home geothermal
dragmit
used for underground gasoline storage. I intend to bury this tank 30
feet below ground, fill it with rail road ballast, then circulate a
brine solution, (like the stuff used in midwest solar collectors)
through solar collectors during the late spring, summer and early
fall. My intention is to get the brine up to a few hundred degrees so
that I can lator circulate this brine through a heat exchanger, then
through a standard hot water home heat system. My mission is to
remove my residence from the natural gas grid. I will be using
plastic pipe for all brine transfer except for the heat exchangers,
which I have to research more. I will probably spring for stainless
steel.
Does anyone here have any data on the difference between solar
reflector light concentration vs a simple magnifying glass? I had
originally thought a grid of magnifying glasses focused along a length
of blackened stainless pipe would do the trick, but I have seen
commercial solar concentrators used in the midwest that seem
impressive. However cost is an issue obviously. I intend to use
computer tracking for direct sunlight, as well as to transfer fluid
when temps are right. Any input?
DanB
> I picked up a 10,000 gallon fiberglass tank last week like the ones
> used for underground gasoline storage. I intend to bury this tank 30
> feet below ground, fill it with rail road ballast, then circulate a
> brine solution, (like the stuff used in midwest solar collectors)
> through solar collectors during the late spring, summer and early
> fall. My intention is to get the brine up to a few hundred degrees so
> that I can lator circulate this brine through a heat exchanger, then
> through a standard hot water home heat system. My mission is to
> remove my residence from the natural gas grid. I will be using
> plastic pipe for all brine transfer except for the heat exchangers,
> which I have to research more. I will probably spring for stainless
> steel.
Most stone has a specific heat a fraction of water.
<http://www.engineeringtoolbox.com/specific-heat-solids-d_154.html>
So some 600f of 'solid' rock would yeild the same storage of 200f water
if you took them both to 100f at the lower end. As you are not looking
to drive a heat engine, I don't see the point.
100f of differential with water is ~8^6 btu, or the equivalent of 80
gallons of fuel oil. I don't know about where you live but in the
mountains of AZ I can burn through 30-50^6 btu of fuel in a winter.
Why 30 feet? Where did you get that number?
> Does anyone here have any data on the difference between solar
> reflector light concentration vs a simple magnifying glass? I had
> originally thought a grid of magnifying glasses focused along a length
> of blackened stainless pipe would do the trick, but I have seen
> commercial solar concentrators used in the midwest that seem
> impressive. However cost is an issue obviously. I intend to use
> computer tracking for direct sunlight, as well as to transfer fluid
> when temps are right. Any input?
You can't possibly be thinking 'magnifying glass' as in classical, do
you mean Fresnel lenses? There have been prototypes for trough Fresnel
collectors, But I don't know of any commercially viable.
Reflectors are most common, 'cost'. You need to crunch some numbers. If
this were easy, everyone would be doing it...
dragmit
I am looking to access as stable a temperature environment as
possible. Common earth is one of the best insulators on the planet.
I am looking at 30 feet below grade because the temperature at this
level should stay fairly the same year round. Once an enclosure at
this level enclosed by earth is heated, its temp should hold relativly
well once the temp is brought up to 200 to 300 degrees. The issue
with rock is, if I heat one cubic foot of rock to 200 degrees
Farenheit, it will still be very close to 200 degrees ten seconds
lator, as a 200 degree cubic foot of air would have cooled in the same
environment. Does it not take many less joules to heat a cubic foot
of air up to 200 degrees than a cubic foot of rock? If so, does that
not mean there is more heat energy in a cubic foot of rock at 200
degrees than a cubic foot of air at the same temp? The ft cubed rock
will store much more energy than the same amount of water.
A 10,000 gallon tank of rock and fluid heated to 250 degrees should
provide a fair amount of heat for a while. The whole heating season
remains to be seen, but if I can bring natural gas use to zero by
installing another one of these things, or even a third, would it not
be worth the price? This thing would last as long as the house, with
few repairs or energy purchase input, so payback would be a small
fraction of the houses life. About $1200 a year for me. If this
install runs ovet $5000 I would be suprised, but economically in these
results $20,000 would be acceptable.
Yes, you have addressed one of my questions. I took a common
magnifying glass as a kid and started a piece of paper on fire with it
using a 3 inch common mag glass. Is a 'Fresnel lense' better at
concentrating sunlight? Would a reflector as an option require more
stringent alignment with the sun or less?
>You need to crunch some numbers.
Crunching numbers is my favorite part.
> If this were easy, everyone would be doing it...
If everyone was, why would I need to?
I watched and listened to my fellow students whine and complain
about how hard the Calculus class was. I couldn't imagine what their
problem was ... But their poor math skills didn't keep them from
getting their degree.
On Dec 27, 11:36 am, DanB <a...@some.net> wrote:
> dragmit wrote:
> > I picked up a 10,000 gallon fiberglass tank last week like the ones
...