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California utility augments 1,800 air conditioning units with “ice battery”
A Santa Barbara-based company called Ice Energy has partnered with NRG Energy to deliver 1,800 “ice batteries” to commercial and industrial buildings served by electric utility Southern California Edison (SCE). The units are expected to reduce air conditioning bills by up to 40 percent and eliminate 200,000 tons of CO2 over the next 20 years.
Ice Energy has been building ice-based cooling systems since the early 2000s. Much like pumped storage or compressed air “batteries,” Ice Energy essentially stores electricity by drawing power from the grid at non-peak times to freeze water in a special container. Then at peak times, when the cost of electricity is high and grid operators are struggling to keep up with demand, Ice Energy’s systems kick in and use that block of ice to cool the space that the air conditioning unit normally serves.
(Score: 4, Informative) by butthurt on Sunday May 07 2017, @12:57AM (6 children)
> WASTING energy, not saving energy, overall
A fair bit of California's electricity is from wind and solar, which are intermittent. If more electricity is being produced than is needed, the excess production goes to waste:
On March 27[, 2016], a sunny day, some solar farms had to shut down because there was more power on the grid than Californians were using.
-- https://ww2.kqed.org/science/2016/04/04/what-will-california-do-with-too-much-solar/ [kqed.org]
These ice-making systems would instead do something useful with that electricity.
Another consideration is thermodynamic efficiency. These systems will be able to run at night, using less energy than if they were running during the day because the outside air is ordinarily cooler at night than it is during the day. Of course, the proper comparison is to more conventional cooling systems, and I don't have the expertise to make that comparison.
The peaking plants in California burn natural gas. The article I linked explains it, although not very well. In the comments, MITDGreenb says that they are seldom shut down because doing so creates a great deal of wear on the machinery. Instead, he says, they are kept running, but at much less than their full capacity--and much less than their full efficiency. He likens it to a car idling. Little electricity is produced, but a fair bit of fuel is needed. With enough of these ice-making systems, peak demand might be reduced enough to close one or more peaking plants. The amount of electricity consumed might even be greater than otherwise, but the amount of natural gas burned would be less.
(Score: 1, Insightful) by Anonymous Coward on Sunday May 07 2017, @01:29AM (2 children)
Minus: Lower efficiency due to the usage of storage mechanism.
Plus: Greater efficiency at night time due to generators operating at a higher capacity (i.e., higher efficiency)
Plus: Alleviating daytime peak load demand.
Minus: Added cost of distributed installation/maintenance.
So we will just to have to try and see how they will sum out in the real world.
(Score: 2) by butthurt on Sunday May 07 2017, @03:22AM (1 child)
Sorry if I was too long-winded. You left out one point: for the same initial and final indoor temperatures, it takes less energy to run an air conditioner when the outside temperature is cool rather than hot (a plus). I left out a related point that I meant to make: normally we don't cool buildings below the freezing point of water. Theoretically, we expect to use more energy if we make ice then melt that ice to cool a room to a comfortable temperature than to just cool the room directly to that same temperature (a minus).
https://en.wikipedia.org/wiki/Thermal_efficiency#Carnot_efficiency [wikipedia.org]
(Score: 0) by Anonymous Coward on Sunday May 07 2017, @04:09AM
Not long-winded, I was just summarizing the factors brought up. And the point(s) you elaborated would be included in the reduced efficiency due to the storage mechanism.
And I am sure there are other factors not mentioned.
(Score: 2) by GungnirSniper on Sunday May 07 2017, @01:40AM
That's induced demand. We shouldn't build any more power plants because low prices will encourage use and pollution.
Tips for better submissions to help our site grow. [soylentnews.org]
(Score: 2) by requerdanos on Sunday May 07 2017, @01:46PM (1 child)
A fair bit of California's electricity is from wind and solar, which are intermittent. If more electricity is being produced than is needed, the excess production goes to waste:
On March 27[, 2016], a sunny day, some solar farms had to shut down because there was more power on the grid than Californians were using.
...These ice-making systems would instead do something useful with that electricity.
Although that day was a Sunday and therefore classified as off-peak all day, most days, the summer off-peak use is going to be 11pm - 8am when the solar farms are already shut down. It seems to be basically an at-night system, which mostly rules out solar.
Sources of electricity generation in CA [eia.gov] during the night-time seem to be Natural Gas, hydroelectric, nuclear, and renewables like wind, in that order.
So what it seems is that, with solar off the table at night, a higher percentage of the energy available (by whatever margin) is going to be the creating-carbon-exhaust variety, and since the system can't be 100% efficient, it is going to use more overall energy than just running the air conditioner. (Instead of 'wasting energy'--if it's doing work it arguably isn't wasted--I should have said 'using more energy' above).
(Score: 2) by butthurt on Sunday May 07 2017, @11:39PM
> [...] summer off-peak use is going to be 11pm - 8am [...] It seems to be basically an at-night system [...]
The article says:
What the utility gets in exchange for its discounts is control over when the IceBears are turned on and off [...]
which seems to mean control over when the ice is melted. I see nothing that contradicts what you said; an earlier article says specifically that the units were intended to be run "at night"
https://cleantechnica.com/2014/11/22/25-mw-ice-energy-storage-southern-california-edison/ [cleantechnica.com]
Just as a conventional air conditioner can run during the day--albeit less efficiently than at night--these could run during the day if their controller had been designed to allow it. Again, I see nothing that says they were designed that way, which is too bad: solar energy used for freezing in the morning could lessen electric use in the afternoon and evening, when the load is highest in the summer:
https://www.eia.gov/todayinenergy/detail.php?id=19111 [eia.gov]
> [...] since the system can't be 100% efficient, it is going to use more overall energy than just running the air conditioner.
You seem to disregard the last two paragraphs of my previous comment (#505638): cooling at night can be more efficient than cooling during the day; running a gas-fired (or coal or nuclear) power plant at full capacity around the clock is more efficient than using it for peaking. Overall energy ought to include the energy embodied in the natural gas. You seem to be considering just the electric energy used, which could be higher with the Ice Bear but not necessarily (because of the Carnot thing).