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Comment by sacred_numbers | Hacker News Reader

Transportation costs are really not that high. Let's say that the farm is 2000km away from the city. Average freight cost per ton-km via truck is about 12 cents, so an additional $240/ton. Via rail it's about 3 cents, so an additional $60 per ton. CO2 emissions follow a similar ratio, about 97 grams per ton-km for trucks and 22 grams for rail, so between 44 and 194 kg CO2 per ton.

Growing a metric ton of wheat with 100% supplemental light requires 150,000-400,000 kwh. That's $3,000 to $8,000 in electricity costs at 2 cents per kwh (very cheap) and would require electricity to generate about a gram of CO2 per kwh at the most to be better in terms of CO2 emissions.

If you have free, non-polluting electricity it would be better to use it to synthesize fuel for trucks to carry grain from the fields, or to capture CO2 from the air.

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“would be better”

There are other inputs to growing outdoors: fertilizer usage, water usage, and insecticide/pesticide usage (likely not an exhaustive list). In a controlled environment like an indoor farm the use of each of those is dramatically less than in traditional farming. It would be worthwhile to include all of the inputs of growing food since light and transportation are not the full list.

(disclosure: I work for an indoor, vertical farming company)

Yes, but does the reduction of the other cost win against the increase of cost of illumination? Do you have a table with an estimation of the cost in each scenario?

Some back of the envelope calculations: From [1] the cost of fertilizer is like $150/acre and from [2] you can get about 7 tons/acre, so it's like $40/ton. The numbers change a lot from source to source, so let's multiply that by 2, and we get $40 of fertilizer per ton.

So in the impossible best scenario where the indoor production saves you the 100% of the fertilizer, you save $40 per ton of fertilizer that is much less that the $3000 per ton of electricity for illumination.

[1] https://farmdocdaily.illinois.edu/2017/07/fertilizer-costs-i...

[2] https://www.seedcorn.com/resources/estimating-corn-silage-yi...

Even if you go full renewable fertilizer, and run Haber-Bosch process with electrolysis-based hydrogen and electricity as energy source (instead of natural gas which is currently used for both), you’d still increase the price of fertilizer by a factor of 5 at most, not getting even close to the cost of artificial illumination.

I get your points but wheat is $200/ ton[0] (US, 2019) so it transportation is potentially a significant part of the total cost.

As you said, simply finding ways to reduce the cost (in $ and CO2) of transporting field grown wheat is probably better than co-locating a vertical farm.

[0] https://www.statista.com/statistics/675822/average-prices-us...

I wonder how that electricity usage compares to bitcoin mining. And by wonder, I really wonder, as I have no idea.

Mining costs money but returns bitcoin which can be sold for money. Miners can't spend more money than they would get by selling the bitcoin and receiving transaction fees.

In theory the energy intensity of bitcoin should go down over time because the block reward is shrinking. Of course transaction fees could rise but processing transactions is different to wasting energy to mint a currency out of thin air. Paying transaction fees is like paying your taxi driver. It's expensive but it's absolutely necessary to get a ride.

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