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Comment by mabbo | Hacker News Reader

Interesting: CO2 gets pressurized, cooled to liquid temperatures via refrigeration, then uncompressed to spin a turbine when energy is needed.

Concerning:

> The engineer explains that Energy Dome does not want to build projects itself.

> “We don’t have the capability to grow as fast as the market requires,” he says. “So our model is to license the technology to EPC companies or IPPs, utilities, the final user, because that is the best way for us to expand geographically and by sector.

They are so confident in the economics of this tech that they'd rather someone else invest in it. How generous and not at all suspicious.

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> They are so confident in the economics of this tech that they'd rather someone else invest in it. How generous and not at all suspicious.

This is not an entirely uncommon business model, and there are numerous examples of the developers of a technology licensing it for production and distribution. ARM is itself one example of this.

https://en.wikipedia.org/wiki/Arm_Ltd.#Business_model

It is entirely valid for a technology inventor to commercialize their invention by partnering with a manufacturer that already has the necessary production capacity, rather than by raising outside money to scale up their company and build new production capacity. The former can often be a lower-risk, higher-reward approach compared to the latter.

The real question is whether the technology actually works. If they can prove it works, the fact that they would license this technology to third parties for manufacturing and distribution is not itself suspicious at all.

> They are so confident in the economics of this tech that they'd rather someone else invest in it. How generous and not at all suspicious.

I mean, I think this is pretty standard in highly capital intensive industries?

This is common in the electric utility industry where scaled up tech costs 7-9 figures per unit or more.

> Interesting: CO2 gets pressurized, cooled to liquid temperatures via refrigeration, then uncompressed to spin a turbine when energy is needed.

Can someone explain the maximum theoretical efficiency of this process from basic thermodynamic principles?

Carnot cycle, isn't it? Not great for efficiency, probably less than 50% round trip.

Carnot is for heat engines. So the maximum efficiency of converting a heat differential into kinetic energy.

This is converting electricity into kinetic energy and vice versa. So it'd be the product of those two maximum efficiencies, whatever they are.

> This is converting electricity into kinetic energy and vice versa.

Where do you get that from? The article definitely seems to me to be describing a heat engine.

Basic thermodynamics doesn't prevent you from cooling something reversibly.

That said plenty of the steps involved here are likely not 100% efficient, and I'm somewhat unsure where they're recovering the energy involved in the gas-liquid phase-transition, if at all.

The whole article is leaning a little bit too much on the "what if"-part of things. First it will be important to see whether their first at-scale Prototype actually works next year.

Honestly I don't see why it wouldn't work. All the steps of the process seem like old and proven technology to me. Perhaps the only innovation is this "elastic" CO2 storage for ambient temperature/pressure ?

However, the key information will be performance numbers actually coming out of it

> cooled to liquid temperatures via refrigeration

Do you actually need to refrigerate it to keep it liquid? My SodaStream machine works with room temperature.

"It can only exist at a pressure above 5.1 atm (5.2 bar; 75 psi), under 31.1 °C (88.0 °F)" - https://en.wikipedia.org/wiki/Liquid_carbon_dioxide

So depending where you are you'd need refrigeration

It doesnt need refrigeration for storage, CO2 is stored at higher pressure

The refrigeration is needed because the process of compression produced huge amount of heat. And because of that, this method of storing energy is twice less efficient than batteries are

Though they could store some of this heat for later when they want to extract the CO2 gas again, I suppose.

Which according to the article is what’s happening. They store heat in steal piles, and release it back on expansion.

Charging batteries also produces a huge amount of heat. In general, storing energy is never free. It's the tyranny of the second law of thermodynamics.

Yes, the critical point for condensation of CO2 is 31 C:

https://courses.lumenlearning.com/physics/chapter/13-5-phase...

However, I imagine you could wait for your too-hot-to-condense gas to cool and condense. That would probably be vastly more efficient than adding refrigeration.

It would depend on the materials used for the pressure tank, whether you can add more surface area and the external temperature.

You could even put the CO2 Tank under water in a deep lake/ocean. Then you don't have to have such thick materials to contain the pressure. The CO2 could be dissipating its heat and pressurizing as you pump it down (use a flexible tube so the water is compressing the CO2). For the return journey, use a rigid pipe so it doesn't lose energy pushing outward on a flexible pipe.

My understanding is that the energy released comes from the CO2 being heated back up and turning into a gas, causing it to expand. This spins turbines.

Sodastream doesn’t use liquid CO2, just compressed gas.

Demonstrably not true. In fact you can refill your Sodastream canister with dry ice, google it. 400 grams of it sure as heck doesn't stay solid and I'm pretty sure it can't be gas at that pressure in that amount of space.

EDIT: https://en.wikipedia.org/wiki/Supercritical_carbon_dioxide, you can't slosh it.

https://www.youtube.com/watch?v=GEr3NxsPTOA

It looks like you’re right. Whoops.

There's nothing usual about that. Lots of technologies get licensed.

Is it defensible (patents etc)? If it's easy to copy then it would be best to partner with those who need to invest the least to get this to market.

imagine a world where your inexperienced take gets amplified unceremoniously

and here we are

Such confidence. Will make…. Unprecedented…. 5bere would be so many ideas that have not scaled, run into technical problems, ……. Would be nice if they had data from a pilot plant that was representative

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