Marcus Zed

Jeremy Cash wrote:The best thing to do with a good theory is test it. Take lots of pictures, documentation, etc. and share your findings with us.

I would if I had a greenhouse, or a place to build one.

C.J. Murray wrote:I would not recommend this for the following reasons:
1) People gotta be in the greenhouse at some point and there is no way to guarantee no CO was produced along with the CO2 and water vapor.
2) Plants need oxygen too, not just CO2.
3) The water vapor is gonna condense on everything and it'll be a rainforest.

Good points. The first response I have is that I am not immagining a completely sealed greenhouse. It would be normally ventillated, only with the addition of a passive one-way vent to keep the pressure equalised if the heater was burning with the service vents closed.

The CO point is a particularly good one. I personally smoke tobacco, and hope to one day heat and cook solely with wood/biomass, so I am not hugely fussy about small ammounts of CO exposure. The key would be what concentrations we are talking about. I have CO detectors in my current home in addition to smoke detectors. They are relatively inexpensive and can be run on wall current or batteries, it would probabally be a good idea to have something like one of those on my exterior "control panel".

I like the example, Monte. Kind of a non-sheltered earth-tube arrangement.

Usually when someone says "geothermal", I think deeply-drilled tapholes; which is a pretty resource-intensive proposition.

So, in all the rocket stove/RMH discussion and documantation I have seen, people keep making the point that the exhaust is "mostly just water vapor and CO2".

So, if you are using an RMH to heat a greenhouse, why vent the exhaust to the outside? Isn't warm, moist, CO2-rich air pretty much perfect for plants?

Of course, you would have to have an exhaust vent somewhere in the greenhouse in order to equalise air pressure with the outside for the RMH to draught.

Also, the atmosphere within the greenhouse would be bad for humans/animals, so you would want to be able to read the interior temperature, light the RMH and add fuel, lower sunshades, and controll any watering aparatus without going inside. You would also have to vent the air in the greenhouse before entering to do any work.

Any other problems with this that I am not thinking of?

So, I have put a bit of thought into the concept outlined below, and ended up posting it in another thread a couple of days ago. Since there hasn't been any movement on that thread, I am re-posting it as a seperate topic because I very much would like to hear any comments.

I realise that air conditioning an off-grid home might seem frivolous to the most committed permaculturists out there, but I am trying to think of ways to make more sustainable living appealing to a wider segment of the population who might not be willing to sacrifice comfortably interior temperature (especially in hot climates which try the limits of passive cooling).

The orrigional thread-starter's question was about using a rocket stove as a heat source for an absorption chiller.

Marcus Zed wrote:I have been thinking about this recently for my own use, and here is what I came up with:

An absorption chiller (water/lithium bromide) DOES NOT USE HEAT TO COOL, it uses vacuum to evaporate the refrigerant (water), a dessicant (lithium bromide solution) to absorb the water vapor in order to maintain the vacuum, and heat to re-concentrate the dessicant by boiling off the water.

In commercial systems, all of this usually happens simultaneously (so that you need heat to run the system as well as power for the pumps), but there is no reason that it needs to.

If you retrofitted a small absorption chiller with a VERY LARGE dessicant storage tank and very large used dessicant tank, you could use heat whenever it was available to reconcentrate dessicant, even if your system was not cooling at that time. This heat could come from whatever stove you use for cooking/baking or other process. Because the system is primarily plumbing, you could put the cookstove, dessicant boiler, and dessicant storage tank in a seperate building with little difficulty, thermally isolating it from the building you are trying to cool. The commercial systems I have looked at feed dessicant at low pressure, so elevating the bottom of the tank a few feet above the evaporator could give you all the pressure you would need.

In order to actually run the evaporator and circulate the chilled water requires electricity. If you found appropriate DC motors, this part of the system could be run directly off of a modest-sized solar panel directly without the losses from an inverter or battery storage.

There should be a thermal mass wall completely shaded within the building to be cooled (I doubt you EVER really wasnt solar gain in south Florida). The wall should be as tall as you can make it, and can include the convection tubes described above.

Each component of the system works whenever the necessary energy source is available.

Whenever you cook or bake, you are also re-concentrating dessicant.

Whenever the sun is shining, you are pumping refigerant and dessicant to produce chilled water which is circulating through your heat-sink wall and cool it.

Whenever the interior temperature of the house is significantly above that of the heat-sink wall, the passive convection design will draw that heat back into the heat sink.

There is no reason that these processes have to take place at the same time, since the concentrated dessicant stores the value of the heat in chemical form.


<span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Text" property="dct:title" rel="dct:type">Concept for off-grid absorption cooling</span> by <span xmlns:cc="http://creativecommons.org/ns#" property="cc:attributionName">Albin Marcus Zuech</span> is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License.

I have been thinking about this recently for my own use, and here is what I came up with:

An absorption chiller (water/lithium bromide) DOES NOT USE HEAT TO COOL, it uses vacuum to evaporate the refrigerant (water), a dessicant (lithium bromide solution) to absorb the water vapor in order to maintain the vacuum, and heat to re-concentrate the dessicant by boiling off the water.

In commercial systems, all of this usually happens simultaneously (so that you need heat to run the system as well as power for the pumps), but there is no reason that it needs to.

If you retrofitted a small absorption chiller with a VERY LARGE dessicant storage tank and very large used dessicant tank, you could use heat whenever it was available to reconcentrate dessicant, even if your system was not cooling at that time. This heat could come from whatever stove you use for cooking/baking or other process. Because the system is primarily plumbing, you could put the cookstove, dessicant boiler, and dessicant storage tank in a seperate building with little difficulty, thermally isolating it from the building you are trying to cool. The commercial systems I have looked at feed dessicant at low pressure, so elevating the bottom of the tank a few feet above the evaporator could give you all the pressure you would need.

In order to actually run the evaporator and circulate the chilled water requires electricity. If you found appropriate DC motors, this part of the system could be run directly off of a modest-sized solar panel directly without the losses from an inverter or battery storage.

There should be a thermal mass wall completely shaded within the building to be cooled (I doubt you EVER really wasnt solar gain in south Florida). The wall should be as tall as you can make it, and can include the convection tubes described above.

Each component of the system works whenever the necessary energy source is available.

Whenever you cook or bake, you are also re-concentrating dessicant.

Whenever the sun is shining, you are pumping refigerant and dessicant to produce chilled water which is circulating through your heat-sink wall and cool it.

Whenever the interior temperature of the house is significantly above that of the heat-sink wall, the passive convection design will draw that heat back into the heat sink.

There is no reason that these processes have to take place at the same time, since the concentrated dessicant stores the value of the heat in chemical form.


<span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Text" property="dct:title" rel="dct:type">Concept for off-grid absorption cooling</span> by <span xmlns:cc="http://creativecommons.org/ns#" property="cc:attributionName">Albin Marcus Zuech</span> is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License.

Sunny Soleil wrote:My husband and I have this dream to get food forests every mile or so, that will provide for everyone's food needs in the future.

Anyone have any insight on how this might be done in the US from a legal standpoint?

I can immagine that people might have some concern building on of these on their own land if it might make them liable for the safety of foragers/squatters. It's sad, but that is just how things seem to be in this country at this time.

Sub-dividing the land and putting the "public" parcel in some sort of trust?

aman inavan wrote:I don't know the answer but it brought up another question

Could you build a hugelkultur bed over a tree stump instead of labouring to remove a stump

aman

This makes me think of a thought I have been kicking around:

It seems from what I have read that people are using long hugelkultur mounds across a slope as a kind of swale or terrace. In my vision, the mounds would be slightly off-contour to move runoff across the slope in a determined direction, with water running downslope at the far end and being "caught" by the next downhill "hugeldike", which would direct it back across the slope to the other edge of the area being developed.

The overall effect being a longer and slower zig-zagging runnoff path for water. More time to soak rainwater into the soil and there is a long exposure of running water to the hugeldikes, which absorb a maximum of water during each rain.

I realise that this is not an orrigional idea, but when I envision this, I picture doing it on a newly cleared patch of sloped forrest, having wood and stumps in place. The stumps would be incorpoirated into the hugeldikes, with the largest logs laid against the stumps on the uphill side so that the fresh stumps and their root structure would act as stakes or footings to prevent the waterlogged hugel dikes from collapsing downhill. Of course eventually both logs and stumps would lose their mechanical strength due to decay, but by then the hugel dike would have settled and become more dense and the root structure of whatever is planted on the slope would be present to stabillise the soil.

I immagine that by successively clearing and building a dike system as I descrribe and re-planting with trees, the slope could be made terraced after several generations of this treatment. New trees would be planted just downhill of each dike, becoming "stakes" for the old dike as they grew and providing the same service to the next generation of dikes.

The terraces which would result would have an extreme depth of high-organic-matter soil on their plantible faces.

Is anybody doing this?

Dave Bennett wrote:Nobody that I know of implied using this potential product instead of cob.

Wasn't saying you (or anyone else) did. I was just trying to puzzle out the responses.

Your critical method of searching widely for hidden inputs seems correct on a project basis.

I suspect that the "green concrete" skeptics on this thread are trying to get ahead of potential perverse interpretations like: "We need to quit telling people to build with cob, which is merely carbon NEUTRAL, and encourage them to build everything out of this new carbon NEGATIVE cement!!!"

Of course, the sort of simplistic thinking that would lead to that kind of attitude is unlikely to coexist in the same mind that would be receptive to your more complicated model.

Springtime Homes wrote:My main argument is something I am very familiar with: Labor Costs and Hidden Costs. The two projects I saw involved HUGE amounts of labor and took a long time to complete. Big crews of workers came every day to the job site for weeks and I doubt any of them were fueling with B100. Luckily these carbon costs were minimized by being infill projects, but this was a pretty substantial hidden carbon cost that my SIP homes do not incur. Another very difficult to calculate hidden carbon cost is the fuel that it took these workers to complete their labor (food).

I think it is important to disaggregate these factors when looking at a building system overall, and integrate them only according to the circumstances of a particular project.

I can see the requirement of a large off site labor force and it's attendant transportation use being a point of comparison of the carbon impact of differrent systems in a particular project, but not in all projects. Transporation cost is relative to the remoteness of the site. A more labor intensive building system might be more appropriate to projects sited close to an available labor force. In contrast, a building system which uses "on-site" materials in a remote undeveloped area might have a greater co2 impact if a massive bulk of soil/clay/haybales had to be trucked in to an urban building site.

If someone is selling concrete (cement?) and calling it "green", the appropriate comparison is to the standard concrete products it claims to replace. A good understanding of the impact of the concrete component itself can then be inserted into the carbon calculation of a given project.

Suppose I wanted to use this "green concrete" to pour footings for a small structure. In that case, I would probabally be able to mix the necessary quantity of concrete by hand. It would be inaccurate in that case to use co2 figures for the product which assume the use of a motorized cement mixer in figuring the overall carbon impact of the project.

The final factor named here is troubling: Food.

The workers in question were not bred for this one project, nor do they sit in stasis somewhere waiting for someone to hire them.

Would you state the converse: "Because I chose to not build with such-and-such method, 20 cement masons and their families did not eat today... Hooray for Permaculture!!!" ?