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Even without global warming from greenhouse effects, there are limits. Starting at current world energy use of about 5e20 joules/year, and a modest 2% yearly g
by wcoenen 8y ago
Even without global warming from greenhouse effects, there are limits.
Starting at current world energy use of about 5e20 joules/year, and a modest 2% yearly growth, it would take only about 500 years to get to the level of power that the Earth receives by the sun, about 5e24 joules/year. We'd be in trouble long before that.
Because if all that comes from renewables on Earth, there'd be no sunlight left for the biosphere. If it comes from nuclear or offworld sources, then per thermodynamics all that energy becomes waste heat and you have a second sun worth of heat to deal with.
- dsfyu404ed 8y ago>Because if all that comes from renewables on Earth, there'd be no sunlight left for the biosphere. If it comes from nuclear or offworld sources, then per thermodynamics all that energy becomes waste heat and you have a second sun worth of heat to deal with. Suck enough greenhouse gasses out of the air and you'll need that waste heat
- dalbasal 8y agoThat's the spirit! So... You're saying we can increase energy consumption by 20,000X before we encounter hard engineering problems like building an offworld heat waste dump? As far as the sun being insufficient, nuclear. I like the moxy, but let's go for a modest 1,000X by 20x0.
- wcoenen 8y ago> So... You're saying we can increase energy consumption by 20,000X before we encounter hard engineering problems No, I think we would run into serious issues already at 100 times current use, or "1% of an extra sun" worth of power. And that's only 230 years away at 2% growth rate. Or even just 60 years at 8% growth rate. (That's what oil growth was like before the oil shocks in the seventies, so plausibly what would happen if we got something like cheap fusion.)
- dalbasal 8y agoOk I'll take 100x for now. We can renegotiate later.