Drawing and Feasibility Question 3

[Pivotal]

First off I am brand new to these forums, (first post) but am looking for a forum where i can get an idea out there and learn on how to make it better. Ultimately before going out and spending who knows how much money on a prototype, run up against some engineers who can either shoot it down or show where the weakness in system are. Hopefully get some positive feedback on how to improve it somewhat.

this is more or less a hair brained idea, I drew up. It is not to scale and still in a very rough state, just enough to point to something while getting the idea across.

Now the questions are:
1. Would it actually work?
2. What would stop it from working?
3. How can it be modified to make it more efficient?

So the basic idea is:

1. create a passive solar system to Heat water(thermo-siphon)
2. use the themo-siphon to run water and air thru earth pipes (as a heat exchanger)
3. push cold water and air into an insulted box to use as an air-conditioner.
4. drop the cooled water back into the thermo-siphon to be heated again
5. use the hot point from the thermo-siphon, and the cold point from the cooler to run a sterling engine.

Image to show concept:

 

[CastMetal]

Here is a good source of info for sterling engines. Also cites many more resources.

http://www.inference.phy.cam.ac.uk/sustainable/refs/solar/Stirling.pdf

1. It will work, it has been done before.
2. Lack of sufficient temperature differential in hot and cold
3. The engine may get upwards of 20% efficiency

Comprehension is not understanding. Understanding is not wisdom. And it is wisdom that gives us the ability to apply what we know, to our real world situations

 

[dvd]

That's a mighty fancy image with a copyright at the bottom.

Did you create that just to start this discussion?

If not, where is the illustration from so that everyone is on the same page?

 

[Pivotal]

Thanks CastMetal, the sterling was just an idea as a way to use the temp delta, I'm thinking it should be enough to drive a fan or blower minimum or possibly even a pump. It is a side process, the main energy savers should be coming from the water heater, solar furnace, and earth pipe air conditioner.

The paper is definitely an eye opener, interesting on how far back they have been trying to couple a sterling to solar power. It is a nice and compact paper too on where to find past research, thank you it is going to invaluable to me as I keep exploring and researching this idea.

Perhaps a little background into why I am looking at this would also be helpful. I am currently looking at land in the California desert (retirement). It is a large enough piece of land to set up solar collectors and allow for the comfortable use of earth pipes. Generating heat to store into a thermal mass should not be a problem. Removing heat from the living space in the summer time is my main area of concern. This is also a DIY project as I am not exactly rich, otherwise I'd be looking at Hawaii So before starting i want to get it right, so there are minimal correction along the way, trying to avoid the "oh that should have worked" moments.

The system is more for cooling the house down, where electric bills would be insane, unless a means of passively accomplishing this is found. This would also be a build from the ground up so no need to rework existing structures. Wind scoops for ventilation would also be taken into consideration. The main piece to success I believe is going to be the availability of water.

Do you have an example of this working in an actual building, whether residential or industrial. Would love to see how it was done, or a case study showing the pros and cons of various approaches.

-------------

dvd, yes I drew this up, to start the discussion it is an idea I have been mulling over for a while now. There have been many napkin drawings prior to this to get it to this point.

As for the copyright, you are all free to use it anyway you see fit, as long as you do not remove the copyright

 

[IRstuff]

As a general rule, conversion to heat should be the last thing to be done, since heat conversion to mechanical or electrical is relatively inefficient.

Given that the target environment is the desert, one might argue that solar electrical would be a better choice, since you could, at a minimum, sell to the utility. A [link

http://www.costco.com/Browse/Produc...15&Ntx=mode+matchallpartial&Nty=1&topnav=&s=1

]5kW system[/url] from Costco runs $18K, with the smallest system, [link

http://www.costco.com/Browse/Produc...12&Ntx=mode+matchallpartial&Nty=1&topnav=&s=1

]880 watt[/url], running $3.6K. Supposedly, it will supply about 72% of an average home's electricity, consuming about 36 m^2 of area.

Major advantages:
> electrical power is considered to be "high" quality, since conversion to mechanical or thermal is easier and efficient
> no moving parts and no fluids, so no mechanical maintenance required, and no risk of leaks from corrosion from the fluid
> potential to sell power to utility, which cannot be done with thermal power at all.
> elimination of inaccessible plumbing running under the house
> ease of upgrade in the future; more efficient panels or panel replacement is relatively plug&play, compared to something with plumbing.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[dvd]

I agree with IRstuff. The proposed system looks to have a lot of money tied up in materials and labor. Better to place photvoltaics in a convenient location. If you move/sell, a custom-built system will not be too attractive to the next owner.

 

[Pivotal]

Thanx IRstuf for the response:

Just reconfiguring how the water would flow and adding additional material and labor to the plumbing side of the equation. Thinking of using the water flow to extract energy from the environment. Another aspect to this would be to lower the photovoltaics footprint, and possibly "if" there is enough of a differential in temperature to drive a sterling engine.

Just thinking the less I need to recharge the batteries the longer they would last. Also trying to lower the amount of batteries actually needed to store electricity. pound for pound with the price of natural gas out here it could technically be run on natural gas from an expenses perspective to keep the bills fairly low.

At 46 cents per term current price
$5.75 per Million BTU of Heat delivered to home
$546.25 per year for normal home for Natural Gas
source:

http://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/

However, my curiosity has gotten the best of me, and would like to try and do this so it is as self sustaining and passive as possible.

Not as worried about it being super efficient as I am about having the system balanced. There are some high temperature differences between summer and winter. Avgerage 96F in July to 30F in January (so potential freezing) ... Also day vs night temps can vary 20-30 degrees F (this may be beneficial in recharging the system though)


Regardless of how it is built the plumbing and electrical systems would still need to be installed. The excavation and grading of the property still needs to occur. So some of the costs are being shared, this is something to keep in mind. The inverter and battery systems are a given whether it is PV, solar thermal, or burning fuel to generate electricity. If it was an existing structure, then PV panels all the way I agree retrofitting an existing structure would be very costly. But building it from the groud up should only add small increases to the final cost of the building. i may be wrong in thinking this and have been shockingly wrong at considerable expense to myself in the past, which is why I'm researching this as thoroughly as possible. Talk and discussion is cheap, design mistakes when building are costly.

currently looking at ideas like the following:

http://www.solarhaven.org/SolarHavenMainPage.htm

http://www.zeroenergy.com/

http://calearth.org/

http://www.cobprojects.info/

Ground Coupled Heat Pumps Discussion

http://www.1supply.com/info/products/heatpump.pdf

 

[IRstuff]

A tiny story. We designed a product under IR&D, and got the Navy to buy 26 units at about $1M apiece. Only problem was that the Navy neglected to fund the maintenance costs, which ran about $50M for 20 years.

Your initial cost is often not the issue at all. The issue will be the maintenance and repair, particularly for an electromechanical system that is moving fluids around. When, not if, the system develops leaks in the foundation, or under the house, that's when the costs really begin to be incurred. Digging up a foundation or digging under an existing structure will not be cheap.

Every project needs to analyzed for Total Ownership Cost, and in many cases, that cost is several times the initial cost of procurement and fabrication.

As for "extracting" heat, unless you have a geothermal pipe under your house, the ROI is generally negative for such systems. Even in industrial circles, it's understood that waste heat recovery noly makes sense if you have gobs of it, because the efficiency is really poor for converting a few degrees of temperature delta into meaningful amounts of energy.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[flash3780]

Why not capture the solar radiation with a big parabolic dish? Also, why the big greenhouse? Couldn't you just run your heat exchanger tubes through glass pipe under a vacuum? Again, it'd probably be cheaper than building that big structure.

Also, you might be surprised how much area you need to capture enough solar energy to generate an appreciable amount of power (especially in the winter).

Regardless, it looks like a fun experiment. I work with Stirling engines; they're pretty cool little devices.

 

[Pivotal]

IRstuff thanx for the reality check What are your thoughts on doing this as a geothermal bore hole instead.

1. I do not know what the permits would be like in this area, strong EPA regulations.

2. If the property already has a well, or if a well needs to be dug then the expense would still need to occur.

-- Side Note: Perhaps I would need to look towards the Arizona desert in areas where water is slightly easier to acquire.

then there would be an extraction or dumping of heat into a ground water source. (probably really hard to get permits for, unless someone already has experience with this) As for property with water rights I have made a quick survey and it would run roughly at about $5K-9k per acre on the cheap side. Properties looked at already had wells on them. It is a little more expensive but may be worth it for the additional resource.

Photo-voltaic would also need to be replaced, batteries go dead, along with any inverters and central air units, all run a risk of maintenance costs. but definitely cheaper then having to re-excavate. It definitely would not have been under the structure, because then I might as well just invest in a bulldozer

Also have a real life example of a commercial scale PV system where I work. This was installed about 2 years ago. Basically the electric bill averages 35k per month the electricity is sold back to the grid for a credit of $3500 per month, and it's a 1.5 mil dollar install. So a 10% return on the electric bill. The PVs need to be cleaned twice a year with distilled water (to avoid hard water scaling) by someone who knows what they are doing. Their efficiency also drops dramatically when dusty. There is a lot of dust in desert environments, also the surface gets scratched. Life of the system is guaranteed for 20 years.

----------------------------

flash3780 the greenhouse would help capture heat before it got to the main living space, theoretically it should help keep the living space temperature more stabilized. Sort of acts as an extra layer of insulation.

The Calif/Arizona desert gets 300+ days of sunshine that is the one thing there is plenty of, what it is lacking is water to be able to use it at it's full potential. There is a lot of heat being naturally created, question is can it be tapped and put to good use at a residential level in a DIY project. Basically i could create all the hotwater I would ever need, possibly even steam with the right equipment. Parabolic mirrors and Fresnel lens come to mind. However the pressure vessels (cost) and safety concerns ($$$) around this type of system would need to be addressed.

The space requirement for this type of system is being looked at. Hot water can be created in a small enough space cooling it back down enough to create the delta is where the problem lies. Preferably I would like to do this passively. If the water can be cooled sufficiently then running it through a radiator (heatsink) in the chill box would create an air-conditioner. gravity would return it to the Thermo-Siphon.

The radiator chill point vs the top of the Thermo-Siphon heat-point would create the temp delta to run the sterling. In theory at least. ultimately is how can the design tap into as much of the free heat being provided by the environment at a residential scale and still make it worth while.

IRstuff did bring up a really good point regarding maintenance costs so the full life-cycle of the system would need to be considered too.

 

[IRstuff]

Unless you know you got it, or you got bubbling holes and steam coming out the ground, geothermal isn't going to happen.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize