geothermal solar thermal storage

[Rick C]

On Wednesday, January 29, 2020 at 3:26:58 AM UTC-5, Jamie M wrote:

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.

The only other thing I can think of is cooking. That doesn't really use so much energy.

This is an interesting project. They are paying an average of $60 a month I believe they said. That is less than I pay when my winter heating bill is averaged and what I expect am paying for hot water. But the cost savings is not all that much I don't think. They still need A/C which this system doesn't provide, so once you factor that cost into the equation I expect the cost difference is fairly small... if they are even considering the cost of installation which seems to have been paid for by grants.

--

Rick C.

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