I read an article today about people running hydroponic farms in small spaces, the kind of spaces you might find in a crowded city. The key is to use LED lights and make the farms highly vertical, so you get a lot of plant growth in a relatively small footprint.
The LEDs are only 50% efficient in their use of electricity — the other half turns into heat. So in some ways it’s a bit energy wasteful, and the electrical bill is usually quite steep.
But it occurred to me that if we look at this from a more global perspective, it might make sense to link solar power in one part of the world to electric hydroponic farming in another part of the world. Why not harvest solar energy in equatorial deserts, where it can be done efficiently, and then pipe the resulting electricity away from the equator?
You could then have electric hydroponic farms in more frigid climates. The people in those climates would then be able to get freshly grown food, right from their own neighborhood.
Also, 50% of the piped electrical power that dissipates into heat could also be harvested. In particular, it could be used to heat peoples’ homes.
Wouldn’t this solve two problems at once?
I believe the trouble is that transmitting electrical energy over long distances involves significant losses. There are certainly many instances of power transmission over hundreds of miles, but the efficiency isn’t nearly as good as when the power can be generated near the user. The losses can be partly offset by stepping up the voltage before transmission, but that’s also a somewhat inefficient process.
Capturing and using waste heat is not uncommon. Even my tiny little college had a small cogen plant.
The power for the electricity doesn’t need to arrive quickly. So there might be an advantage to converting the electric power, for shipping purposes, to some easier to transport form of storage (perhaps hydrogen), and then converting back to electricity at some location geographically near to the hydroponic plant.
At that point you’re looking at the inefficiency of converting between electrical energy and stored energy (current techniques for producing hydrogen via electrolysis are about 67% at best), the energy required to ship that stored energy cross country, and the inefficiency at converting that stored energy back to electricity (about 85% for a fuel cell when capturing and re-using waste heat). Electrical transmission lines would be a lot more efficient. It might be practical using very high voltage (>2 megavolt) underground DC transmission lines.