alt Hacker News20TW is roughly current world marketed energy consumption. But, on Earth, solar power plants have a capacity factor around 20%, so you need 100TW of solar panels to produce those 20TW. Moreover, we should expect human energy consumption to continue to grow, not suddenly become constant, especially since solar energy is so much cheaper than older sources of energy; 20 years from now we might need four times that much, depending on how AI works out. In that case you'd need to produce about 400TW÷20 years = 20TW/year.
According to the IEA, we currently have only about 1.5TW/year of manufacturing capacity: https://www.solarplaza.com/resource/13581/article-global-sol...
Hydropower is already scaled nearly to its limits, and wind energy is useful and important, but is dropping in cost much more slowly than solar, and it's tapping a much smaller resource.
Replies
> In that case you'd need to produce about 400TW÷20 years = 20TW/year. According to the IEA, we currently have only about 1.5TW/year of manufacturing capacity: https://www.solarplaza.com/resource/13581/article-global-sol...
So, at the current production rate, we can produce solar cells that deliver 20TW/year in about 15 years. Eventually, we’ll have to replace lots of them, but given that the rapid growth of installed panels makes the majority of panels new, I think we can mostly ignore that in this calculation.
> 20TW is roughly current world marketed energy consumption. But, on Earth, solar power plants have a capacity factor around 20%, so you need 100TW of solar panels to produce those 20TW.
This confuses primary energy with work. 1 TWh of solar can displace multiple TWh of primary energy. This depends on details, of course; in some cases it makes sense to directly convert solar output resistively to heat even if that takes a second law loss.