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Comment by danw1979 | Hacker News Reader

danw1979

I was going to point out how crazy it is to even suggest that we'd install 10 times the total electrical generating capacity of mankind, in the form of imaginary reactor technology, just to scrub our existing CO2 emissions, but I think that might be the point...

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Electricity generation is pretty cheap and doing it 10x more wouldn't be too hard. In fact if it fixed our CO2 problem, it would be an oustanding deal.

I suspect the grandparent was hinting that if we went ahead and generated 10x more electrical energy than now, we'd use it to just stop using fossil fuels entirely, rather than keep using fossil fuels and then pulling that CO2 back out of the atmosphere.

You can't stop using fossil fuels for everything just yet. Rockets, planes, still need fuels with high energy density - they won't run on batteries (at least with the current technology). There are of course other industries where fossil fuels are currently the basis for chemical reactions as well.

Hydrogen from hydrolysis seems like it might work, if you are willing to replace the current fleet of vehicles.

We can make hydrocarbon fuels too. Eg Fischer–Tropsch, https://en.m.wikipedia.org/wiki/E-diesel etc.

Hydrogen is more efficient though.

Yes, but hydrogen is just a bad battery.

It's awkward and relatively unsafe to handle, and has low energy density.

You'd be better off making eg synthetic petrol.

Those two are a very small portion of total emissions.

But there is power to fuel, and I think the main problem with power-to-fuel is energy consumption of the process.

From https://www.sciencedirect.com/science/article/pii/S096014811... it looks like input electricity cost is around half of the costs and efficiency is around 50%. If electricity is abundant then this is still ok.

You can make synthetic plane fuel, whose burning just releases the same carbon captured when made.

(I don't know enough about rocket fuel.)

Of course, making that plane fuel will cost energy. But probably closer to eg 2-3x the energy regained on burning than 10x.

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