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Comment by nickcw | Hacker News Reader

Let me get out my back of the envelope for some quick and inaccurate calculations ;-)

There are 10.3 kWh of energy in a litre of Jet A1 fuel.

Let's assume (generously I think) that the process is about 50% efficient, so it takes ~20 kWh of electricity to make a litre of Jet fuel.

Assuming (amortized) solar power is the same cost as grid power ~$0.1/kWh then to make your litre of fuel costs 20 *0.2 = ~$2/litre

According to my research Jet A1 costs about ~$0.50/litre.

So this is a way off at the moment, however if there was tax on fossil fuels for aviation then this could be competitive.

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Depending on how capital intensive the plant is, this might still be cost competitive with intermittent low, zero or negatively priced green electricity.

Also ... renewables are always going through cycles of high and low availability. Prices vary across these cycles. If you make your fuel only at the time during the day when there is the highest delta between supply and demand, then you pay the minimum electricity cost, and the utilities are glad to have you there to balance the load.

Note that this economic strategy is already in place in other industries where electricity price is a large component of the final cost of goods sold. Aluminum smelting is a huge example of this.

Large-scale Negative, zero or below-cost renewables only happen if someone else foots the bill. And that usually means tax-payer funded subsidies. I mean sure, there will be some hours during exceptionally sunny/windy days when price is less than the production cost, but don't bet your business on it.

What does work is building the plant in a wind/solar abudant location and co-siting with large, behind-the-meter wind/solar plant. Not only do you get electricity at cost, but you cut the grid costs and taxes away too.

$0.10 per kWh for solar power is a really high figure.

There's non subsidized power plants now being built for southern california, in India and in the UAE where the price for power sold to the grid is 2 to 3 cents per kWh ($0.025 to $0.030 per kWH).

My residential electricity costs about $0.12/kWh, including delivery. I don’t think that’s a realistic price for solar. Current utility-scale solar is maybe $30-$45/MWh with some estimates of $15/MWh in 2022. Obviously that doesn’t include transmission, but presumably it would make sense to co-locate fuel synthesis near generation and reduce those costs. Seems like that would make a big difference to those estimates.

> it would make sense to co-locate fuel synthesis near generation and reduce those costs

I'm not so sure about it. I believe that transmission of electrical energy is cheaper than transmission of fuel. So it would be better to collocate synthesis with airports where planes are refueled.

Jet fuel produces about 2.5kg of CO2 per litre. Since that in emitted at high altitudes, you can probably multiply this by 3 to get the actual climate impact. So a carbon tax of around $200/ton would make this competitive even with the rather high price of solar than you assume.

Maybe the question should be how long can it stay at $2/liter? That $0.50/liter advantage may be gone in a year or two but the $2/liter synthetic fue remains or maybe slightly more.

I think the problem in your calculation is the cost of grid power for industrial use is lower. I didn't look it up though.

Cost of renewables is falling fast. Getting close to 1c per kWh.

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