White-Hot Blocks as Renewable Energy Storage?
In five years, operating a coal or natural gas power plant is going to be more expensive than building wind and solar farms. In fact, according to a new study by Bloomberg New Energy Finance, building a new solar farm is already cheaper than operating coal and natural gas plants in many regions of the world.
Yet a full shift to intermittent energy sources desperately calls for low-cost, reliable energy storage that can be built anywhere. Some nascent startups believe the answer lies in the process that lights up toaster coils by electrically heating them to scorching temperatures.
Antora Energy in Sunnyvale, Calif., wants to use carbon blocks for such thermal storage, while Electrified Thermal Solutions in Boston is seeking funds to build a similar system using conductive ceramic blocks. Their vision is similar: use excess renewable electricity to heat up the blocks to over 1,500°C, and then turn it back to electricity for the grid when needed.
To beat the cost of the natural gas plants that today back up wind and solar, storing energy would have to cost around $10 per kilowatt-hour. Both startups say their Joule heating systems will meet that price. Lithium-ion batteries, meanwhile, are now at approximately $140/kWH, according to a recent study by MIT economists, and could drop to as low as $20/kWH, although only in 2030 or thereafter.
(Score: 0) by Anonymous Coward on Friday June 25 2021, @08:00AM (1 child)
So, we wait? By 2030s the gas plants will start to need replacement and then we can just put the cheap storage there instead. What's the problem? You can't fix everything by tomorrow!
(Score: 3, Insightful) by sjames on Friday June 25 2021, @05:54PM
If every gas fired plant had been built yesterday, you would have a point, but in fact, there are some reaching end of life now. If we wait until 2030 to start, we will end up stuck with a bunch of nearly new gas plants that won't retire naturally until 2060.
(Score: 4, Interesting) by shortscreen on Friday June 25 2021, @08:59AM (8 children)
Lithium-ion batteries and pumped storage can achieve 80%+ efficiency, whereas wiki tells me that converting thermal to electricity with combined cycle gas turbines runs 64% https://en.wikipedia.org/wiki/Combined_cycle [wikipedia.org]
Considering that natgas (and nuclear) plants are already using turbines, maybe there is some opportunity to save money by converting existing equipment to use the hot blocks?
(Score: 2, Interesting) by engblom on Friday June 25 2021, @09:29AM (1 child)
I do not think you would achieve better efficiency by using gas to heat those blocks. When using electricity for heating the blocks, you have a very high efficiency as there are no exhausts, but when using gas for heating, a big percentage will go out with the exhausts.
(Score: 4, Interesting) by sjames on Friday June 25 2021, @06:00PM
The idea is to re-use the existing steam turbines on the output side and use electricity heating the blocks on the input side.
Another refit option might be to replace the boilers with solar heated thermal mass.
(Score: 3, Informative) by Immerman on Friday June 25 2021, @01:43PM (4 children)
Judging by their almost information-free teaser page, ETS is in fact looking to do exactly that:
It always irritates my sense of efficiency when electricity is used to generate heat though, considering that most electricity is currrently generated from heat, while throwing away roughly half the energy. And even solar cells capture well under half the available solar energy that strikes them. I suppose solar panels are a lot simpler than high-temperature solar-thermal capture systems though, and the electricity can be easily transferred over the grid from wherever it's generated to an electro-thermal storage system near new or existing turbines that can use the heat.
I suppose the thermophotovoltaics mentioned in the article might be cheaper and/or more convenient, but if they have only half the efficiency (30%) of a combined-cycle turbine that seems rather unimpressive. Who wants a battery that, even in ideal conditions, wastes 70% of the energy stored in it? Though I suppose I might be misunderstanding - it's not immediately clear what portion of that 70% escapes unused, versus being reflected back into the thermal battery.
(Score: 2, Informative) by Anonymous Coward on Friday June 25 2021, @02:25PM (1 child)
The big difference here is black body radiation - you know,radiation of hot things. A similar example are thermal panels vs. PV panels. The thermal panel will convert near 100% incoming into heat. The PV, well, you have that 15% or so. Automatically, you'd assume that thermal is a win-win -- cheaper and so much more efficient. For a 16m² installation, we were pulling about 15kW-thernal from the panels and into the house. BUT, as the temperature gradient increased so did the thermal loses. The 15kWt dropped to about 1Wt when the temperature difference were about 60-70C. So when the water temperature in the panels was 60-70C above ambient, they went to 0% efficiency. This efficiency is about linear with the difference. You may say, what's the big deal? The big deal is if you are trying to heat your hot water tank and the temperature outside is -30C -- suddenly it becomes stupid to try to heat it past +30C and you have to switch it then to start heating your house, not very efficiently either. PV cells, on the other hand, pull in for example 10kW in summer. In window at -30C, they can pull in 11kW at peak. See the difference? Consistency independent of the ambient temperature -- even better efficiency if the panels are cooled.
Agreed, this makes it not very useful. The only useful part of this setup is ability to store very cheap surplus energy from the spot market. But such conditions may not exist long enough to provide a return-on-investment.
(Score: 2) by Immerman on Friday June 25 2021, @03:25PM
That's heavily dependent on two factors:
1) how well your solar collectors are insulated from the ambient environment - only a relatively small fraction of solar energy is in the thermal-infrared range, and most of that gets diffused to uselessness by the atmosphere anyway. So, e.g. if your thermal collector is in a vacuum-insulated chamber with a solar collection window that prevents conductive losses and thermal IR from escaping, you can get a much larger thermal difference. At the very least if you want good solar gain you want the back and sides of your collector panel to be well insulated, with a double or triple-pane glass window (glass blocks most IR, and various coatings can improve things even further, unlike the much cheaper fiberglass or plastic windows often used for solar collectors)
2) the input solar energy intensity - most high-temperature solar-thermal power plants don't try to collect heat directly from ambient solar influx, instead they use large areas of relatively cheap mirrors to concentrate a whole lot of solar energy onto a relatively small collector, greatly increasing the temperatures that can be easily reached. Usually the collection is done with molten salts many 100s of degrees above ambient temperature. One of the simplest designs is stationary parabolic reflector troughs focusing incoming solar energy onto a pipe running along the focal "point", which can easily increasing the solar influx many dozens of times above ambient. Basically the same principle as using a relatively modest 1m Fresnel lens to melt steel, or even sand (~1700C) even without any thermal insulation at all.
(Score: 2, Interesting) by Anonymous Coward on Friday June 25 2021, @05:04PM (1 child)
I think you may be missing an important point of how energy storage will be deployed:
Overcapacity + Storage
When solar/wind is vastly cheaper to build than storage, before resorting to storage, you resort to overcapacity. You build enough capacity so that you still have plenty of energy at times of day that only have a little sun or wind, without resorting to storage. Not only does this mean that you need less overall storage, thus reducing cost, it also means that at other times of day, you have large surpluses of energy, with nothing productive to do with it other than storing it. This energy is essentially free. Storing it efficiently is not nearly as important as storing it cheaply.
(Score: 2) by Immerman on Saturday June 26 2021, @05:30PM
> This energy is essentially free
Umm...no. That energy is exactly what you're paying for by building far more generating capacity than would be needed with more efficient batteries. You only need that extra capacity because your batteries are so inefficient.
Now, all that extra overcapacity might still be cheaper than building more efficient batteries, so that the whole system still makes financial sense - but you have to compare the whole-system cost of the alternatives. Just looking at the batteries and saying "the extra energy is free" is deeply dishonest.
Now, there is one big benefit to thermal batteries if you're clever - they can do double-duty as supplementary fossil fuel plants to see you through the inevitable worst-case scenarios of extremely low renewable energy generation, rather than needing to build many times as many batteries to do the job, or needing to build, man, and maintained independent fossil fuel plants that are only used in such scenarios. Because so long as you need those independent plants to make up the shortfalls, their cost must be factored in to the true cost of the renewable energy sources.
(Score: 0) by Anonymous Coward on Friday June 25 2021, @04:21PM
I think just having the ability to store excess energy created by renewables is a huge win (for when there is not enough wind or sun, etc.) My personal favorite idea is to use that energy take synthetic gasoline/diesel and pull the carbon atoms from atmosperic CO2 to give us a way to nearly eliminate adding more CO2 from fossil sources and time to convert our existing cars and gas stations to whatever comes next.
(Score: 1, Insightful) by Anonymous Coward on Friday June 25 2021, @11:07AM (5 children)
But for those who prefer a simpler solution: nuclear. It's clean, green and too cheap to meter.
(Score: 4, Interesting) by Immerman on Friday June 25 2021, @03:38PM
Nuclear has the opposite problem - while wind and solar vary with no regard for demand, Nuclear *can't* vary fast enough to match demand.
My understanding is that a large plant can take several days to dramatically change its output (though admittedly many newer designs can vary significantly faster), meanwhile demand typically varies by a factor of roughly two over the course of any 24-hour period.
Even a fast-adjusting nuclear plant though can't handlte the instantaneous variations that fossil plants can - every time you turn a light on or off the power plant has to nearly instantly adjust its output to avoid sending the grid out of balance and creating all sorts of serious problems.
Of course, fast-adjusting nuclear + a battery buffer to handle instantaneous fluctuations could work just fine - but then you're back to needing lots of batteries... though not nearly so many as for solar, etc.
(Score: 2) by PinkyGigglebrain on Friday June 25 2021, @06:47PM (3 children)
Not sure if your being completely sarcastic but with the right reactor design and fuel chain nuclear energy can be safe, clean and a lot cheaper than many current sources of energy.
The points everyone always brings up in opposition to nuclear energy are always the same. Melt downs and long lived radioactive waste. Both of those are addressed by alternative designs. Molten Salt Reactors can't melt down, they don't use water for a coolant so there is minimal danger of radiation being released into the environment, and even if the core itself was damaged and the fuel leaked out it would stop fissioning and cool into a sold and relativly inert mass that would be easier to clean up, and wouldn't leach into the ground water. As to the waste issue, MSRs and other reactor designs can "burn up" their own waste as well as the waste already generated by the LWTR in use today. Reducing it to inert or very short lived radioactive elements. Additionally if the new reactors used Thorium as a fuel there is less waste generated in the first place, also Thorium is currently considered a waste product of rare Earth metal mining. The average Neodymium mine produces enough Thorium per year, as a "waste product", to provide the annual energy needs of the USA.
The bottom line is we need to be looking into every available Carbon neutral energy source we can find. Solar and Wind will not be able to meet Humanities growing energy needs indefinitely. And before anyone brings up Fusion consdier this, do you want to bet your, and your descendant's, futures on something that is "20 years away", and has been for the last 5 decades?
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 0) by Anonymous Coward on Saturday June 26 2021, @12:46PM
> The points everyone always brings up
You missed a big point. I always bring up greedy power plant owners, who cheap out on safety and maintenance in preference for profit. Let these jerks run a fossil fuel plant and they can cause local damage (fires, boiler explosions, that kind of thing). Let the same jerks run a nuke (of current designs) and they can ruin *much* larger areas.
(Score: 2) by HiThere on Saturday June 26 2021, @01:43PM
The problem with your answer is that it's interpreting promised technology as if it were in practical use.
Also, every nuclear reactor design I've seen also qualifies as a Rube Goldberg device, even without adding ANYTHING outside the basics. Like the ability to vary the power generation level quickly.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by Immerman on Saturday June 26 2021, @05:43PM
There is one issue with molten salt reactors - pretty much all of them use the molten salt to heat water through a heat exchanger in order to actually drive the turbines. And many (most?) of the salts used are highly corrosive, and react violently with water, so any failure in a poorly maintained heat exchanger that lets the water contact the salt is likely to result in a very violent flame-out. Especially for those reactor designs that actually incorporate the fuel into the salts, that would be extremely bad as if means you'll be venting a whole lot of highly radioactive combustion products into the atmosphere.
I really like MSR technology, but while they do eliminate a lot of specific failure modes of current-gen reactors, they also introduce new dangers if improperly managed and maintained - and the sad fact is that most historical reactor accidents have ultimately been because of improper management and maintenance.
(Score: 3, Interesting) by JoeMerchant on Friday June 25 2021, @12:36PM (3 children)
pump it up, extract energy on the way down. Bonus: fresh water storage.
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(Score: 1, Insightful) by Anonymous Coward on Friday June 25 2021, @12:53PM (2 children)
Something similar I saw was suspending massive weights in a mine shaft. When the wind is blowing or the sun is shining, use the energy to run a huge pulley system to raise the weight. When the wind stops or it's night time, reverse the pulley system to let the slow descent of the weight spin a turbine and generate power.
(Score: 0) by Anonymous Coward on Saturday June 26 2021, @12:49PM
> ... spin a turbine and generate power.
spin a generator directly.
ftfy
(Score: 0) by Anonymous Coward on Monday June 28 2021, @04:23PM
Are there any other kind? What would a weight without mass look like? </sarcasm>
(Score: 0) by Anonymous Coward on Friday June 25 2021, @05:39PM (3 children)
it think it's the same mentality of "oh hai let's find a coal mine and burn it for profit. the athmosphere and heat sink are free to dump to" and "oh hai let's wait with solar investment until we have a mine...err...storage for excess".
ofc the archilles heel of solar power IS intermittent source and storage and it seems everybody with a mine (or well) is gonna keep doing " a hector" (or "paris?)on it until it is solved (and they will prolly not help).
however small home solar installation can already help save alot of "one-time-through" original sources from depleting exponentially. but it seems a sudden collapse is deemed more desirable and profitable then a expanding out the time to collapse and maybe allowing a serious market for research and development to develop?
in short, you don't need to wait to (personally) invest in your own infinity energy plant until storage is solved ... it works right now (well at least when the sun is up).
(Score: 2) by PinkyGigglebrain on Friday June 25 2021, @07:00PM (2 children)
Nice concept except solar panels only have a useful life span of 20-30 years, after that their efficiency has dropped so much that you need to replace them. Also an issue is that they are not impervious to damage.
There is also that anoying little issue that not everyone has a roof of their own to put panels on. A 20 story apartment building only has so much roof space to try and power all of the apartments it contains. It's residents will need to supplement their electrical needs from an outside source.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 2) by Immerman on Saturday June 26 2021, @05:57PM
>Nice concept except solar panels only have a useful life span of 20-30 years
Depends on what you mean by "useful life" - most of the designs I've seen claim ~80% capacity after that period, and often do better than that, which is still extremely useful provided you have the room to install additional panels to make up for the reduced capacity (or initially over-provisioned with the eventual decay in mind). And even if you have to replace them in 20 years, the amortized cost can still be considerably cheaper than buying 20 years worth of electricity from the grid.
(Score: 0) by Anonymous Coward on Saturday June 26 2021, @08:09PM
it is true that land area is saved by "racking and stacking 'em".
however also true that a multi-story-multi-owner building has a roof.
it can be solved by, for example, declaring that total roof surface devided by number of unit owners is what each unit owner ...errr... owns of the roof.
thus if all in the block can agree or majority over vote or whatever to put a solar system on the roof then get a contract with the grid then connect it correctly (!) to the grid, with the output measured by ONE meter. this meter value of produced energy is devided by all units in the block (or the ones that agreed to solar and gave " their parcel of roof" to the project).
so, you have one monster meter from the grid and then smaller ones to each unit. INBETWEEN sits the meter from the collectif roof solar.
the value of "uploaded" electricity on the inbetween meter is devided by number of units (who gave their parcel of roof).
so now not each block unit gets a bill from.utility but only the monster meter from the grid.
from each smaller unit meter you can deduct your share of the inbetween meter.
ofc, if you are far away and nobody's home in your unit your reading will be negatif that is (maybe) some other people in you block will have to give you money. it is solved internally.
the grid operator will probably still get to collect moneys according to their main monster meter but hopefully ALOT LESS!
and that's how you do blocks ...