Lucky you! At one point I needed to heat my shop to get an order out and burned more than $40 worth of LPG in a single /day/.
I'll invite you to be really specific about what you mean by "commercially viable format".
The air conditioner is a two-part - or, depending on your definition of "commercially viable format", three-part problem.
Part one is to produce a Stirling cycle engine suitable for use with solar heat. We know (sorta) how to build different flavors of Stirling engines, but there's a lot of R&D needed. IMO, there's a serious lack of R and even less D - and there are significant political disincentives for correction of that problem.
My progress has been limited by the fact that I'm only able to spend about $50/month on the project. I just bought a torch, regulators, hoses, etc to that I could braze prototypes - and that outlay represented more than three months of saved-up R&D budget. Oxygen and acetylene may be do-able next month, we'll see.
My first priority isn't air-conditioning - it's a solar powered pump suitable for irrigation and village water supplies, and if you have an interest in how things are going, there's a menu of web pages at
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help keep you up to date. The last link in that menu is to a page showing progress made by some really brainy young folks who're trying to help and who don't mind getting their hands dirty to get the job done. More hands /is/ making lighter work (but their development budgets aren't any better than mine, and they also have other claims on their time and energy).
The engines that you see there are the probable forerunners of the engines that will be the core part of that air-conditioner.
It's looking more and more likely that it won't be me who gets back to you on the solar Stirling air-conditioning unit, and it may be to your kids rather than yourself, but it will happen.
It occurs to me that a MAJOR part of the success of any green heating option (and this one looks good) is INSULATION! I note a glaring lack of details on this major factor.
At the risk of stating the obvious, the issue of insulation is not tied to any particular type of heating system - green or otherwise.
If you were asking for details on the building pictured (probably not, or you'd have used a '?') I can say that I saw 6" of fiberglass in the walls, assume at least 6" of fiberglass on the ceiling, and think there's some insulation under the slab. The 10'x10' overhead door seals well all the way around but I don't know if it's insulated. I also don't know about the entry door, and I think the sliding windows are single-glazed (but I'm not sure, perhaps you can tell from the photo). If you're really interested, I have permission to provide the owners contact info, but I won't put it here.
You probably won't find many insulation details on web pages for traditional/conventional heating systems either.
[ A Google web search on "fiberglass insulation" produced 293,000 hits with the quotes, and 508,000 without. ]
governments in charge felt it was a clever way to induce some spending and offering incentives to those who want to make their homes and businesses more efficient. That includes furnaces and AC units, windows, siding, roofs etc. They widened the scope of tax incentives even to basic remodeling such as kitchens and bathrooms. (Yay for Rob)
They put a huge blower in my front door and rigged up some manometers and a computer. Lots of insulation all over the place in all the right spots.... but also all kinds of air leakage in spots I would have never guessed, and I have been around buildings a long time in many stages of con- and deconstruction. A cube of poly-urethane foam took care of most of that. IOW, you can insulate your building to the n-th degree, but if your energy bleeds to the outside, 12 FEET of insulation won't help you much.
22 electrical outlets on outside walls added up to a 6" hole by this tech's estimation. His smoke wand showed how just how much air that actually pulled. Mind you, he had a huge sucker creating a strong vacuum in my house, so 'real world' was amplified by quite a bit. Still, you see this little foam pads for electrical outlets, and I always thought they were a bit over the top, but I stand corrected. So, if you create any kind of suction, say by launching SketchUp, make sure you check for air-leaks.
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Morris, if it can get to the same level of install-ability as your heating systems, I'd consider that "commercially viable". I'd even take a lower level of maturity if it provided the cooling capability with the use of solar energy.
Not having done the research, has anybody done a study on the number of square feet of collection space required (at expected insolation levels) as a function of expected vs. required stirling efficiency?
What political disencentives exist?
Sounds like R&D outlays where I work. ;-)
Best of luck in developing the pump concept -- your heart is certainly in the right place. Slightly off topic, did you ever have any nibbles in trying to get your heating systems to Ukraine (or was it Belarus)?
Been following that web site. Looks like some reasonable proof-of-principle development has been going on, but more work to the proof-of-concept, real design is going to be a while in coming.
If it becomes profitable to do so, then development will speed up. The nice thing about the prototypes you've shown so far is that they use reasonably-priced materials. If that can carry forward, the economic viability is more likely.
For many years folks from Houston visited New Orleans where we were met with gracious and exuberant hospitality. I could tell you stories...
So, when Katrina came along, we were more than eager to repay the many instances of hospitality. We opened the Astrodome and accepted 75,000 evacuees. We tried hard to integrate them into our society.
It didn't work.
I've had more than one Houston Police officer tell me a common refrain is: "Watch you mean I can't be moseyin' in my 'hood with a malt and a toke?" Fortunately, the undesirable elements are killing each other off with great regularity and the remainder experience "Texas Justice."
We don't lack of prison space like California. During the bountiful years we built prisons as far as the eye could see. Our prison system grows virtually all its own food - except for a few things like coffee and pepper. The system has cotton fields, textile mills, and the women's unit takes the cloth and makes uniforms, bedding, and sundry items.
You might want to browse through the other stuff the Texas Department of Corrections makes. It's an interesting study.
Texas Correctional Industries
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when Hurricane Yikes! came along, and more evacuations from New Orleans seemed imminent, the Ad Hoc Vigilance Committee for New Orleans Evacuees was hastily assembled. Members jobs were to stand on the side of Interstate 10 holding signs that said "This Way to San Antonio."
The first (machine) shop that I worked in was an old aircraft hanger complete with swamp coolers. Rust was not nearly the problem I thought it would be.
The efficiency /limit/ for a Stirling cycle engine is strictly dependent on temperatures and is given by the formula
E = 1 - (Tc / Th)
where Tc is the cold head temperature in Kelvins and Th is the hot head temperature in Kelvins
Remember that temperature is NOT energy - it's the energy /density/ of some quantity of mass.
As with the solar heating panel, the trick is to nudge the design as close to that limit without pushing cost through the roof. Also like the solar heating panel, it's a matter of identifying /all/ the variables and (re)learning enough of the physics involved to make the best possible trade-off decisions. Time, heat transfer, and flow rates are important considerations in the engine and I'm pretty sure that I don't know all I need to (yet).
Under ideal conditions, the rough rule of thumb is to figure that the sun delivers roughly 1 kW of power per m^2. The amount of power (and so the area of collector) is dependent on the amount of heat to be moved.
If the collector is a passive flat panel, the temperature will be dependent on the height of the panel - and if the collector is a parabolic trough, the temperature will be dependent on the width of the trough and the width of the "bright line" to which the radiation is focused. The temperature is significant because it defines the upper limit on how efficiently the power will be converted.
Put on your favorite congress-critter's hat and consider:
Both my existing solar heating panels and the not-yet existing AC represent one-time expenditures. Once installed, there will be no fuel or electricity costs and no maintenance costs.
There will be a significant reduction in fuel and electricity revenue for those who've (probably) been among your largest campaign contributors. Ask yourself how this is likely to affect your campaign funding and your chances in the next election - will your situation be improved or worsened?
With out a need for maintenance, many jobs for those who earn a living doing annual furnace tuneups, checking and recharging AC units, and repairing breakdowns will be largely eliminated. How is this going to affect voting in the next election? Is this likely to improve or worsen the support of the trade unions who represent obsoleted workers?
And finally, answer the question of whether you want most to be re-elected or whether you care more about what your constituents pay for heating and air conditioning.
A considerable amount of web site activity - but only one nibble.
This last week, I received a video from the group in Pakistan showing their pump working. It wasn't working very well - I think because of a much too strong spring in the check valves they used - but it /is/ pumping water. I've been trying to track down some valves with weaker springs, but am having the usual difficulty with getting a US producer to even talk to me. I'm beginning to think I could make my own flapper-type check valves faster and cheaper than I could buy 'em.
Design is considerably ahead of build. The necessary rule is that only one new thing at a time can be changed, else it becomes all too easy to misinterpret test results. With the pump, the changes are still large enough to require a complete (or nearly complete) rebuild, which slows things down a lot.
I'm really looking forward to the "fine tuning" stage. :)
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