geothermal solar thermal storage

[Clive Arthur]

On 27/01/2020 01:33, Jamie M wrote:

Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."

cheers,
Jamie

I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

Cheers
--
Clive

 

[Phil Hobbs]

On 2020-01-27 17:45, Rick C wrote:

On Monday, January 27, 2020 at 3:42:53 PM UTC-5, George Herold
wrote:
On Monday, January 27, 2020 at 12:53:28 AM UTC-5,
upsid...@downunder.com wrote:
On Sun, 26 Jan 2020 17:33:08 -0800, Jamie M <jmorken@shaw.ca
wrote:

Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the
ground, and in the winter the heat is extracted from the
ground:

What so special about this ? There are a lot ground loop heat
pump installation, in which a large ground loop is installed 1-2
m below ground in the garden. While some people call this
"geothermal" but it is just seasonal storage. The ground is
heated in the summer and that heath energy is extracted in the
winter. The snow cover in the winter reduces the heat loss
directly from the ground.

If the garden is too small and too much heat is extracted from
the ground, the ground temperature may fall below 0 C, in the
spring freezing the ground and nothing will grow in the garden
during the early summer. Some house owners dump air condition
heat in the summer into the ground loop, melting the garden soil
and enabling plant growth. If a solar thermal collector is added
to the system, it can be used to heat the house earlier in the
spring and also earlier dump some heat into the ground loop,
making it possible to start the growing season earlier.

With a larger garden loop, there is not even a risk for freezing
the ground towards the spring.

"The temperature of the earth will reach 80 degrees Celsius by
the end of each summer."

That is insane. If dumped into the soil, it dry up the soil
completely. If some wells drilled into the ground water that
would be a very bad idea, since the heat would flow away and may
be illegal if ground water is used for drinking water in the
area.

,

80 C does seem crazy, I wonder if it comes close in practice? I
would like to see some analysis, but storing energy as heat looks
inefficient to me... why not PV and run heat pumps from the 50 F/
10 C ground temperature (water?) to heat in winter and cool in
summer. (You'd need batteries for the PV's.)

George H.

What is inefficient about storing heat as heat??? Rather than
convert to some other form of energy (electric, motion, elevated
mass) which will have losses, heat seems perfect. Of course, that
will have losses too, so it's a horse race as to which is better,
meaning biggest bang for the buck, maintenance, reliability, etc.

The entropy increase involved in taking something very hot and using it
to heat something only mildly hot is fairly heartbreaking. Folks have
been using solar collectors to heat pits full of rocks since the '70s at
least, but so much of the energy goes into heating the storage through a
useless temperature range that it's a mugs game.

Having said that, a bit of rock storage could warm up the outside end of
your heat pump quite usefully.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Rick C]

On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:

On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.

--

Rick C.

--+ Get 1,000 miles of free Supercharging
--+ Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Monday, January 27, 2020 at 7:24:22 PM UTC-5, Phil Hobbs wrote:

On 2020-01-27 17:45, Rick C wrote:

What is inefficient about storing heat as heat??? Rather than
convert to some other form of energy (electric, motion, elevated
mass) which will have losses, heat seems perfect. Of course, that
will have losses too, so it's a horse race as to which is better,
meaning biggest bang for the buck, maintenance, reliability, etc.

The entropy increase involved in taking something very hot and using it
to heat something only mildly hot is fairly heartbreaking.

I'm not sure what you are referring to here. You do realize this is about using the Sun to heat your home, right? Can't get much hotter than that and yet heating your bath water with it rather than some arbitrary piece of real estate is a zero entropy change.

Folks have
been using solar collectors to heat pits full of rocks since the '70s at
least, but so much of the energy goes into heating the storage through a
useless temperature range that it's a mugs game.

Eh? What is useless? You mean because the rocks start at something well below your room temperature? In a system that heats all winter with stored heat that is a one time effort. The storage system never gets below a useful temperature unless it is undersized which would be a bad idea.

Having said that, a bit of rock storage could warm up the outside end of
your heat pump quite usefully.

???

--

Rick C.

-+- Get 1,000 miles of free Supercharging
-+- Tesla referral code - https://ts.la/richard11209

 

[Jamie M]

On 2020-01-27 3:56 p.m., Rick C wrote:

On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.

I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

I was considering a crazier idea before, to use stainless steel drop
pipes instead of poly tubing, and use a solar concentrator instead of
solar collector panels, and then melt the rock under the ground, thats
about as far as I got

cheers,
Jamie

 

[Jamie M]

On 2020-01-27 6:06 p.m., Jamie M wrote:

On 2020-01-27 9:20 a.m., Rick C wrote:
On Monday, January 27, 2020 at 4:42:15 AM UTC-5, Jamie M wrote:
On 2020-01-27 12:47 a.m., Rick C wrote:
On Monday, January 27, 2020 at 12:59:06 AM UTC-5, Jamie M wrote:

Solar collectors seem overpriced, I think a rectangular tall vertical
wall would be cheaper than roof mounted commercial ones, the sun angle
would not be as good especially in summer though.

In places that use air conditioning, the solar collectors could be
dual purpose, ie designed to have cold air flow through them time, and
then cool the ground (ie a thermal battery for winter house heating and
a thermal sink for summer house cooling).

cheers,
Jamie

 

[Jamie M]

On 2020-01-27 9:20 a.m., Rick C wrote:

On Monday, January 27, 2020 at 4:42:15 AM UTC-5, Jamie M wrote:
On 2020-01-27 12:47 a.m., Rick C wrote:
On Monday, January 27, 2020 at 12:59:06 AM UTC-5, Jamie M wrote:

This is probably the solar collector (800 of them for 52 houses, about
15 panels per house) used:

https://enerworks.com/downloads/Heat-Safe-Collector.pdf

They are flat plate collectors, not the evacuated tube type.

https://en.wikipedia.org/wiki/Solar_thermal_collector#Comparisons_of_flat_plate_and_evacuated_tube_collectors
I agree it is a bit surprising the thermal mass per house, ie if the
thermal battery is a 100foot sphere for 52 houses, then that would
require a 13.4foot sphere for a single house.

I get a 26 foot sphere. Divide 100 feet by the cube root of 52 or 3.7.

Oops, that sounds correct, I forgot I was using radius.



This smaller
sphere would have to be heavily insulated to have the same efficiency as
the larger thermal mass.

There is going to be more loss for a smaller sphere no matter what. But why would you think this is a good solution for a single home? I expect this only works if you can apply an economy of scale.

What thermal loss would the 26 foot sphere have compared to a 100 foot
sphere? If it is within 2x or 3x, it is still interesting to consider
possibly, although a standard geothermal heat pump would be simpler and
cheaper.

The thermal loss would be proportionally 3.7 times larger than the 100 foot sphere assuming all losses are relative to the surface area.

A geothermal heat pump will save money, but it won't reduce the energy consumption by 90%. That's an impressive number. With the emphasis on reducing the carbon footprint it's ironic that they burn gas as the backup heat for the 10%. I'm not sure if a geothermal unit will even cut your electric use by 50%. It is supposed to pay for itself.


For a single house maybe instead of 15 panels, 30 panels would be
required to account for larger thermal battery losses in a 26 foot
sphere. That is a large up front cost, but has some advantages by not
having a heat pump, also the solar collector panels could be cheaper
(molded plastic types) in the future or integrated into roof.

I don't know how expensive the thermal collection panels are. I have always heard that solar hot water is a better financial proposition than solar PV, but that likely has been mitigated by the relatively recent reductions in cost of solar PV.

Also for a single home, having the thermal battery under the basement
of the house might increase the overall efficiency etc.

Not if you ever need to dig it up for repair!

Not likely that it would ever need to be repaired, it is the same
construction as bore hole geothermal which last 50+ years or more, also
if the thermal battery is under the basement, then the heat can be
stored at a depth so that it begins to radiate through the basement
floor in winter as well, ie lagging 6months summer to winter.

I think to get seasonal storage of energy it would require both more solar collectors and a larger size of the bore hole storage system. Double the collectors and you likely need to double the capacity of the storage, or 25% larger diameter than we figured before, 34 feet now.

I agree, but also a lower temperature of the thermal battery to improve
efficiency I think, potentially this would require a heat pump at some
point through the winter, which could bring the thermal battery
temperature below room temperature. Phil Hobbs mentioned using a heat
pump with a thermal battery. That could also be an alternative
to gas backup heat. A reversible heat pump could also be used before
winter to increase the thermal battery temperature ~10C more etc.

I just did a calculation and in winter my roof pitch is 16.6° off the angle of the sun and in summer it is 30.4° off. That is not bad.

Solar collectors seem overpriced, I think a rectangular tall vertical
wall would be cheaper than roof mounted commercial ones, the sun angle
would not be as good especially in summer though.

cheers,
Jamie

 

[Bill Sloman]

On Tuesday, January 28, 2020 at 12:38:08 PM UTC+11, Jamie M wrote:

On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That would be ice-nine, or something like it - which is to say, science fiction.

https://en.wikipedia.org/wiki/Cat%27s_Cradle

<snipped the rest>

--
Bill Sloman, Sydney

 

[Jamie M]

On 2020-01-27 6:58 p.m., Rick C wrote:

On Monday, January 27, 2020 at 8:38:08 PM UTC-5, Jamie M wrote:
On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

That would be a chemical reaction and I've not see any that weren't primary batteries, i.e. non-rechargeable. Otherwise the storage is either based on using specific heat to store energy at increasing temperatures or phase change to store heat at a given temperature that is higher than the temperature required.

The system discussed above uses specific heat of the earth to store energy.

wiki page and a 10 year report:

https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

https://www.dlsc.ca/reports/swc2017-0033-Mesquita.pdf

I was considering a crazier idea before, to use stainless steel drop
pipes instead of poly tubing, and use a solar concentrator instead of
solar collector panels, and then melt the rock under the ground, thats
about as far as I got

Melt rock??? Yeah, that's gonna take a lot of mirrors. I believe there's a few you can get cheap at Crescent Dunes.

 

[Rick C]

On Monday, January 27, 2020 at 8:38:08 PM UTC-5, Jamie M wrote:

On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

That would be a chemical reaction and I've not see any that weren't primary batteries, i.e. non-rechargeable. Otherwise the storage is either based on using specific heat to store energy at increasing temperatures or phase change to store heat at a given temperature that is higher than the temperature required.

The system discussed above uses specific heat of the earth to store energy.

I was considering a crazier idea before, to use stainless steel drop
pipes instead of poly tubing, and use a solar concentrator instead of
solar collector panels, and then melt the rock under the ground, thats
about as far as I got

Melt rock??? Yeah, that's gonna take a lot of mirrors. I believe there's a few you can get cheap at Crescent Dunes.

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[Jasen Betts]

On 2020-01-28, Jamie M <jmorken@shaw.ca> wrote:

On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

Eg hydrated copper sulphate (blue crystals) can be converted to anhydrous
copper sulphate (white crystals) by heating it (which produces water
vapour). the crystals can be stored cold if kept dry. reintroduction
of water gives a release of heat. (11.3kJ/mol) - it's not very
efficient: less than 6% just accounting for boiling the water.

There are probably better reactions than this, it's just one I
remeber from high school.

That could be activated in portions to get rid of most of the insulation
problem etc.

I was considering a crazier idea before, to use stainless steel drop
pipes instead of poly tubing, and use a solar concentrator instead of
solar collector panels, and then melt the rock under the ground, thats
about as far as I got

just use a longer drill, you'll find molten rock eventually

--
Jasen.

 

[Clive Arthur]

On 27/01/2020 23:56, Rick C wrote:

On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.

I'm thinking or the supersaturated solution packs you get for camping or
in my case, cold funerals. They're sealed packs of solution, heating
them dissolves the solid in the liquid. Then they are allowed to cool
and you can store them for ever without insulation in this 'charged'
state. When you 'hit them' - a physical shock from flexing a metal disk
- the solid crystallises out giving heat. They are, or were, quite common.

Of course, you'd use a heat exchanger as 'charged' packets cooled to
pre-heat 'discharged' packets. And I'm not literally suggesting
thousands of individual packets, though you would need some way of
stopping the phase change from spreading more than required.

While Googling for you, I came across this...

https://www.bbc.co.uk/news/uk-scotland-40188414

....damn, too late again!

--
Cheers
Clive

 

[Rick C]

On Tuesday, January 28, 2020 at 4:14:39 AM UTC-5, Clive Arthur wrote:

On 27/01/2020 23:56, Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I'm thinking or the supersaturated solution packs you get for camping or
in my case, cold funerals. They're sealed packs of solution, heating
them dissolves the solid in the liquid. Then they are allowed to cool
and you can store them for ever without insulation in this 'charged'
state. When you 'hit them' - a physical shock from flexing a metal disk
- the solid crystallises out giving heat. They are, or were, quite common.

Of course, you'd use a heat exchanger as 'charged' packets cooled to
pre-heat 'discharged' packets. And I'm not literally suggesting
thousands of individual packets, though you would need some way of
stopping the phase change from spreading more than required.

While Googling for you, I came across this...

https://www.bbc.co.uk/news/uk-scotland-40188414

...damn, too late again!

Not sure why you say googling for me. I've never seen these hand warmers and wouldn't know what to look for. It's great that they figured this out. I'm wondering if they are truly practical or not. There's a lot of details that need to be right to get the efficiency right, etc. At one point they talk about twice the temperature of boiling water! But this isn't a scientific article so you have to take that sort of stuff with a grain of salt.

I noticed somethings about the Drake Landing project. The efficiency of the underground storage is only around 50% if I am reading the data correctly.. So only 50% of the energy pumped into the ground ever comes back out.

I expect the efficiency of the phase change of the crystals would be better.... but there are other issues that affect the efficiency. The process of heating the solid to form the gel will have losses depending on how hot it needs to be. The solid is heated to form the gel, then if the storage is very long the specific heat energy will be lost from cooling. How much that is depends on the temperature required to form the gel. But 50% isn't a difficult target to meet I expect.

The intended application for this is diurnal storage which it would seem to be a good match for.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[George Herold]

On Monday, January 27, 2020 at 7:24:22 PM UTC-5, Phil Hobbs wrote:

On 2020-01-27 17:45, Rick C wrote:
On Monday, January 27, 2020 at 3:42:53 PM UTC-5, George Herold
wrote:
On Monday, January 27, 2020 at 12:53:28 AM UTC-5,
upsid...@downunder.com wrote:
On Sun, 26 Jan 2020 17:33:08 -0800, Jamie M <jmorken@shaw.ca
wrote:

Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the
ground, and in the winter the heat is extracted from the
ground:

What so special about this ? There are a lot ground loop heat
pump installation, in which a large ground loop is installed 1-2
m below ground in the garden. While some people call this
"geothermal" but it is just seasonal storage. The ground is
heated in the summer and that heath energy is extracted in the
winter. The snow cover in the winter reduces the heat loss
directly from the ground.

If the garden is too small and too much heat is extracted from
the ground, the ground temperature may fall below 0 C, in the
spring freezing the ground and nothing will grow in the garden
during the early summer. Some house owners dump air condition
heat in the summer into the ground loop, melting the garden soil
and enabling plant growth. If a solar thermal collector is added
to the system, it can be used to heat the house earlier in the
spring and also earlier dump some heat into the ground loop,
making it possible to start the growing season earlier.

With a larger garden loop, there is not even a risk for freezing
the ground towards the spring.

"The temperature of the earth will reach 80 degrees Celsius by
the end of each summer."

That is insane. If dumped into the soil, it dry up the soil
completely. If some wells drilled into the ground water that
would be a very bad idea, since the heat would flow away and may
be illegal if ground water is used for drinking water in the
area.

,

80 C does seem crazy, I wonder if it comes close in practice? I
would like to see some analysis, but storing energy as heat looks
inefficient to me... why not PV and run heat pumps from the 50 F/
10 C ground temperature (water?) to heat in winter and cool in
summer. (You'd need batteries for the PV's.)

George H.

What is inefficient about storing heat as heat??? Rather than
convert to some other form of energy (electric, motion, elevated
mass) which will have losses, heat seems perfect. Of course, that
will have losses too, so it's a horse race as to which is better,
meaning biggest bang for the buck, maintenance, reliability, etc.

The entropy increase involved in taking something very hot and using it
to heat something only mildly hot is fairly heartbreaking. Folks have
been using solar collectors to heat pits full of rocks since the '70s at
least, but so much of the energy goes into heating the storage through a
useless temperature range that it's a mugs game.

Yeah, heat is the least useful form of energy. I don't know what the
numbers look like, but for all the trouble of heat capture.. I wonder
if solar PV would make more sense.

Having said that, a bit of rock storage could warm up the outside end of
your heat pump quite usefully.

Yup, If we'd had force air heating in my house I would have looked into
a heat pump with some ground water (or dirt) to source and sink the
heat from. (When the last oil furnace crapped out.)

George H.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[whit3rd]

On Monday, January 27, 2020 at 9:32:03 AM UTC-8, Rick C wrote:

On Monday, January 27, 2020 at 7:12:06 AM UTC-5, Bill Sloman wrote:

If I remember rightly, the temperature 45cm below the surface lags the seasons by six months (or 180 degrees) which is exactly what you want.

Not really. It is an irrelevant statistic. The issue at hand is heat loss.

No, because the heat was free; the issue is the amount of excavation to
install the heat exchangers. The heat exchanger gets you the heat until
the end of winter, at which point the mass can be at ambient temperature (zero loss
regardless of insulation), so initial heat loss can be high and it'll still work out.

> And a better insulator.

In economic terms, a layer of clay to inhibit water movement might be more important than
insulation. The dirt-layer thickness multiplies the R-value at no great cost; heck, the core of this
planet is hot enough to melt iron, but our feet aren't burning.

 

On Tuesday, 28 January 2020 03:44:31 UTC, Jamie M wrote:

On 2020-01-27 6:58 p.m., Rick C wrote:
On Monday, January 27, 2020 at 8:38:08 PM UTC-5, Jamie M wrote:
On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

That would be a chemical reaction and I've not see any that weren't primary batteries, i.e. non-rechargeable. Otherwise the storage is either based on using specific heat to store energy at increasing temperatures or phase change to store heat at a given temperature that is higher than the temperature required.

The system discussed above uses specific heat of the earth to store energy.


wiki page and a 10 year report:

https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

claims
"In 2012 the installation achieved a world record solar fraction of 97%; that is, providing that amount of the community's heating requirements with solar energy over a one-year time span.[5][6]"

even though there are several other places running on 100% solar heat

 

[Rick C]

On Tuesday, January 28, 2020 at 2:10:41 PM UTC-5, whit3rd wrote:

On Monday, January 27, 2020 at 9:32:03 AM UTC-8, Rick C wrote:
On Monday, January 27, 2020 at 7:12:06 AM UTC-5, Bill Sloman wrote:

If I remember rightly, the temperature 45cm below the surface lags the seasons by six months (or 180 degrees) which is exactly what you want.

Not really. It is an irrelevant statistic. The issue at hand is heat loss.

No, because the heat was free;

The heat is very much not free. To capture the heat requires the collectors which cost money, real money. In fact, as much as that they use roof space which is also limited. Notice the garage roofs with the collectors are very tall to provide the right angle for the collectors. They have maxed out the garages and would have needed to add more to the homes with the same odd looking roof line.

the issue is the amount of excavation to
install the heat exchangers. The heat exchanger gets you the heat until
the end of winter, at which point the mass can be at ambient temperature (zero loss
regardless of insulation), so initial heat loss can be high and it'll still work out.

Only if you have enough heat going into the reservoir to compensate for the heat loss in storage. The data they provide seems to show a 50% efficiency of the ground reservoir. If it were better they could have saved money on the collectors or provided more heat to the homes requiring less gas to be burned.

And a better insulator.

In economic terms, a layer of clay to inhibit water movement might be more important than
insulation. The dirt-layer thickness multiplies the R-value at no great cost; heck, the core of this
planet is hot enough to melt iron, but our feet aren't burning.

There's some difference between the miles of earth between us and the mantle and few feet of soil around the bore hole thermal storage. The plan is to heat the soil around the pipes reversibly. The lack of good insulation results in much less reversible heating of a large amount of soil around the reservoir, lost heat. I'm not sure how much good insulation around the core would do really. When you are talking about months of storage, I'm not sure increasing the insulation by R-12 will really accomplish much. The ground "insulates" by establishing a thermal gradient once the surrounding soil is also heated. That's where the other 50% of the heat goes.

It was interesting to see that they learned a lot about managing the coolant flow to save on electricity costs of running the pumps. I believe they reduced it by a factor of 2 over the course of 10 years. There's a lot of interesting data there.

--

Rick C.

+-+ Get 1,000 miles of free Supercharging
+-+ Tesla referral code - https://ts.la/richard11209

 

[Jamie M]

On 2020-01-28 4:40 p.m., tabbypurr@gmail.com wrote:

On Tuesday, 28 January 2020 03:44:31 UTC, Jamie M wrote:
On 2020-01-27 6:58 p.m., Rick C wrote:
On Monday, January 27, 2020 at 8:38:08 PM UTC-5, Jamie M wrote:
On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

That would be a chemical reaction and I've not see any that weren't primary batteries, i.e. non-rechargeable. Otherwise the storage is either based on using specific heat to store energy at increasing temperatures or phase change to store heat at a given temperature that is higher than the temperature required.

The system discussed above uses specific heat of the earth to store energy.


wiki page and a 10 year report:

https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

claims
"In 2012 the installation achieved a world record solar fraction of 97%; that is, providing that amount of the community's heating requirements with solar energy over a one-year time span.[5][6]"

even though there are several other places running on 100% solar heat

Hi,

The 97% is from 2011-2012, in 2015-2016 they had a solar fraction of 1.
(page 5 of the pdf).

It is a bit silly to design the system capacity so close to the usage,
ideally it would have capacity always a bit greater than usage.

cheers,
Jamie

 

[Rick C]

On Wednesday, January 29, 2020 at 12:00:26 AM UTC-5, Jamie M wrote:

On 2020-01-28 4:40 p.m., tabbypurr@gmail.com wrote:
On Tuesday, 28 January 2020 03:44:31 UTC, Jamie M wrote:
On 2020-01-27 6:58 p.m., Rick C wrote:
On Monday, January 27, 2020 at 8:38:08 PM UTC-5, Jamie M wrote:
On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

That would be a chemical reaction and I've not see any that weren't primary batteries, i.e. non-rechargeable. Otherwise the storage is either based on using specific heat to store energy at increasing temperatures or phase change to store heat at a given temperature that is higher than the temperature required.

The system discussed above uses specific heat of the earth to store energy.


wiki page and a 10 year report:

https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

claims
"In 2012 the installation achieved a world record solar fraction of 97%; that is, providing that amount of the community's heating requirements with solar energy over a one-year time span.[5][6]"

even though there are several other places running on 100% solar heat


Hi,

The 97% is from 2011-2012, in 2015-2016 they had a solar fraction of 1.
(page 5 of the pdf).

It is a bit silly to design the system capacity so close to the usage,
ideally it would have capacity always a bit greater than usage.

And how would you come up with that number??? It is very hard to design something that will always do the job. It might cost a lot more as well. You won't even be able to save on installing the gas backup since you will still need that for breakdowns. Then there is the issue of the gas company not being happy with a customer how uses gas once in 10 years.

It seems very practical to use some other heat source for 10% of your heating needs routinely and saving a lot of money on overdesign. I wish they had used electric as backup. Eventually that will be carbon free which is where we need to be.

--

Rick C.

++- Get 1,000 miles of free Supercharging
++- Tesla referral code - https://ts.la/richard11209

 

[Jamie M]

On 2020-01-28 9:59 p.m., Rick C wrote:

On Wednesday, January 29, 2020 at 12:00:26 AM UTC-5, Jamie M wrote:
On 2020-01-28 4:40 p.m., tabbypurr@gmail.com wrote:
On Tuesday, 28 January 2020 03:44:31 UTC, Jamie M wrote:
On 2020-01-27 6:58 p.m., Rick C wrote:
On Monday, January 27, 2020 at 8:38:08 PM UTC-5, Jamie M wrote:
On 2020-01-27 3:56 p.m., Rick C wrote:
On Monday, January 27, 2020 at 6:27:01 PM UTC-5, Clive Arthur wrote:
On 27/01/2020 01:33, Jamie M wrote:
Hi,

Here is an interesting geothermal project:

http://www.dlsc.ca/how.htm

In the summer solar thermal collectors are used to heat the ground, and
in the winter the heat is extracted from the ground:

"The temperature of the earth will reach 80 degrees Celsius by the end
of each summer."


I wonder if a phase-change substance could be used, like in hand
warmers. No need to insulate, just hit it when you need the heat.

"Hit it"??? What does that mean??? Even phase change material will be at an elevated temperature and require insulation. It may not need to be 80°C, but if the phase change is at a lower temperature than ambient it won't do you much good for heating.


I think he is referring to an active thermal battery, ie a material that
stores energy molecularly, which can be triggered to store or release
the energy thermally, maybe with an electric field etc.

That could be activated in portions to get rid of most of the insulation
problem etc.

That would be a chemical reaction and I've not see any that weren't primary batteries, i.e. non-rechargeable. Otherwise the storage is either based on using specific heat to store energy at increasing temperatures or phase change to store heat at a given temperature that is higher than the temperature required.

The system discussed above uses specific heat of the earth to store energy.


wiki page and a 10 year report:

https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

claims
"In 2012 the installation achieved a world record solar fraction of 97%; that is, providing that amount of the community's heating requirements with solar energy over a one-year time span.[5][6]"

even though there are several other places running on 100% solar heat


Hi,

The 97% is from 2011-2012, in 2015-2016 they had a solar fraction of 1.
(page 5 of the pdf).

It is a bit silly to design the system capacity so close to the usage,
ideally it would have capacity always a bit greater than usage.

And how would you come up with that number??? It is very hard to design something that will always do the job. It might cost a lot more as well. You won't even be able to save on installing the gas backup since you will still need that for breakdowns. Then there is the issue of the gas company not being happy with a customer how uses gas once in 10 years.

It seems very practical to use some other heat source for 10% of your heating needs routinely and saving a lot of money on overdesign. I wish they had used electric as backup. Eventually that will be carbon free which is where we need to be.

Yes gas backup is really strange since it has such a low overall
utilization, but I guess people would use it for more than heating.

cheers,
Jamie