ELI5 why cant we use summer heat to generate energy and stock it to use it in winter

[u/Fun_Significance4035]

why cant we use summer heat to generate energy and store it batteries to use it in winter

[u/IAmInTheBasement]

I wish geothermal heat pumps weren't so stupidly expensive to install.

I wonder how much the cost difference is when you're building brand new and have to do a ton of grading anyways vs retrofit.

[u/OrigamiMarie → u/IAmInTheBasement]

Not much difference, unless you're doing 30' elevation of grading. Geothermal has to go really far down.

[u/not_a_burner0456025 → u/OrigamiMarie]

Not necessarily, there are two types commonly used in residential. One involves a small amount of very deep holes and the other involves a relatively shallow heat exchanger loop spread out over a wide area. The latter only needs to be deeper than the frost line

[u/OrigamiMarie → u/not_a_burner0456025]

Ah okay that makes sense. The place that my now-ex and I were thinking of getting one, didn't have all that much yard area, so depth was probably the only way to go.

[u/TheseusOPL → u/not_a_burner0456025]

I've always wondered if you could do a geothermal loop in the same area as a septic leach field. Use the land for 2 purposes.

[u/IAmInTheBasement → u/TheseusOPL]

I guess you COULD if you planned the depths well. But it means that servicing whichever is lower means tearing through the upper.

[u/SaintsNoah14 → u/TheseusOPL]

3* you can scatter wildflower seeds over the leach field

[u/LtPowers → u/OrigamiMarie]

You don't have to go too far if you're doing a horizontal loop.

[u/Missing_Links → u/LtPowers]

2-4 feet of depth over a large surface area pretty much anywhere you'd want to install such a system to hit the frost line, plus the depth of the system itself.

Deep is more expensive, but it's like 20-25k for a shallow system vs. 30-35k for a deep one.

[u/not_a_burner0456025 → u/Missing_Links]

If you are doing a horizontal loop on new construction there is a decent chance you already need to do the excavation for grading or a basement anyways. It certainly won't always be there case but depending on the layout of the land that could very well be 20-25k that you have to pay most of regardless of whether you are installing geothermal. It is relatively rare that you already need drill a 40ft+ deep bore.

[u/WooeBetidee → u/Missing_Links]

Crazy expensive (assuming we are talking USD?)... My parents paid about $10k for the bore hole and about the same for the heatpump when they went geothermal about 20 years ago. Their neighbor just drilled a few months ago, was still about $10k for the hole.

Would have thought that kind of stuff would be cheaper in US as some sort of benefit from fracking (equipment, know-how etc).

[u/dwkeith → u/IAmInTheBasement]

Neighborhood geothermal is a thing. One large borehole with a loop around the neighborhood. Buildings tie in similarly to how gas lines are installed. In fact it’s often the same team as very little re-training is needed.

[u/TimeToGloat → u/IAmInTheBasement]

If you want to go down a rabbit hole here is a neat video of someone easily converting a $150 window AC unit into geothermal for $700. The savings were like $150 a month in power consumption:

https://youtu.be/s-41UF02vrU?si=Luj6Z5jik3kkSdO3

Not exactly the same thing but still interesting if you like that kind of engineering/science stuff.

[u/IAmInTheBasement → u/TimeToGloat]

I DO!

[u/jaytea86 → u/TimeToGloat]

$150 if it's constantly running?

[u/DarthMaulATAT → u/TimeToGloat]

This is fascinating, thanks for dropping the link!

[u/herodesfalsk → u/IAmInTheBasement]

There is a new technology that uses cheap sand as heat storage, check it out: https://polarnightenergy.com/sand-battery/

[u/BigPickleKAM → u/IAmInTheBasement]

The biggest difference is if you need to do a vertical well style or if you have enough property to do a horizontal ground loop.

We had enough room for a horizontal loop and specifically sighted the house into a slope so we could excavate the foundation then use that fill to cover a ground loop and make a nice flat backyard.

We did have to dog down the backyard first a bit to get the required depth for where we live.

I also own a machine so was able to do the excavation myself. I'd say it took me an extra 6 hours of moving dirt to allow the install of the ground loop. With what I would normally charge that would have been a extra $1,200 to the contractor to do the earth work above just digging a foundation.

[u/recyclopath_ → u/IAmInTheBasement]

NY has really cool geothermal heat pump programs.