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US Government funds pilot project for heated sand energy storage
- reify 3y agoI love this idea I have been following the progress of sand batteries. So much so that I actaully made one at home. https://hackaday.com/2022/11/21/making-a-do-it-yourself-sand-battery/ https://hackaday.com/2022/11/21/making-a-do-it-yourself-sand... I made some changes to this idea. I used a 12V supply from an old PC power supply to run the heat element in the sand. I used some course pool filter sand that I use for my aquariums. I have a very chilly hallway with no radiator between my lounge and main entrance door. It did work. Raised the temperature from 62F to a modest 70F. It took a few days to warm through and remain constant. I see there are developments in Scandinavia to heat entire towns. This is the good science I like to see.
- ZeroGravitas 3y agoI'm dubious about all long duration energy storage systems (LDES). I feel their addressable market gets squashed between a) simply building more renewables and short term battery storage, both of which are reducing in cost due to massive buildout, b) making chemicals from renewable energy (i.e. green hydrogen, that then gets used as a building block for Ammonia or hydrocarbons). As long as the former is able to cheaply eat marketshare then you can just use the fossil fuels it displaces in the hard to decarbonise markets and still come out ahead financially and in terms of carbon. The latter can be used in jumbo jets or whatever, but also in fairly standard turbines for electricity production if needed, but emphasis on "if" because if you need it just as insurance against unpredictable demand/weather, then it's a plus point if you can just sell it to farmers, airlines or factories once you get to spring, and the physical storage already exists on a large scale for those purposes. I think this already makes pumped hydro financially dubious, never mind more theoretical ideas. The timeshifting of electrical heat demand for industry is another market nibbling away at this, and might be another use for the fluidized bed and sand storage part though.
- bell-cot 3y ago> The sand used in the thermal energy storage (TES) system could be heated to the range of 1,100 C using low-cost renewable power. [...] when electricity is needed, the system will feed hot sand by gravity into a heat exchanger, which heats a working fluid, which drives a combined-cycle generator. So this is definitely not a "bury your heating coils in a sand dune, then connect..." technology. Quartz melts (per Wikipedia) at 1,713 C. Hotter would obviously be more efficient (basic thermodynamics) - but from the linked govt. report, it sounds like getting usefully hotter would lead to excessive technical problems. Beyond sourcing the sand (a real issue in many places), this tech sounds incredibly benign, environmentally. Zero-ish rare elements / nasty chemicals / emissions. And the worst-case "melt-down" leaves just a pile of burning-hot sand. Edit: IANAME (not a Mech. Engineer), but that govt. technical report looks like great stuff if you're seriously into energy storage tech, or just an amateur gearhead. Direct link: https://www.nrel.gov/docs/fy23osti/84728.pdf https://www.nrel.gov/docs/fy23osti/84728.pdf
- orev 3y agoSand-sourcing issues are typically related to types of sand required for special applications, such as in concrete or silicon wafer production that needs very specific types or shapes of the grains. This kind of application would probably work with “regular” sand that’s unsuitable for those special purposes, and also happens to be the most common type of sand.
- smallmancontrov 3y agoHuh, it intuitively seems like piping working fluid to the sand ought to be easier than moving the sand to the working fluid. Is the moving-sand approach fundamentally desirable thing (I can't imagine why) or is it just a simplification for the proof of concept?
- iamthemonster 3y agoNah it's nuts to mobilise the sand as a working fluid. The more mature design option seems to be refractory brick for heat energy storage, with piping running through it where you can raise steam. Running a steam turbine generator is generally seen as uneconomic due to the very low round-trip efficiency, and heat storage usually follows the principle of "if you store it as heat, use it as heat".
- HPsquared 3y agoThermal storage works nicely with solar thermal plants. Not so good for direct electricity storage though.
- bell-cot 3y agoPretty inefficient, yes. Thermodynamics is a harsh mistress. But if the other choice is "throttle down the wind farm, because the grid doesn't need that much power" - then a really cheap/simple/safe (but inefficient) storage tech could prove pretty useful.
- seanmcdirmid 3y agoHow does this compared to pumped storage?
- pfdietz 3y agoModern pumped hydro might have a RTE of 80%.
- non-chalad 3y agoYou can pump sand by bubbling compressed air through it. 1. https://www.youtube.com/watch?v=My4RA5I0FKs https://www.youtube.com/watch?v=My4RA5I0FKs
- clort 3y agoseems to me that this would result in heat-loss as the air is heated quickly then ejected from the mass. perhaps the bubbled gas doesn't hold a significant amount of heat though? (but if it did, it could be used to extract the heat without pumping the sand...)
- pfdietz 3y agoOne can get higher round trip efficiency (practically, perhaps 65%) using pumped thermal storage. Here, one uses some thermal cycle in reverse to separate "cold" and "hot", then reverse that to discharge. This also reduces the maximum temperature needed to maybe 500 C, below the creep limit for cheap steel. The cold end would be maybe -100 C, stored in something like liquid hexane.
- ejb999 3y agoI am really intrigued by using sand for energy storage - what I don't get (not my field) is given a typical 2000sf house, located in the colder part of the country as an example, how much heat could be stored for how long? i.e. is it even feasible to use solar panels to power resistance heaters all spring/summer/fall, to save up enough heat to keep a house warm for the entire winter? if so, how many panels would you need and how big a sand battery would it take. I am not planning on doing this, but explaining it on a scale that I can relate to would be helpful, because I know, for example, that said house can store a winter's worth of heat in a 1000 gallon oil tank, or small woodshed big enough for 6 cords of wood.
- ceejayoz 3y agohttps://en.wikipedia.org/wiki/Seasonal_thermal_energy_storage https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storag... > In Alberta, Canada, the homes of the Drake Landing Solar Community (in operation since 2007), get 97% of their year-round heat from a district heat system that is supplied by solar heat from solar-thermal panels on garage roofs. This feat – a world record – is enabled by interseasonal heat storage in a large mass of native rock that is under a central park. The thermal exchange occurs via a cluster of 144 boreholes, drilled 37 metres (121 ft) into the earth. Each borehole is 155 mm (6.1 in) in diameter and contains a simple heat exchanger made of small diameter plastic pipe, through which water is circulated. No heat pumps are involved. That development is 52 homes. They are presumably engineered to be highly energy efficient and it's not a perfect comparison to sand, but it's less than I'd have imagined.
- giarc 3y agohttps://www.cbc.ca/player/play/1.7155409 https://www.cbc.ca/player/play/1.7155409 I live in Calgary and have seen a few articles about Drake Landing recently.
- ulnarkressty 3y agoStoring heat in bedrock sounds like a good idea, but there are risks, e.g. https://www.thelocal.de/20170818/this-historic-german-town-is-falling-apart-in-slow-motion-catastrophe https://www.thelocal.de/20170818/this-historic-german-town-i...
- xnx 3y agoDoes this differ in design from the Finish sand battery from 2 years ago: https://news.ycombinator.com/item?id=32006791 https://news.ycombinator.com/item?id=32006791
- pfdietz 3y agoYes, this involves higher temperature (the sand is stable up to ~1200 C) and transfer of heat from the sand to a working gas by means of Babcock & Wilcox's fluidized bed heat exchanger technology. This is a neat idea that intimately mixes the gas and sand for very rapid and compact heat transfer. Using resistive heaters, round trip efficiency (back to electricity) is estimated to be around 52%.
- michael1999 3y agoThe Finnish system is just heat->heat. They generate heat when the wind is blowing, and inject heat back into the district system when it isn't. Super simple - resistive heating, and passive heat transfer. This system produces electricity. Exciting, but much fancier.
- dubcanada 3y agoA stirling engine can generate heat from electricity, such as those used in MicroCHP, you can burn wood, produce heat, and generate electricity from that heat. You could do the same with a pile of sand. You just need to pipe liquid through the sand, and a supply of cooler water.
- jarito 3y agoUndecided did a couple of videos on this technology. It seems quite useful for heat storage - as other commenters have noted, it isn't that efficient for pure electric <-> electric storage. * How a Sand Battery Could Change the Energy Game - https://www.youtube.com/watch?v=G6ZrM-IZlTE https://www.youtube.com/watch?v=G6ZrM-IZlTE * Sand Batteries for Home Usage - https://www.youtube.com/watch?v=KVqHYNE2QwE https://www.youtube.com/watch?v=KVqHYNE2QwE
- deleted 3y ago[deleted]
- dagurp 3y agoI like this one too https://youtu.be/KVqHYNE2QwE?si=GM80NBsE_Ms8oT-n https://youtu.be/KVqHYNE2QwE?si=GM80NBsE_Ms8oT-n
- pfdietz 3y agoI have wondered if this technology could be used in open loop mode where the sand is replaced with some material that you want to thermally process. For example, olivine particles that become more reactive with CO2 (for mineral carbonation for CO2 sequestration) after being heat treated. Run the particles though once and use them afterwards.
- nick238 3y agoFeed in calcium carbonate, heat it up and sequester the CO2, and use the hot calcium oxide once then ship it off to the cement plant. Or, how about taking an existing cement plant and have it use the air heat-exchanger/turbine/generator setup described in this project to recover the energy in the red-hot clinker? I assume they'd have some sort of heat exchanger system already to preheat feedstock using the outflow, however?
- retrac 3y agoHeat storage has an aspect that was counterintuitive to me, but follows from basic geometry. It benefits greatly from large scale, since the ratio of the volume to surface area [1] decreases the larger you make a container. Accordingly, if a heat tank is large enough, the surface area becomes negligible relative to its volume, and it, in effect, becomes well-insulated by its own mass. For really big tanks, like might be used for an entire town to heat itself over a winter, practical self-discharge rates can be just a few % per month, which is better than most rechargeable battery technologies. [1] https://commons.wikimedia.org/wiki/File:Comparison_of_surface_area_vs_volume_of_shapes.svg https://commons.wikimedia.org/wiki/File:Comparison_of_surfac...
- chii 3y ago> better than most rechargeable battery technologies you can't compare heat storage to electricity, because you can't directly use heat for anything else other than for heating, where as electricity can be used to perform motion. If you used heat storage as a battery, there's an additional loss when converting to electricity. However, if the heat is cheap/free during summer, storing it for winter is a no brainer.
- datameta 3y agoThe sand is gravity-fed into a heat exchanger which transfers the heat to a fluid that drives a combined cycle turbine, in this case. I'm curious what the conversion loss is here. To add to that, what is the energy expenditure of building the battery compared to sand containment plus heat exchanger and turbine - i.e. mining, refining, transport, manufacture, delivery?
- robviren 3y agoGas turbine efficiency targets for combined cycle are targeting 65%, so loss is at least 35%. To me I the loss sucks, but if it can be cheap to build and maintain it matters less. If solar is the energy source and that gets driven cheap enough then that loss could be acceptable.
- nick238 3y agoLove the idea. Hate the acronym...ENDURING, short for "Economic loNg-DURation electrIcity storage by using low-cost thermal energy storage aNd hiGh-efficiency power cycle"? ELDESbULCTESaHEPC.
- scotty79 3y agoIt could be interesting to burry heating coils in the ground under the house and maybe dig deep, insulated petimeter foundation to better keep the heat inside. Power them with solar of course at times of negative prices. Or dig out a deep cellar, insulate on the sides and a the bottom against heat loss and moisture and put back the earth you dug out with heating element in the center. You don't even have to insulate wires that go through earth to the heating element because electricity passing through earth will get turned to heat as well. It might be nice additional heating for cooler climates. If you dug deep enough to have actual cellar on top of that you'd have a very warm cellar, you could put underground swiming pool there.
- throwitaway222 3y agoSeems to me that direct battery storage research is a much much much MUCH better use of government research funding. Sure if you want to use sand heat holders for heating houses, fine.. but for conversion to electricity? bleh
- pfdietz 3y agoBatteries are likely better for diurnal storage, but the per-energy capital cost of the sand silos ($2/kWh(th))) would be really hard to beat with batteries, so for longer periods this could be superior.
- leecarraher 3y agoit seems the primary benefit for sand over water, is a 1:10 operating temp vs. 5:1 specific heat. So it depends on whether the added complexity of working with a hotter, solid is worth not having to build a facility that is 2x bigger. Are there other benefits I'm missing, or is this concrete block gravity storage vs pumped water storage, all over again?
- pfdietz 3y agoIf the goal is conversion back to electrical energy, the high temperature is a huge advantage.
- nick238 3y agoComparing water's 4.18 kJ/kg-K * ~75 K (25 °C -> 100 °C) to the sand's 1.1 kJ/kg-K * 900 K? I think you can (or it's easier) get more useful work out of a lesser amount of hotter stuff, even if the thermal energy or total heat is the same. Unsure of that, I don't know what the specific principle is. I'd vaguely gesture at the 2nd law of thermo as if I poured a cup of boiling water into a pot of room-temperature water, the total heat leaving the pot would wind up being the same as the heat leaving the cup, but less useful?
- NegativeK 3y agoSand doesn't leak down or up (via evaporation) nearly as much. It's also far less of a precious resource and non-corrosive, compared to the most common version of water.
- hamilyon2 3y agoWhat if we grind asteroids and send bags of sand from orbit? Sand will overheat while falling giving us free energy and sand. Sand is valuable.
- bugbuddy 3y agoWhatever you are on, I need some of it. It must be good.
- spywaregorilla 3y agoAlso an unstoppable onslaught of kinetic weapons
- kylehotchkiss 3y agoLike a giant Turkish coffee stove?
- pfdietz 3y agoHere are some informative slides on the technology from 2021: https://arpa-e.energy.gov/sites/default/files/2021-03/07%20Day1-Zhiwen%20Ma_NREL.pdf https://arpa-e.energy.gov/sites/default/files/2021-03/07%20D... Previously linked at https://news.ycombinator.com/item?id=28451131 https://news.ycombinator.com/item?id=28451131
- spxneo 3y agoI go to the beach fill up 50 gallon drums with it and then pipe hot water through it so that you can enjoy heat without electricity or gas. im obsessed with it. i love the way it feels on my body. i take warm sand baths with it. i have cold feet so i use nylon socks, fill it with sand providing endless massage and keeping it warm. ive yet to try different types of sand from other regions but Canadian beach sand does the job.
- dsp_person 3y agoi can't tell if you are trolling or not
- spxneo 3y agowhy would i be trolling?
- dsp_person 3y agoso maybe someone will try putting sand in their socks
- spxneo 3y agoi dont understand it feels really good
- kaliszad 3y agoUsing heat for energy storage and then converting back to electricity are ok if you don't care about cost of electricity, the facility or the maintenance. In basically all other cases they are some of the worst ideas. We have much better technologies that are known for the last ~50 years. They are simple, they do work and have volumetric energy density within striking distance of fossil fuels however don't include carbon. Just reading the expired US patents would reveal that. I guess there are worse things to invest into but come on, we teach the physics needed to comprehend why this is a bad idea in high school.
- newzisforsukas 3y agohttps://polarnightenergy.fi/technology https://polarnightenergy.fi/technology
- bitsinthesky 3y agoWith such cheap solar panels soaking up summer sun combined with this storage, winter heating could get really efficient.