Energy Dome’s approach to long-duration energy storage

Summary:<p>&gt; Energy Dome’s novel approach to long-duration energy storage dispenses with batteries altogether. Instead, the company erects enclosures that resemble tennis bubbles and fills them with carbon dioxide gas. Excess electricity can be used to pressurize the gas into liquid form, storing energy; turning the liquid back into a gas releases that energy, turning a turbine and regenerating electricity.<p>&gt; As detailed in Canary Media’s previous reporting, this approach has a few advantages relative to other long-duration storage attempts:<p>&gt; It uses off-the-shelf equipment from mature industrial supply chains. That means Energy Dome doesn’t need to build its own factory, a capital-intensive step that other long-duration startups needed to do. It also means Energy Dome doesn’t need to spend years on laboratory science — it just needs to prove that the equipment all works together the way it’s supposed to.<p>&gt; The dome is supposed to deliver round-trip efficiency of 75 percent, meaning 75 percent of the energy that goes into the process comes back out at the end. That’s less than typical battery efficiency but a lot better than many long-duration storage contenders.<p>&gt; Carbon dioxide is easier to compress and store at ambient temperature and atmospheric pressure compared to other gaseous storage vehicles, like hydrogen or air.

sorry to disappoint, but this article glosses over a pretty significant constraint that prevents this from being long-term storage at all: storing the thermal energy from the compression process.<p>storing thermal energy over long periods of time is a pretty lossy process, and that 75% efficiency number will be out the window if one tried to use this system for seasonal storage. this system fills the same space as battery storage, which it is also marketed for (over night storage for solar power).<p>here is a more detailed post on the matter: <a href="https:&#x2F;&#x2F;www.rechargenews.com&#x2F;energy-transition&#x2F;new-co2-battery-will-make-wind-and-solar-dispatchable-at-an-unprecedented-low-price&#x2F;2-1-1044755" rel="nofollow">https:&#x2F;&#x2F;www.rechargenews.com&#x2F;energy-transition&#x2F;new-co2-batte...</a><p>citing from this: &quot;In Energy Dome’s system, carbon dioxide is compressed at a pressure of 60 bar which heats the gas to 300°C liquid. The heat is then extracted and stored in “bricks” made of steel shot and quartzite for later use, cooling down the CO2 to an ambient temperature. The gas is then condensed into liquid form and stored in carbon-steel tanks.<p>‘Our lithium-ion battery will have double the energy density of standard Li-ion for same price’<p>When electricity is required, the liquid CO2 is run through an evaporator to turn it back to a pressurised gas, which is then warmed up back to 290-300°C causing the stored heat.&quot;

I wish they had data on the estimated cost to build and operate. Best i can guess is that $11M might get them 200Megawatt&#x2F;hours -&gt; $0.055 per watt hour which would be cheaper than any chemical battery based energy storage, albeit at the cost of reduced efficiency (75% vs 95% for lithium-ion). This is similar to pump storage, but less geographically dependent.

Isn’t this setup a giant BLEVE-bomb? Where will these be built? Shouldn’t they be buried rather than surface domes? <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Boiling_liquid_expanding_vapor_explosion" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Boiling_liquid_expanding_vapor...</a>

It&#x27;s not perfect, it it&#x27;s not a scam, and has a reasonable round-trip efficiency at scale big enough to be useful. This will be helpful in our transition away from liquid fossil fuels.

What happens if the dome ruptures and suddenly releases all its CO2 into the surrounding air? Will it hang around long enough to be dangerous for people (or other living things which like to breathe). Given that they&#x27;re cycling between gaseous and liquid states, there&#x27;s presumably quite a bit of CO2 involved.

Neat. It&#x27;s like a hydraulic hybrid for the grid.<p>Hydraulic hybrid vehicles recapture 75% to 80% of braking energy for reuse, which compares very favorably to electric batteries.<p>Something like this paired with intermittent sources like solar and wind could make them viable.

75% is an awfully round number for efficiency!

Anyone know of a reason why they dont use air? or even Nitrogen.<p>EDIT I guess compressing to liquid, CO2 can be stable at &lt;31 deg C at 5ATMs which is what they use. Liquid Nitrogen has to be kept very cold, even under pressure.

That makes me chuckle that they use CO2.<p>It would look like a good idea only if they somehow compel their customers to buy only CO2 coming from a direct-air-capture facility.<p>Or even better, if they attach a small direct-air-capture device to their &quot;bubble&quot;. (it would not need to be extremely efficient, as I understand that the CO2 is then captive of the storage [I&#x27;d add... <i>in a normal operation mode</i>... because we never know what can happen with incidents and that&#x27;s why I push for DAC before it&#x27;s too late and it&#x27;s already everywhere])

The nice thing about this is that it requires nothing even as exotic as batteries. It seems like you can build it out of off the shelf stuff.

10 hours of discharge time (20 MW power peak with 200MWh energy storage) is good, but not &quot;long term&quot; to me. It is barely sufficient for storing solar&#x2F;wind overnight. &quot;Long term energy storage&quot; to me is several days or more at peak power. I&#x27;m excited for all these different methods, though, because unlocking energy storage is key to reducing carbon emissions, since most of the base load is from carbon emitting power sources.<p>Edit: I clarified that I meant the <i>amount of energy stored</i> not how long the gasses themselves can be stored. &quot;Long term energy storage&quot;, to me, should be defined as being able to discharge at max power for like a day or more, and this tech is more &quot;medium term&quot; storage, again in my opinion.

Is this any more effective than just pumping water into a higher reservior? It seems like a lot of stuff can fail here.

No such type of idea will ever work.<p>Because by definition, any long term storage solution will be able to sell energy and make a profit only a few number of times, and won&#x27;t be able to recoup its CAPEX expenditure.<p>Let&#x27;s say that by long term you mean 6 months (the typical period envisioned, i.e. you charge during the Summer months, and sell during the Winter months). Then you&#x27;ll be able to sell energy once a year. If your system has a lifetime of 20 years, then you need the CAPEX to be only 20 times higher than the annual profit.<p>Let&#x27;s further say you charge during Summer at zero cost, and sell during Winter at 40 cents&#x2F;kWh (this is about 3 times the average cost of electricity in the US for 2021). Then the cost of this system should not be more than $8&#x2F;kWh. For comparison the cost of a Tesla Powerpack is about $700 &#x2F;kWh [1].<p>So for any system to have any hope to be &quot;long term storage solution&quot; it needs to be 100 times cheaper than the Tesla Powerpack.<p>In reality it needs to be about 1000 times cheaper, due to numerous other factors: less than 100% round-trip efficiency, the high cost of financing (driven by the significant risk of the project, which is driven by the huge uncertainty regarding future potential competing technologies, such as Hydrogen), operating and insurance costs, etc.<p>There is a way to solve the long term storage system. You need to solve the apparent paradox that if your system is designed to be long term, then you can&#x27;t buy and sell very frequently. Here&#x27;s how you solve it: you buy and sell in different markets. You buy (solar) electricity in Morocco pretty much all year long, convert it to Hydrogen, or some other form of chemical storage (ammonia, hydrogen peroxide, methanol, synfuel), and ship that to Germany, where it is converted to electricity, again all year long.<p>This way, you buy every single day and sell every single day. You are able to recoup your CAPEX costs, and make a handsome profit.<p>There are no other ways to solve the long term storage problem.<p>The EU knows that, and this is why it is betting so heavily on Hydrogen.<p>[1] <a href="https:&#x2F;&#x2F;electrek.co&#x2F;2020&#x2F;03&#x2F;31&#x2F;tesla-powerpack-price-commercial-solar&#x2F;" rel="nofollow">https:&#x2F;&#x2F;electrek.co&#x2F;2020&#x2F;03&#x2F;31&#x2F;tesla-powerpack-price-commerc...</a>

Just curious. How much liquid CO2 will be required for storing the energy mentioned in the article?

&quot;It was designed according to ancient ziggurat mound proportions used in votive worship. Like the mounds it collects energy and recirculates it. In this case the Dome collects the Orgone energy that escapes from the crown of the human head and pushes it back into the Medulla Oblongata for increased mental energy. It&#x27;s very important that you use the foam insert...or better yet, get a plastic hardhat liner, adjust it to your head size and affix it with duct tape or Super Glue to the inside of the Dome. This allows the Dome to &quot;float&quot; just above the cranium and thus do its job. Unfortunately, sans foam insert or hardhat liner, the recirculation of energy WILL NOT occur.&quot;