Earlier quoted context omitted.
Batteries are not cheaper than nuclear.
Batteries are getting cheaper quite rapidly, so don't get stuck in the dead past there.
Battery costs are literally rising
Geothermal may beat batteries for energy storage
251–260 of 293 posts
Re: Geothermal may beat batteries for energy storage
#252Earlier quoted context omitted.
> This reminds me a lot of the Earthship community … I was always wondering why … there are no water storages on the roof. All the standard Earthship designs I've studied do store their water on the roof, but they use batteries instead of water pumping to store unused electricity, because to run a conventional house's electrical systems at night you need to store tens of megajoules, and lifting water three meters onl…
> A 12-volt 24-amp-hour deep-cycle lead-acid battery goes for US$61 at retail, and that's nominally a megajoule; Is lead acid still purchased by anyone as a new system? That's $400 per usable kwh (unless the 50% DoD rule of thumb no longer applies?) where lithium has a vastly higher cycle count at $300/kWh Is there some upside (refurbishing lifecycle maybe)?
It's a good question! For years I've been hoping for the legendary Lithium-ion Crossover Event after which lead-acid batteries become obsolete for all purposes, but the auto parts stores in my neighborhood are still stubbornly stocking lead-acid starter batteries for some reason; so, too, the burglar alarm folks. Maybe the Crossover has already happened in the developed world, by which I mean China, but the news hasn't yet reached Argentina?
Re: Geothermal may beat batteries for energy storage
#253Earlier quoted context omitted.
This is not so complicated, you just need tanks with heat exchanger loops. The solar water heater input comes into your tank at the bottom and goes through a copper coil, giving you domestic hot water. _Some_ tanks will have a similar coil in the middle/top of the tank. What you can do is then run the cold return from your heating units through this coil. It will heat the radiator water before going to the fan coil u…
Thanks for your input. So I understand that heating the house requires much more hot water than what my solar heater can probably provide. In that case, connecting it to the radiator system is not so beneficial, and probably better to rely on a heat pump for the radiator water (the solar heater will not provide much help to justify connecting to it) Is that correct ?
Basically. There are all sorts of neat DIY examples of people using large solarthermal arrays and big storage tanks to provide adequate heat, but they’re major projects and custom.
For your system, what I’d potentially recommend is looking at a heat pump that can provide both domestic hot water -and- hot water for your radiators. They exist! Then, explain to your vendor/installer that you want a second heat exchanger in the tank for input from the thermosiphon. Then you would be providing solarthermal to both house heating and DHW— it won’t be enough, but it is theoretically better to apply that input across both loads, in a shared manner.
However, the question is cost. You’ve got a DHW system right now that works. To install a new system with a tank that can accommodate the thermosiphon input and provide DHW and radiant heat may be too expensive to be worth it.
A second thing for you to consider is the heating area of the radiators. Old radiators are designed for very hot water from boilers, ~180F. Heat pumps for radiant heating operate between about 95F-120F (lower is more efficient, but less responsive). Because of the lower temperature, they need a larger heating surface to deliver the same heat to the house. So, typically there’s a mix of larger European-style radiator panels and in-floor heat. In-floor heat is pretty great! A room at 65F feels like 72F when the floor is warm.
Re: Geothermal may beat batteries for energy storage
#254Earlier quoted context omitted.
Batteries are getting cheaper quite rapidly, so don't get stuck in the dead past there.
Battery costs are literally rising
Short term rise due to commodity prices, but shifts to LFP and other cheaper approaches will allow the dramatic long term price trend to continue.
https://about.bnef.com/blog/battery-pack-prices-fall-to-an-a...
If you look at PV there were similar "ah ha, costs have stopped falling!" moments in the past (mid 2000s, for example), but they didn't last long and were followed by even more dramatic cost declines. It's important not to be selective here, like climate change deniers are looking at global temperature data.
Re: Geothermal may beat batteries for energy storage
#255Earlier quoted context omitted.
This is not so complicated, you just need tanks with heat exchanger loops. The solar water heater input comes into your tank at the bottom and goes through a copper coil, giving you domestic hot water. _Some_ tanks will have a similar coil in the middle/top of the tank. What you can do is then run the cold return from your heating units through this coil. It will heat the radiator water before going to the fan coil u…
this is interesting. i have been told about using 319 steel insulated tank to store hot water, i was also told that this is a "pretty big deal in terms of cost" but i am willing to make that investment. here is my idea. 300Litre solar water heater+200Litre air source heat pump + storage + FCU.
I don’t have intuition for how large a 300L solar water heater would be — you mean the solar array on the roof, right?
If you have infloor radiant heat with concrete floors, then you might not need much water storage — the concrete provides heat mass. I would look more at deploying PV arrays for offsetting the electricity usage of the heat pump than adding more water storage and solarthermal. Solarthermal is technically more efficient in providing heat alone than equivalent electrical energy, but a heat pump uses that electricity to gather heat from outside, operating at 200-400% efficiency. Electricity is also more useful across the whole house, and of course is a great help in the summer for providing air conditioning.
Re: Geothermal may beat batteries for energy storage
#256Earlier quoted context omitted.
this is interesting. i have been told about using 319 steel insulated tank to store hot water, i was also told that this is a "pretty big deal in terms of cost" but i am willing to make that investment. here is my idea. 300Litre solar water heater+200Litre air source heat pump + storage + FCU.
I don’t have intuition for how large a 300L solar water heater would be — you mean the solar array on the roof, right? If you have infloor radiant heat with concrete floors, then you might not need much water storage — the concrete provides heat mass. I would look more at deploying PV arrays for offsetting the electricity usage of the heat pump than adding more water storage and solarthermal. Solarthermal is technica…
yeah, the problem with infloor is that the floor is already laid down so i would have to redo the flooring for all rooms.
my use case is winter nov-feb which occasionally has snow, some year there is 0 snow, some year there is 12 inches, usually inbetween.
electricity from the grid is often down during this time period but when it does come, we could use the heat pump to heat up the "storage". 300L water heater in this case means 300L/day of water heater (yeah, rooftop solar water)
the storage can be anything, 500L, 1000L, 2000L, that is cost dependent only. if we feel more storage is needed, we just add another tank
heat pump is like 200L/hour so yeah
Re: Geothermal may beat batteries for energy storage
#257Earlier quoted context omitted.
> Why there are no water storages on the roof. Quick math - 100 gallons of water 15 meters up off the ground has enough potential energy to run a microwave for 30 seconds. Gravitational storage is pathetically weak. It only makes sense on massive, massive scales. In a residential setting, the storage will never outweigh the extra cost and risk of having so much water on your roof.
One minor but interesting exception - farmers have historically often put domestic water tanks on top of towers to ensure even water pressure. Direct pumping leads to cycles where the pressure in the system rises and falls as the pump cycles on and off, which is very unpleasant if you’re trying to take a shower! I believe modern off-grid home water pumps use more sophisticated motor control to avoid the need for the…
I thought the point of water tanks is that one needs a simpler / weaker pump to maintain the water pressure.
i.e. if you want to maintain water pressure X, with a pump you need something that can push X, but with a tower, you just need a pump that can keep the tower full over the course of a more length period and just has to pump at the average of what it takes to keep it full over the course of that longer period (i.e. the average pressure needed to maintain the tower is less than the pressure you need to provide).
Re: Geothermal may beat batteries for energy storage
#258Earlier quoted context omitted.
> A 12-volt 24-amp-hour deep-cycle lead-acid battery goes for US$61 at retail, and that's nominally a megajoule; Is lead acid still purchased by anyone as a new system? That's $400 per usable kwh (unless the 50% DoD rule of thumb no longer applies?) where lithium has a vastly higher cycle count at $300/kWh Is there some upside (refurbishing lifecycle maybe)?
It's a good question! For years I've been hoping for the legendary Lithium-ion Crossover Event after which lead-acid batteries become obsolete for all purposes, but the auto parts stores in my neighborhood are still stubbornly stocking lead-acid starter batteries for some reason; so, too, the burglar alarm folks. Maybe the Crossover has already happened in the developed world, by which I mean China, but the news hasn…
There's really no benefit to lithium batteries in a car. They perform much worse in the cold, and they are more expensive. You don't cycle your car battery 100-0-100 so the fact that the useable capacity of lead batteries is lower doesn't matter.
Re: Geothermal may beat batteries for energy storage
#259Earlier quoted context omitted.
> A 12-volt 24-amp-hour deep-cycle lead-acid battery goes for US$61 at retail, and that's nominally a megajoule; Is lead acid still purchased by anyone as a new system? That's $400 per usable kwh (unless the 50% DoD rule of thumb no longer applies?) where lithium has a vastly higher cycle count at $300/kWh Is there some upside (refurbishing lifecycle maybe)?
It's a good question! For years I've been hoping for the legendary Lithium-ion Crossover Event after which lead-acid batteries become obsolete for all purposes, but the auto parts stores in my neighborhood are still stubbornly stocking lead-acid starter batteries for some reason; so, too, the burglar alarm folks. Maybe the Crossover has already happened in the developed world, by which I mean China, but the news hasn…
I'm not sure if you're being facetious, but in thinking about it I think you've pointed out the remaining advantages. Current from lithium batteries has to go through a bms (and thus you have to build them to a current rating, even if your cells are 5C the cost of BMS may make lead acid cheaper) and they have low temperature issues so I can see them being useful in current limited situations and in situations where not thinking about them or the weather too much is more important than capacity.
I can't see this recommendingnlead acid in a capacity limited application unless it's a situation like Australia where half of the local shops are pricing them at 2012 rates.
Re: Geothermal may beat batteries for energy storage
#260Earlier quoted context omitted.
It's a good question! For years I've been hoping for the legendary Lithium-ion Crossover Event after which lead-acid batteries become obsolete for all purposes, but the auto parts stores in my neighborhood are still stubbornly stocking lead-acid starter batteries for some reason; so, too, the burglar alarm folks. Maybe the Crossover has already happened in the developed world, by which I mean China, but the news hasn…
I'm not sure if you're being facetious, but in thinking about it I think you've pointed out the remaining advantages. Current from lithium batteries has to go through a bms (and thus you have to build them to a current rating, even if your cells are 5C the cost of BMS may make lead acid cheaper) and they have low temperature issues so I can see them being useful in current limited situations and in situations where n…
I'm not being facetious, I'm just trying to understand the discrepancy. Your explanation isn't it: battery management systems do not account for a major part of the cost, we don't have low temperatures in Buenos Aires, and the auto parts stores are not selling the lead-acid batteries as specialty parts to people who drive in from Patagonia to replace their car batteries, similar to engine block heaters.
sbp looked into the issue and it seems that lead-acid is still cheaper.
https://justcatamarans.net/lithium-vs-lead-acid-batteries-co... claims that the Li-ion batteries they are trying to sell you are still more expensive.
https://news.energysage.com/lithium-ion-vs-lead-acid-batteri... says, "The one category in which lead acid batteries seemingly outperform lithium-ion options is in their cost. A lead acid battery system may cost hundreds or thousands of dollars less than a similarly-sized lithium-ion setup."
https://www.pv-magazine.com/2021/09/02/lithium-ion-vs-lead-a... says, "Citing previous studies, the researchers said that, for stationary energy storage, lead-acid batteries have an average energy capital cost of €253.50/kWh and lithium-ion batteries, €[1555]/kWh, and that their total average power cost is €333.50/kWh and €[2210]/kWh, respectively."
In the units I was using above, those costs are US$68.30/MJ, US$419.0/MJ, US$89.86/MJ, and US$595.5/MJ.
So it seems like the answer is that, yes, lead-acid is still purchased by some people as a new system, because it's still cheaper than lithium-ion. Probably what led to the error is that lead-acid in Argentina is more expensive than lithium-ion in China, or wherever Schroederingersat's at.