3 ms·

What's amazing is that human and animal muscle power used to be the primary source of mechanical power in human civilization with plants as the energy source. I

What's amazing is that human and animal muscle power used to be the primary source of mechanical power in human civilization with plants as the energy source. If you were to power an electric generator using a human, you would at most get 200W of sustained power. Today you can buy a tiny solar panel that costs less than such a generator and it will produce power expending zero human effort. Meanwhile the competing energy source, fossil fuels, is maybe 10 times cheaper than generating fossil fuels directly with the help of solar power, except the former took millions of years to form and will be depleted within a millenium, whereas the latter could, at least in theory, produce the same quantity we consume per day today, every day.

Gibbon1 2y ago
I tried some calculations comparing the amount of work energy you can get out of an acre of solar vs an acre of corn grown for ethanol. I get different numbers depending on data sources but it's around 50 times more. It's enough it sends my thoughts down the path of what if instead of green ammonia based fertilizer you start talking synthetic amino acids.
- pfdietz 2y ago
  Those complaining about the space PV takes from nature should, for consistency, start advocating synthetic food so we can get rid of agriculture.
  - Gibbon1 2y ago
    My nutter cousin likes to post pictures on facebook of rural solar farms that he claims are destroying the environment. And pictures of farms and cattle ranches that are natural. He lost his house rural house in a fire and now rents. But yeah plants are 2% efficient or something and most crops require a lot of energy input. And we've got maybe 100 years of topsoil left in a lot of places.
    - pfdietz 2y ago
      2% is, I believe, the maximum efficiency ever recorded for conversion of sunlight to food calories. The typical yield on a farm is much lower (granted, some of that goes to non-food biomass). The yield for crops grown to produce meat, especially beef, is MUCH lower. Fun fact: on a perfectly still day, photosynthesis of a corn field will be curtailed because the plants strip all the CO2 out of the available air, and do so remarkably quickly (IIRC in about five minutes in full sun.)

Gibbon1 2y ago

I tried some calculations comparing the amount of work energy you can get out of an acre of solar vs an acre of corn grown for ethanol. I get different numbers depending on data sources but it's around 50 times more. It's enough it sends my thoughts down the path of what if instead of green ammonia based fertilizer you start talking synthetic amino acids.

pfdietz 2y ago
Those complaining about the space PV takes from nature should, for consistency, start advocating synthetic food so we can get rid of agriculture.
- Gibbon1 2y ago
  My nutter cousin likes to post pictures on facebook of rural solar farms that he claims are destroying the environment. And pictures of farms and cattle ranches that are natural. He lost his house rural house in a fire and now rents. But yeah plants are 2% efficient or something and most crops require a lot of energy input. And we've got maybe 100 years of topsoil left in a lot of places.
  - pfdietz 2y ago
    2% is, I believe, the maximum efficiency ever recorded for conversion of sunlight to food calories. The typical yield on a farm is much lower (granted, some of that goes to non-food biomass). The yield for crops grown to produce meat, especially beef, is MUCH lower. Fun fact: on a perfectly still day, photosynthesis of a corn field will be curtailed because the plants strip all the CO2 out of the available air, and do so remarkably quickly (IIRC in about five minutes in full sun.)