Engineers develop 90-95% efficient electricity storage with piles of gravel | Hacker News Reader

Engineers develop 90-95% efficient electricity storage with piles of gravel

thecooldown.com

3 pointswesturner2 comments

> "The installed cost for our thermal storage system is less than $5-10 per kWh thermal, as compared to other energy-storage technologies, which are in the range of $150-$200 per kWh electric," [for 20 hours, after heating the piles of gravel to 932F ] at least initially? With greenhouses as the initial application

Very competitively efficient, but you don't need 932F for greenhouses?

/? oranges in Nebraska; https://youtube.com/results?sp=mAEA&search_query=Oranges+in+...

- "Nebraska retiree uses earths's heat to grow oranges in snow" in Alliance, NE, USA at -40F sometimes https://youtu.be/ZD_3_gsgsnk :

Passive, Net Zero, Carbon Sink solar geothermal half-buried greenhouse that produces citrus in the winter at a colder northern latitude

Geothermal air with 6" tubes, 8ft down, out 230ft (753) into the yard, blower, reflective sheeting on the south sloped back wall; est $25k build cost. 30F interval with no fans on in the winter. ;

Net zero greenhouses probably win UN SDG Indicator 13.2.2 Total greenhouse gas emissions per year; UN SDG Goal 13. Take urgent action to combat climate change and its impacts*

A New Zealand word for an [excavated] [semi-] underground greenhouse is "Walipini".

FWIU from YouTube, there's a new style of Northern Chinese greenhouse now in Canada: they build a big wall of clay/soil on one long side and lower a blanket over the entire greenhouse with a TODO HP motor in the evening to keep heat in the greenhouse at night. The wing shape makes it's easy to capture rainwater in a trough on just the one side.

Geodesic domes are very resilient, easy to assemble, and can also be semi-underground with vents at the top to actuate.

An aquarium heater can heat a tank of water to heat an arctic greenhouse.

Geodesic domes get so hot in the summer that it's necessary to hang cloth to shade and cool.

Also learned from YT South Korea: (JADAM JWA (Castille Soap) AND,) long stone seat and table fireboxes for greenhouse heat; but wood-burning has combustion byproducts so e.g. solar + wind electric (if geothermal is not feasible).

New EPA rules specify emissions limits for full-time wood-burning stoves; and so currently basically only Reburning and Catalytic Combustor stoves are legal in the US.

IDK what the effective $ per kWh is for solar and pumped air geothermal greenhouses?

Looks like there is at least one sand battery + hot water heater product to compete with heat pump water heaters that could also be sand (or gravel) batteries.

Multi-source heat pumps typically have an electric heat strip for very cold weather, and post-halving mining rigs also produce waste heat.

Apparently one can heat a pool (or a greenhouse water tank) with immersion mining rigs, but is there a sustainable fluid for industrial immersion cooling?

Agricultural Bunds (and buried unglazed water vessels) would probably work in NM, too; but which agricultural resources can process bunds instead of rows?

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