this post was submitted on 21 Sep 2023
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Yes exactly this. Indoor farming uses many, many orders of magnitude more energy than traditional farms. Low-Tech Magazine (one of my favorite publications on the internet) did a write up where they discuss actual experimental results on how much more land solar powered indoor farming uses than just traditional farming.
If we use their energy measurements for vertical farming, and compare them to published amounts of fuel used per acre of cereal crops to get a rough comparison, we conclude that vertical farming is about 157,827 more energy intensive than traditional farming — a whopping 5 orders of magnitude.
cereal crops? Most implementations of these that I am aware of are greens that are being grown in a metropolitan area in order to be close to point of sale. The idea is it is clean and does not need to use pesticides and such. So it is equivalent to the most premium of greens. Pluse it does not get the ecoli contamination that happens way to often with greens. Then there is the water intensive nature of greens which is easier to minimize water with these setups. So it would be interesting to see the comparison with greens rather than cereal.
Cereal crops are just the information that's easily available. It's not a perfect comparison, but still, 5 orders of magnitude is a shocking result. That's the average American's daily commute distance vs the distance to Venus. Any reasonable use of indoor farming must somehow overcome how mindbogglingly energy intensive it is.
Woulf shipping offsets not be even to even things out, assuming we use these for local supply chains?
No way. Shipping things to market once uses very, very, very little energy when compared to continuously replicating the sun indoors with artificial lights for months.
I think you're underestimating the time and resource impact of transporting tons of food, often refrigerated, from the middle of nowhere to dense urban centers.
With enough renewable energy, the emissions cost of replacing the sun indoors could be zero.
No, I'm not. Moving things, even refrigerating them, takes so, so, so much less energy than replicating the literal sun for months. The sun gives you approximately 1,360 watts per square meter. That's 117 million Joules of energy per day per square meter for the entire area of that operation, which conveniently happens to be very close to Joules in a gallon of gas (~120 million).
In other words, for every single day, for every single square meter of an indoor operation, you need to use the equivalent amount of energy as is in a gallon of gas to grow things indoors. That's ~4,000 gallons of gas (or the renewable equivalent) per day per acre, which is not that big of an operation.
A quick google tells me that lettuce, probably the least energy intensive crop, can harvest about 10 tons per acre. According to the railroads, which might be a dubious source, a gallon of gas can move a ton of freight about 100 miles on a railroad. To move an entire acre's worth of lettuce by train 3000 miles, approximately the entire width of the US, would use only 30 gallons of gas.
Even if they're exaggerating by a several orders of magnitude, there's just no way for vertical farming to come out ahead on that.
If you truck instead, a quick google tells me that a truck's average fuel cost per mile is between 30 and 40 cents, and a truck can carry about 10 tons. In other words, moving our acre of lettuce takes about 1 gallon of gas per 10 miles. Even if we move that 3000 miles, we're only using 300 gallons of gas (or the energy equivalent). Again compare that to using 4,000 gallons of gas per day on the vertical farms. Over a 2 month growing period, that comes out to 240,000 gallons of gas.
In other words, trucking things all the way across the country uses 800x less energy than an indoor farm with 0 transportation costs would use to grow it.
The thing is, you don't need to reproduce the full power of the sun. All you need to produce, is the particular wavelengths of light which are absorbed best by the chlorophyll in the plants. And with modern LEDs, the power consumption is tiny.
With wind, solar, and geogermal energy production, one could theoretically power, and regulate the temp/humidity in the facility with a net 0 carbon emissions. Not a few hundred thousand gallons of gas....
Still doesn't work out. These people are bragging that their farm uses only 600kw/hr per meter, which is still 2% of what the sun gives you for free. Even if you divide every result I got by 50 to do that conversion, you're still using 40x more energy growing it than trucking the resulting product the entire way across the country.
When the energy is essentially unlimited, who cares how much energy it uses. None of that energy is burning fossil fuels.
Not mention all of the cost and resources saved on water, fertilizer, and the fact that you can grow all year round.
That's fine, but energy is not unlimited and probably won't be anytime soon. I think it's important to understand the realities of indoor farming. I find many in environmental communities like this one labor under the same misapprehensions that I found in this thread, and as a result have an unrealistically charitable outlook on them.
True, but renewable energy will be essentially unlimited at some point. Where as fossil fuels will never be.
Also, we can use vertical tech in greenhouses for free sunlight. It doesn't have to be a box warehouse.