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Geothermal may beat batteries for energy storage

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Re: Geothermal may beat batteries for energy storage

#231

Post by Schroedingersat »

kragen wrote: post #211
cookiengineer wrote: post #68

Earlier quoted context omitted.

This reminds me a lot of the Earthship community in the middle of the desert, which always focusses on smart ways of reusing water for different purposes, and by not wasting water as much as possible. The houses usually have a clean/grey/blackwater + a rainwormbox system to process fecals and reuse it for growing plants. Their air conditioning system is basically just a pipe in the ground where the hot air flows thro…

> 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)?

Re: Geothermal may beat batteries for energy storage

#232

Post by mschuster91 »

Schroedingersat wrote: post #82
mschuster91 wrote: post #51

Earlier quoted context omitted.

> Solar, if you use more than ~1% of the land you're radically altering the albedo and habitat Both of these may actually turn out to be beneficial. Putting up solar panels above agricultural land ("Agri-PV") is not just avoiding clobbering up arable land with PV panels, but also has benefits for the plants [1]: they need less water because less sun directly hits the plants and heats up the soil which means both more…

Agri-PV is one way of using the thermal budget (and a great one from a habitat-harm perspective as it causes a net reduction in human-occupied land). The albedo problem is the opposite of what your are thinking as it is another source of radiative forcing from putting a mostly black thing in the sun. A Shockley-Queisser limited solar panel mostly only reflects IR. So where your plants/dirt might have an albedo of 0.3…

> Putting the panel in existing (light coloured) desert is much worse because deserts have an albedo around 0.4-0.6 so you are making 400-550W of new heat for your 200-300W of work.

Yeah, but the heat doesn't penetrate to the ground any more, which should help with water retention?

Re: Geothermal may beat batteries for energy storage

#233

Post by Schroedingersat »

mschuster91 wrote: post #232
Schroedingersat wrote: post #82

Earlier quoted context omitted.

Agri-PV is one way of using the thermal budget (and a great one from a habitat-harm perspective as it causes a net reduction in human-occupied land). The albedo problem is the opposite of what your are thinking as it is another source of radiative forcing from putting a mostly black thing in the sun. A Shockley-Queisser limited solar panel mostly only reflects IR. So where your plants/dirt might have an albedo of 0.3…

> Putting the panel in existing (light coloured) desert is much worse because deserts have an albedo around 0.4-0.6 so you are making 400-550W of new heat for your 200-300W of work. Yeah, but the heat doesn't penetrate to the ground any more, which should help with water retention?

Local effects vs. global effects.

You might make your desert nice, but you're still doing a climate change if you try to install more than a few hundred TW of solar panels.

Ideally you make the desert nice and then take a chill pill before covering all of the deserts and settle for somewhere in the range of 2-100kW per human as a steady state economy powered by a mix of wind, solar, geothermal, and maybe some nuclear.

Re: Geothermal may beat batteries for energy storage

#234

Post by 2Gkashmiri »

jonstewart wrote: post #221
mderazon wrote: post #177

Earlier quoted context omitted.

I am currently looking to do something similar. I have zero heating in my house at the moment and have a 300L (65 gallon) thermosiphon solar water heater [1] (tank plus panels all in one system) that gives me plenty hot sanitary water. I am looking to install an hydronic fan coil [2] radiator in my rooms and need water to heat them - I thought to use the excess heat from the solar heater to supply hot water to the fa…

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.

Re: Geothermal may beat batteries for energy storage

#235

Post by pfdietz »

jasonwatkinspdx wrote: post #210
cookiengineer wrote: post #68

Earlier quoted context omitted.

This reminds me a lot of the Earthship community in the middle of the desert, which always focusses on smart ways of reusing water for different purposes, and by not wasting water as much as possible. The houses usually have a clean/grey/blackwater + a rainwormbox system to process fecals and reuse it for growing plants. Their air conditioning system is basically just a pipe in the ground where the hot air flows thro…

The efficiency of pumped hydro storage depends heavily on the height difference involved. There's not that many suitable sites, most have been developed already. It's not a technology that scales down well other than vanity projects. Rooftop cisterns are very common globally, usually places where the water utility if it exists is unreliable. A huge number of humans get their water from a truck that comes by weekly or…

There are not many suitable sites on existing rivers, but the potential off river PHES resource is vast. This involves building two reservoirs, charging them with water brought in from elsewhere, then cycling the water back and forth. Additional water will be needed only to make up for evaporation and seepage, but this amount is at least an order of magnitude less than the water evaporated by a nuclear power plant of the same time-averaged power.

Re: Geothermal may beat batteries for energy storage

#236

Post by pfdietz »

xyzzyz wrote: post #208
teucris wrote: post #93

Earlier quoted context omitted.

Huh. We have a 1:1 credit system here in Washington.

This is an enormous subsidy to residential PV. Electricity wholesalers would love to be able to sell it to the grid at retail prices, like you are. Instead, they sell it for something like a quarter of retail price. This huge subsidy is only sustainable for so long as the PV penetration is low in residential market.

Yes. Even just being able to connect to the grid and only pay for the energy consumed is a subsidy. There is a large fixed cost to provide the connection and guarantee power will be available on it when demanded.

Re: Geothermal may beat batteries for energy storage

#237

Post by pfdietz »

smileysteve wrote: post #130
londons_explore wrote: post #83

Earlier quoted context omitted.

Even a modern air source heat pump typically doesn't beat gas for $/kwh. Even in europe where gas prices are sky high, electricity still costs more when you look at the seasonal efficiency of heat pumps, which is typically advertised around 4.4, but various studies show that in most real world scenarios you typically won't reach the quoted lab numbers, so expect to get more like 2.5-3.0. Study: https://www.sciencedir…

This seems like a (regulated) pricing error. There should be no economic way that a high efficiency turbine produces and distributes electricity to heat homes at a greater than 1:1 ratio compared to storing, pressurizing, and delivering, then burning in irregularly maintained consumer homes. Likely the error is that gas pipes to the house are subsidized (albeit the electrical likely is too, with heat pumps and induct…

A furnace causes a very large second law loss, converting chemical energy to low grade heat. If that gas is used to drive turbines, and the work produced used to drive heat pumps, much of this entropy generation is avoided.

A home gas-driven heat pump could be a better option from an efficiency standpoint, but those are not widely available, probably for cost and reliability reasons.

Re: Geothermal may beat batteries for energy storage

#238

Post by pfdietz »

dahfizz wrote: post #195
smileysteve wrote: post #183

Earlier quoted context omitted.

But gas turbines should be more efficient than a burner under a boiler or a burner in a furnace. Yes, solar, wind, hydro, nuclear should be cheaper per unit (coal is not usually cheaper than gas in the US)

95% efficient gas furnaces are the norm for newer houses[1]. Getting electricity out of gas is fundamentally harder than getting heat out of it. [1] https://iwae.com/resources/articles/95-afue-gas-furnace-work...

There is a large second law loss even in a "95% efficient" furnace. A gas-fired heat pump would have efficiency much higher than that.

Re: Geothermal may beat batteries for energy storage

#239

Post by pfdietz »

Schroedingersat wrote: post #198
kansface wrote: post #149

Earlier quoted context omitted.

Doesn’t the nuclear heating happen regardless of us harnessing the energy or not?

Unenriched uranium will fission eventually, but you're talking trillions of years. In a fission reactor, the U238 atoms are placed close enough to a minority of U235 atoms and to each othekr that neutrons from one fission will trigger the next at a rate just short of running away exponentially. There are some ore bodies that are concentrated enough to fission faster, but they are rare (and not the uranium that is typ…

The uranium undergoes alpha decay first. Alpha decay is not fission.

Re: Geothermal may beat batteries for energy storage

#240

Post by distances »

jonstewart wrote: post #222
distances wrote: post #192

Earlier quoted context omitted.

Interesting. Last winter my parents' rooftop solar had zero output until April, as it produces nothing until all the panels are clear of snow. Granted their installation is at a fixed angle that matches the roof, and this is in the Nordics. During summer months the production mostly covers and partly exceeds their use, but the sell price is so much lower that it doesn't even begin to pay for the rest of the year. But…

So much of this discussion depends on where you are. In the US, a typical solar installation is on the pitched roof of a house. When the sun comes out, the dark roof and PV panels heat up, and the snow slides off. Rowhomes or apartment buildings in a city might have flat roofs with panels mounted on racks, but most US cities won't get enough snow often enough for this to be a problem.

My parents do have a traditional pitched roof. Winter sun is not warm enough to warm up anything, even if dark, until late winter. Plus the color of course is white if it's covered in snow :) Yeah very much location dependant.
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