james_davis_nicoll (![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
james_davis_nicoll) wrote2005-03-09 02:11 pm
james_davis_nicoll) wrote2005-03-09 02:11 pm
Efficient food production
I was noodling around on soc.history.what-if and made a calculation I'd never bothered with before: if a human needs enough food to produce N Watts, how many square meters are required to intercept that much sunlight? OF course I was too lazy to actually look up insolation for various latitudes but the BOTEC I committed seemed to show that it should be a few square meters.
Even Fairbanks, Alaska, gets from 90 to 350 watts/m^2. Say your mark 1 human needs at least 100 watts worth of food to keep functioning [1]: They'd need about one square meter dedicated to collecting solar powers, asssuming no losses. The entire population of North America should require a few hundred to a thousand square kilometers of converters to power themselves. Even a factor of ten losses should mean that we'd need about 300 square kilometers to feed all of Canada, assuming the lowest insolation in Alaska is what we have to work with, and about 3000 square kilometers to feed all of the USA. That's a square less than 20 kilometers on an edge for Canada and a bit over 50 kilometers on an edge for the USA. Feeding the entire planet should require about 60,000 square kilometers or a square about 250 km on an edge (or less, if we pick someplace sunnier than Fairbanks to grow food).
Clearly modern methods of coverting solar (and fossil) energy into human energy are criminally inefficient.
1: Googling says "at least 2500 kilocalories" per day so call it 4000 to be safe. That works out to about 50 watts, which I will double just because.
Even Fairbanks, Alaska, gets from 90 to 350 watts/m^2. Say your mark 1 human needs at least 100 watts worth of food to keep functioning [1]: They'd need about one square meter dedicated to collecting solar powers, asssuming no losses. The entire population of North America should require a few hundred to a thousand square kilometers of converters to power themselves. Even a factor of ten losses should mean that we'd need about 300 square kilometers to feed all of Canada, assuming the lowest insolation in Alaska is what we have to work with, and about 3000 square kilometers to feed all of the USA. That's a square less than 20 kilometers on an edge for Canada and a bit over 50 kilometers on an edge for the USA. Feeding the entire planet should require about 60,000 square kilometers or a square about 250 km on an edge (or less, if we pick someplace sunnier than Fairbanks to grow food).
Clearly modern methods of coverting solar (and fossil) energy into human energy are criminally inefficient.
1: Googling says "at least 2500 kilocalories" per day so call it 4000 to be safe. That works out to about 50 watts, which I will double just because.
Hasn't Drexler been more or less marginalized?
It's a shame the term "nanotech" has been irredeemably tainted by the more extreme proponents. I don't really want to use the term "biochemistry" because what if I'm talking about something designed with real biochem in mind but not using anything that is actually used on Earth?
Re: Hasn't Drexler been more or less marginalized?
drexler is largely marginalized by serious chemists, but afaik, he still has a large following among nano-ninnies and random lay people.
Re: Hasn't Drexler been more or less marginalized?
(Anonymous) 2005-03-10 12:44 am (UTC)(link)(There's a whole strange subclass of MIT-affiliated whoopsies like that. Norbert Wiener's wife claiming McCulloch seduced their daughter, setting back cybernetics a decade. Minsky and Papert stomping on perceptrons, setting back neural net research a decade. Chomsky and linguistics, setting back linguistics two, three decades. Various Media Lab things.)
For a neologism, might I suggest "artificial biochemistry"?
Carlos