Comment by s1512783 | Hacker News Reader

Comment by s1512783 | Hacker News Reader

Here's what I don't understand - You're taking CO2 out of the atmosphere using renewable energy sources. Thermodynamically, this will take at least as much energy as it took to burn them. You did not mention how energy efficient your energy storage method is right now (50-60% at maturity sounds really optimistic, when plants are only a few %), but, in the short term, while we're still mostly using carbon-based fuels, you're basically diverting renewable energy capacity from consumers. Instead of getting 1kWh of usable energy from a solar panel, they're getting at best 0.5kWh, albeit in a much denser form that's easier to move around for some transportation uses, such as aviation. But, in the short term, you have a net-negative impact.

In the long term, if things keep going where they are going and we end up having to remove carbon from the atmosphere to reverse some effects of global warming, why would we want to convert it into gasoline instead of e.g. just capturing it and storing?

Or is this just a way to generate jet fuel for planes of the future when we'll electrify all of transportation except for flying?

Demonstrated overall conversion efficiencies for CO2 to fuels are already in the 25-50% range, depending on the fuel. We are confident we can get to at least 50% for our process. We will not be taking renewable power away from other uses - in the short term we'll be using marginally useful power (wind at midnight, solar at noon, etc), as we need the power to be low cost, and any time it has higher value uses, it won't be cheap enough. So we are not removing it from other beneficial use. Also, as we scale, we will cause much more solar and wind power to be available as we will be buying a lot of it. In the long term, aviation and shipping are likely to still use liquid fuel, yes.

Thanks for the reply, I get the load balancing part now, I did not think about that.

I was thinking a lot recently about flying and how we could make it work in the (hopefully) greener future. This is definitely a more sensible way of doing it than electric jets, good luck with your company!

Thanks!

How do the unit economics look for using your tech as a battery store and then burning excess fuel for grid energy when demand is high?

One cool thing is that one could build huge power plants in the middle of nowhere, and not worry as much about transmission losses. Oil fields are already typically in the middle of nowhere, and fuel travels and stores easily.

Look at it from an economics standpoint... because of the efficiency loss, energy from this process would always be twice as expensive (or more) than freshly generated renewable electricity. So you'd only want to use it in places where grid electricity is impractical.

Vehicles are the obvious market. It took over a century for electric vehicles to become even remotely practical. But vehicles are necessarily disconnected from the grid.

And even for vehicles, this is only desirable when consumption needs or disconnect times are very high, like aircraft and oceangoing ships. That's because combustion is very wasteful. There are about 33.7 kwh of energy in a gallon of gasoline. A Tesla goes as far on three gallons' worth of energy as a comparable Mercedes goes in ten or more. That's because an electric drivetrain is 3x (or more) more efficient than a combustion one.

So using this process, it could cost 10x as much to operate a fuel-based vehicle as an electric one. You don't want to do that unless you have no other choice.

Probably just the last line? Even still, we can easily build out way more solar than we need so if there remains a need for energy dense carbon fuels then why not?

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