Hydrostor is re-envisioning compressed air storage

Hydrostor is re-envisioning compressed air storage
Hydrostor Advanced Compressed Air Energy Storage (A-CAES) demonstration facility, Toronto, Ontario. Credit: CNW Group/Hydrostor Inc.

(Tech Xplore)—Canada-based Hydrostor on Wednesday announced Hydrostor Terra, a bulk energy storage system. The company says the system competes head-to-head with new natural gas plants.

The head of the company stated, "Battery technologies can't compete with new , but Terra does. The value proposition for utilities is compelling, and for us that's translating into projects."

This is about creating caverns on demand. The Hydrostor Terra system involves an isobaric underground cavern for air storage. It can be deployed at any site near a body of water. That includes inner-city and urban areas.

Greentech Media explained. The company digs what look like mine shafts customized to the needs of a given project. "The team installs silencers on the vents to cut out noise pollution."

The company says the result is bulk energy storage at half the cost of competing technologies. They call the bulk energy storage technology Advanced Compressed Air Energy Storage, or A-CAES.

But first back to CAES. Prachi Patel in IEEE Spectrum turned to the fundamentals of CAES: "Such systems use off-peak electricity to run compressors and store the compressed air, which can later be expanded to drive a turbine." Only one problem—conventional CAES costs. Patel said it needs underground geological formations to store the air and it is expensive.

Greentech Media's Julian Spector also said, "Traditional CAES seals air inside pressurized salt caverns. So to build one, you have to go find a cavern big enough for your needs and strong enough to withstand the pressure without leaking."

This one uses utilizes hydrostatic pressure from a water-filled shaft to maintain a constant-pressure system during charge and discharge, which reduces the cavern size required as compared to traditional CAES systems.

(Patel said the underground cavern was built to operate at low and constant pressure. "The cavern has to be connected to a local water body via a pipe so that water can enter and leave the cavern as air goes out and in. The water in the shaft and cavity helps keep the air under constant pressure.")

"When charging," said the video notes, "compressed air is piped from the surface into the purpose-built accumulator, displacing water up the shaft and back to its source. Conversely, when the system discharges, compressed air flows back up to the mechanical equipment while gravity forces water to flow into the accumulator, displacing the air."

Who gains? The company said utilities and electricity system operators can cost-effectively and reliably address the issues of reserve capacity, peak shaving, transmission congestion and renewables integration.

Hydrostor is re-envisioning compressed air storage
How Hydrostor Advanced Compressed Air Energy Storage (A-CAES) works . Credit: CNW Group/Hydrostor Inc.

On the topic of cost, the company said this would enable "the transition away from fossil-fuel generation at half the cost of competing ."

Moving forward, Curtis VanWalleghem, President and CEO of Hydrostor, said, "We are engaged with several utilities around the world to deploy systems rated at hundreds of megawatts, delivering gigawatt-hours of at durations ranging from four hours up to multiple days."

According to Spector, "The Terra solution is highly customizable and allows customers to pick the power-to-energy ratio. For systems of 200 megawatts or more, VanWalleghem said, Hydrostor can deliver 6 to 8 hours of duration on a turnkey installed basis of $150 per kilowatt-hour."

IEEE Spectrum discussed the Hydrostor concept of building underground caverns as an affordable approach in Compressed-Air Energy Storage.

Prachi Patel: "The case for storing large quantities of electrical energy is getting stronger and stronger, whether to expand the use of solar and wind power or to meet surges in demand on the grid."


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Apr 14, 2017
This press release is mumbo jumbo. Batteries and CAES don't compete with natural gas plants, because gas is a fuel obtainable already "charged", not just storage. Underground CAES competes with batteries and with pumped water power storage. Indeed this product is a hybrid of pumped air and water.

There's no mention of the roundtrip charge/discharge efficiency, or other operating efficiencies (losses) and costs.

Also, at $150:KWh A-CAES is expensive to build: At about $0.04:KWh average US retail (excluding network delivery charges), the storage would have to operate continuously for over 15 months just to break even. Of course the unmentioned inefficiencies and costs would make that even longer, maybe over 2 years. And of course it's going to operate at most half the time (if storing solar for overnight discharge), so getting to 7 or more years. That's not the kind of ROI utilities invest in.

How about a science report instead of an advertisement?

Apr 14, 2017
What is the ROI of a nuclear plant?

Will it actually produce more energy than it took to build it?

The government stopped the research company for which I worked from finding out, by threatening us with no more government work if we did it.

Apr 14, 2017
"Also, at $150:KWh A-CAES is expensive to build: At about $0.04:KWh average US retail (excluding network delivery charges), the storage would have to operate continuously for over 15 months just to break even."

That is not exactly true. You could buy the power during production spikes when power is very cheap and resell it during peak hours when it is expensive. The feasibility of the system just comes down to cost and the total round trip efficiency. Also, the system, once built, should be able to operate for many decades without degradation. Batteries, on the other hand, have a very limited lifespan.

Apr 14, 2017
Indeed the entire point of storage is to "buy [energy] low, sell high". Without knowing the many actual inefficiencies and operating costs (not mentioned in the article), who knows how large a spread is needed for the ROI to compete with other investment by the utilities. That's why I complained about lack of science.

The pumps and other mechanics are going to require maintenance, and a new tech is going to have other unknown costs.

A vanadium liquid electrolytic (V-Flow) battery tech that is just arriving is claimed by Forbes to cost $0.05:KWh :
https://www.forbe...bb8e5bde

Lazard states costs even lower per KWh (converted from per MWh):
https://www.lazar...#page=10

Actual details are necessary to see where "Hydrostor" fits.

MR166:
That is not exactly true. [...]


Apr 15, 2017
Well the bottom line is that wind and solar will not reach their full potential until we have a way to store energy and match the supply with the demand.

Apr 15, 2017
I agree. Their full potential is complete supply of human power consumption. Storage is essential to getting to even close to that potential, flipping from exceptional to baseline. And at prices dropping from Lazard's 2015 list, we are getting close to that.

That's why it's time for science reporting, not press releases. The public has to understand the real choices, not just the marketing.

MR166:
Well the bottom line


Apr 15, 2017
"Indeed the entire point of storage is to "buy [energy] low, sell high"."


Here's the thing though. The unsubsidized cost of e.g. wind power is in the $50-70 per MWh while natural gas comes in at $45/MWh. The only reason you can buy renewable energy surplus on the cheap is because it's subsidized, so the producers can pull off even negative prices to collect the subsidy.

The subsidies can't continue forever: at some point the producers have to start making their own ends meet. When that happens, they can't sell you the power at zero cents a kWh anymore. The turbine owners have to start asking the full 5-7 cents for all the power, or go out of business.

So when the base price is already that high, the economics just isn't there, because the times when the electricity prices hit high enough to make profit aren't very many hours in a year.


Apr 15, 2017
The system is basically a reverse version of pumped hydro storage. It's principally identical to just digging a deep hole and dropping water through a turbine into it: add pressure at the bottom and it lifts the water out, release the pressure and the water falls in.

It has the same basic problem: all the energy comes from the weight of the water - lots and lots of water. You need to empty and fill whole lakes of water to get gigawatt-hour scale storage, which creates geological and biological problems, namely earthquakes, soil erosion, and methane emissions as the water levels fluctuate.

For example, a 1 sq-km 2 meter deep lake contains 2 million tons of water. Drop all that water by 50 meters down several mineshafts, and you got 0.275 GWh of energy. That's not a whole lot. For the 200 MW plant, it would be just 1 hour 20 minutes.

And it's a whole lot of work to dig those mineshafts, because the total volume must equal that of the lake.

Apr 15, 2017
All energy systems in the US (as elsewhere) are subsidized. Natgas has been subsidized for well over a century, an investment that results in a highly competitive component of the US energy system. Petrofuel subsidies persist as a significant component of their large profits (and even more of their risk mitigation), though they're not necessary These subsidies aren't going away.

Subsidies for wind and solar are more vulnerable because of political disadvantages vs the competition, and more necessary because these renewables haven't had the investment (including subsidies) to scale to stability like their competition.

Eikka:
Here's the thing though


Apr 15, 2017
Pumped hydro doesn't have to use mine shafts. For example a hydroelectric dam can discharge its storage normally when the grid needs power, then pump water back up when the grid has excess power (sunny/windy day) to recharge the storage. If necessary the dam can have long recharge intakes from downstream to reach water that flowed to lower elevations. Or else a second dam downstream to keep the water recoverable. New reservoirs with better geography/topology for the purpose are feasible, regardless of upstream inflow.

It's a lot of work but it's worth it, and very low risk when engineered right. Compared to say building and operating a giant arctic oil fracking platform, even in just the blowout potential, which is well worth its very high cost to petrofuel corps working on them right now.

Eikka:
The system is basically


Apr 15, 2017
"All energy systems in the US (as elsewhere) are subsidized."


None to the same extent per kWh, and bar some individual exceptions, none are subsidized per kWh like wind and solar, to the point where the government is directly buying every kWh with taxpayer money.

The utilities find the power very low value because of its intermittency, because adjusting to the variation costs them money, and the wind power PPAs go as low as 2.5 cents a kWh. Whatever spills over from the predicted day-ahead market is sold on the spot market for even less - yet this is profitable because the government is paying 3.5 cents average for every kWh they manage to sell and the states add their own subsidies.

If wind producers couldn't have this subsidy, their cost would be around 5 cents a kWh, but the price they'd get on the market would be around 2-3 cents because the utilities don't want random power.

The ends just don't meet, so wind energy remains on life support by subsidy.

Apr 15, 2017
Now, the point of it: if they're claiming to sell electricity on par with natural gas powerplants, they first have to buy the power. They see renewable energy on the grid selling for 2-3 cents, add in costs and inefficiencies, and come out with 4-5 cents which is on par with natural gas - but this is not a honest comparison because it depends on the continued subsidy on the renewables which is becoming impossible to maintain.

The real cost is elsewhere, paid by "someone else". The real cost to the consumer is greater than advertised.


Apr 15, 2017
I don't know that oil and gas aren't subsidized as much or more than solar and wind. Where are the actual numbers to compare? It doesn't matter whether the basis is to the consumer per KWh, or $billions annually to USGS and many other Federal/state/municpial/county government agencies, including the cleanup costs, or eminent domain handovers of land, or rockbottom leases for extraction, or public R&D budgets, or taxpaid costs of litigation, and on and on. How do we account the subsidy of the Iraq War, which supported oil up to over $150 per barrel for years? For the subsidies of the first century and more to oil and gas, that included the purchase of Alaska, the extermination and removal of whole nations from Texas/Oklahoma/etc.

And even solar and wind were more subsidized, so what? Nobody questioned the subsidies until they were competing with the (still subsidized) oil, gas and nukes. Subsidizing energy is the American way.

Eikka:
None to the same extent per kWh

Apr 15, 2017
The consumer doesn't pay the storage costs, the grid operators do. The probably too-low stated prices of this storage are to con investors, the industry, and probably government regulators.

I agree that these storage systems aren't competing with natural gas because they're not energy sources, their costs are atop the costs of whatever energy source they're improving by matching supply times better to demand times.

Eikka:
Now, the point of it


Apr 15, 2017
"The consumer doesn't pay the storage costs, the grid operators do."


Who then charge the consumers for the cost. They're not a charity you know.

" Where are the actual numbers to compare?"


The EIA has the numbers:
https://www.eia.g...subsidy/

Of course you need to do a bit of math to get the per unit energy figures out, because it would be too obvious for the government to just tell you directly, but it comes out at $35.1 per MWh and for solar it's a whopping $235/MWh. The situation hasn't changed since 2013, and won't be changing any time soon even if Trump calls a halt to new subsidies, because the old ones still apply to the existing powerplants and new ones won't be built without the subsidy.

All the others, gas, coal, nukes get less than $2 per MWh.

Apr 15, 2017
"I don't know that oil and gas aren't subsidized as much or more than solar and wind. Where are the actual numbers to compare?"

You can look here. Off shore(!) wind is already being built without subsidies.
https://www.nytim...tml?_r=0

We have been waiting for coal, oil, nuclear and gas to go without subsidies for more than a century. They haven't managed that yet.

Game over.

Apr 15, 2017
From the report: "the scope of the present report is limited to direct federal financial interventions and subsidies that are provided by the federal government, provide a financial benefit with an identifiable federal budget impact, and are specifically targeted at energy markets"

Not included are the many subsidies built into the US industrial system that are not direct cash from a Federal budget to an energy corp. As I mentioned, the USGS and plenty of other R&D, favorable land handouts. Then there are the indirect subsidies to US industry that for example favor internal combustion engines, fertilizer and pesticides all of which consume petrofuels. The US Navy patrolling the world's oil and gas tankers is yet another. I mentioned the Iraq War, the list of wars for oil is as long as the history of the industry. Over a century of US industrial policy has woven these subsidies into the entire system, for well over a century.

Eikka:
The EIA has the numbers:

Apr 15, 2017
Yes, but as I said it's not the consumers who are the marks for hype about storage, it's the grid operators. No consumers are persuaded to spend more by storage hype, and it's not their decision anyway as prices are almost all tariffed by regulators. The grid operators and their regulators are the targets for the hype.

Eikka:
Who then charge the consumers


Apr 15, 2017
Let's not forget that wind power systems, and solar even more, have been subsidized by taxpayers - think NASA. Even if sustainable power systems cease using subsidies there's decades already invested that will take decades to pay down as lowered costs, avoided costs from damage (health, environment, foreign entanglements) and new development (solar especially has spinoff tech) all accumulate their returns in taxes and economic growth. And let's not forget how much petrofuel energy has been invested in developing and delivering sustainable energy tech.

Energy is so fundamental to a global industrial hub like the US that real perspective is going to be more complex than any simple analysis. The American people have always invested money through our government, as have other countries. That is a reasonable way to operate a tech society, and it's been an unparalleled success. Especially when it's grown out of buggy whips.

antialias_physorg:
You can look here.


Apr 16, 2017
" Even if sustainable power systems cease using subsidies there's decades already invested"

So? They are now viable without subsidies, while ALL the old power sources aren't. You tell me which is better: paying once and then never again - or keep paying forever?

Seems like a no-brainer to me (and we're not even talking waste disposal, energy security, international conflicts due to concentration and competition over resources, climate change, and public health...any ONE of which would make renewables with massive continuing subsidies a win-win)

Apr 16, 2017
I agree with you. I just don't think subsidies are all bad. I think subsidizing industries that are both independently profitable and costly in their downsides is bad.

Though that NYT article does point out that the (directly) unsubsidized Danish offshore wind bid will work only if electric prices rise and equipment costs fall by 2024 as the winning bid discloses it depends upon. But that just means offshore wind is, in at least some cases, "within reach" of deployment without direct subsidies. Increased efficiencies are a fairly safe bet. Which means that by 2030 or so electricity costs below 2017's without direct subsidies are probable.

antialias_physorg:
So?


Apr 16, 2017
This will not help mobile vehicles, though! Drones should keep track of charge of battery of ALL Vehicles on the Road. We have GPS. Similary, Some system should be there where DRONES will Arrive, Push in a Charged Battery, Pull out the Discharged Battery and Fly Away....All While The Vehicle is in Motion! So, There should be Drone Stations on either side of the highways/roads.

Apr 16, 2017
" I think subsidizing industries that are both independently profitable and costly in their downsides is bad."

Not sure what you're trying to say here. How can a subsidized industry be profitable? If it's profitable it doesn't need subsidies.
What I'm saying is that renewables have become far more quickly able to do without subsidies than nuclear, coal, oil or gas. None of which would be viable without subsidies today.

Apr 16, 2017
This is the type of tech I was talking about that makes local microgrids possible. The next shift in thinking is to where centralised power generation is only a small part of the energy distribution system. Subsidies and taxes also become less relevant.

Apr 16, 2017
I know what you're saying, and as I said I agree with you. Oil, gas, nukes are subsidized industries that are profitable. I don't think subsidies are right for them, especially since it's subsidizing much larger costs in the harm that operating them causes.

antialias_physorg:
How can a subsidized industry be profitable? If it's profitable it doesn't need subsidies.


Apr 16, 2017
What is the ROI of a nuclear plant?

Will it actually produce more energy than it took to build it?

The government stopped the research company for which I worked from finding out, by threatening us with no more government work if we did it.


Obama's government?

Apr 16, 2017
The thing is that they aren't profitable. What do you think nations (especially the US) have military expenditure for? To secure these power sources. (No, the US is not under threat of invasion - never has been)

Factor that cost in and there's no profit in the old energy sources overall.
(Of course there is profit for the owners of power companies while the costs of the subsidies and the military is shouldered by the taxpayer. Privatize profits - socialise costs. In other words: the whole thing is a kleptocratic scam. That's why some governments are so reticent to switch over. They'd lose the reason for shoveling all that money from taxpayers into private pockets. Probably have to find a new way like starting a war or two.)

"What is the ROI of a nuclear plant? "
Including a million years of waste disposal? Take a wild guess...

Apr 16, 2017
Well, they are profitable, though the subsidies keep them that way. Here's 2014 US/Canada oil/gas profits of $257B, also mentioning the tens of $billions in direct subsidies that result in those profits:
http://priceofoil...-canada/

I don't think anyone can say what the profits would be without the subsidies. Really, the cost of clearing whole nations from lands exploited for oil, Iraq War, so many wars for oil - Vietnam for the offshore gas fields, all General Snidely Butler's "War is a Racket" wars. But the simple fact is that the companies return profits to their shareholders, atop salaries to their workers, payments to vendors and reinvestment budgets, even as they receive large direct cash subsidies. Those cash subsidies are absurd in the face of profits. The indirect subsidies are also wrong, but are distinct.

antialias_physorg:
The thing is that they aren't profitable.

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