, but if I’m high on my own ignorance of the matter, feel free to bring me back down to earth.

Humbly,

HI Dave, So if you want to go the fire to electricity route your best bets would be either the stirling route mentioned above or the thermo voltaic route. Steam engines for many reasons are a non starter at the home scale. Also mentioned above is the charcoal gasifier route which is by far a more efficient solution. I have spent quite a lot of energy on that technology and it certainly works but lately  find that cheap solar panels, even in winter, are a far more efficient solution for most cases.
CHeers,
David Baillie

If you want to get into steam safely then forget about water boilers and use thermal oil and thermal oil steam evaporators. The technology is out there off the shelf and is used in the commercial bakery industry.

r john wrote:If you want to get into steam safely then forget about water boilers and use thermal oil and thermal oil steam evaporators. The technology is out there off the shelf and is used in the commercial bakery industry.

Very interesting! And it makes sense, from a large scale point of view.

Any thoughts on how you would build a backyard system that mirrors this technology? That would be seriously cool!

Douglas Alpenstock wrote:

r john wrote:If you want to get into steam safely then forget about water boilers and use thermal oil and thermal oil steam evaporators. The technology is out there off the shelf and is used in the commercial bakery industry.

Very interesting! And it makes sense, from a large scale point of view.

Any thoughts on how you would build a backyard system that mirrors this technology? That would be seriously cool!

Yes, from what I could find in a brief search it seems interesting, but I'm not understanding how it would be much safer? Steam is still steam whether heated directly by flame or by heating oil which then heats the water. And it looks like the oil system (just using oil to move heat, not to boil water if I understood it correctly) was ten percent less efficient (I would imagine even more so if using it indirectly to boil water). Is it possible for a breach or explosion of some sort to cause the oil to burn or explode?

When I was researching this,  the boiler design I saw was pipes inside a boiler  that if the pipes broke the boiler would contain the steam.


This is the web site I went to when I was investigating steam ->

http://kimmelsteam.com/brown.html

It looked like he had the safety issue in hand...

Here in Florida you have to have the boilers inspected at regular intervals as I recall,

The "Strange Engine" may be another option

https://www.youtube.com/watch?v=Ia4dN0fem6s
https://www.youtube.com/watch?v=VcebI0ez0Js
https://www.youtube.com/watch?v=ugk819GQ6Z0
And mostly:

Douglas Alpenstock wrote:

r john wrote:If you want to get into steam safely then forget about water boilers and use thermal oil and thermal oil steam evaporators. The technology is out there off the shelf and is used in the commercial bakery industry.

Very interesting! And it makes sense, from a large scale point of view.

Any thoughts on how you would build a backyard system that mirrors this technology? That would be seriously cool!

The reason I suggested the bakery systems is because it is small scale, Think of France and a bakery on every street corner. The biomass boiler heats thermal oil instead of water. This hot oil is then used to heat the bread oven at the right temperature. Obviously this is a very dry heat unlike gas so the hot oil is also used to generate steam using a thermal oil steam evaporator so that steam can be injected into the dry oven to produce the perfect cakes and pastries.

I would not suggest building your own backyard system as hot thermal oil is normally around 230C and can cause serious damage to humans. Just think of working with a hot chip pan full of oil. Please leave it to the professionals