adoughoskins t1_ixdkb8k wrote
How does this 'not' contribute to global warming?
Reddit-runner t1_ixdtdmi wrote
How would it?
Our problem is NOT the release of energy here on earth. Our problem is the CO2 in the atmosphere that captures the suns energy.
Edit: words
seiggy t1_ixer3e4 wrote
>The wavelength they're proposing usage of is significantly large enough to make the amount of energy negligible to any life in the path of the beam. The receiver dish is between 3-10km in diameter, and if you were to walk out on the dish during the night you would be exposed to about half the amount of radiation as you would walking around in the midday sun. So no, not very dangerous. You do realize that the Sun bombards us with massive amounts of microwave radiation already? This is simply enhancing and focusing that energy to a point where we can more efficiently collect it 24/7 instead of simply during the daylight. And the loss to the atmosphere is estimated to about about 1.5-2%. We're talking miniscule amounts compared to the energy the sun pours into our atmosphere. Not to mention, you would also be reducing consumption of fossil fuels by a significant amount, thus actually overall reducing the amount of energy added to the atmosphere. Assuming 2% of a 30GW space solar energy plant, you're looking at 600MW of energy being lost into the atmostphere. To produce 30GW of energy on fossil fuels, you're dumping about 70,000 metric tonnes of carbon dioxide into the atmosphere each year. CO2 is dangerous in the atmosphere because it happens to vibrate and absorb energy in the Infared spectrum, not Microwave spectrum. Microwaves at the energy level proposed here would not excite water molecules or CO2 molecules in the atmosphere, thus it would not increase the thermal energy in the atmosphere by any significant amount.
Copying my response to someone else above.
rocketsocks t1_ixh21oa wrote
Oh yeah, it totally would, let's check the scale of the problem to see if it's a concern.
Annual global energy usage is about 500 million terajoules per year. If all of that energy is gathered off Earth and beamed to the planet that would ultimately end up being released in the form of heat, which would potentially heat up the Earth.
In contrast, the amount of excess heating due to human caused greenhouse gas emissions translates to about 24,000 million terajoules per year, which is fifty times more heating. So replacing any carbon emitting heat source with space based solar power would still be objectively vastly advantageous in terms of reducing global warming.
IXICIXI t1_ixere31 wrote
Layman here — but this is not like a microwave oven appliance. The appliance doesn’t exactly produce heat to warm food. It fires microwaves at a finely tuned frequency to excite the water molecules in your food which makes them hot (correct me if I’m wrong here please). So I’m assuming the microwaves used in this project would be tuned differently so as not to excite our atmosphere.
rocketsocks t1_ixh263o wrote
Ultimately it doesn't matter how the transfer is made, it's the question of usage. Importing energy to Earth then using it would technically generate heat. But it's such a tiny amount compared to global warming heating that it's not worth worrying about at the current scale.
IXICIXI t1_ixijgjs wrote
Is this a matter of adding more energy to the system than there otherwise would have been without intervention?
rocketsocks t1_ixj39uk wrote
Yep. But whether it happens with burning coal that was buried forever or using sunlight that wouldn't have landed on Earth the result is the same. Replacing fossil fuel power generation with space based solar is net neutral with regard to direct heat production but avoids the generation of greenhouse gases which result in orders of magnitude more heating of the Earth (due to trapping heat that would otherwise have escaped), so it would be a huge win in that case.
Compared to where we are now, worrying about the impact of direct heating from human activities would count as a "nice problem to have".
IXICIXI t1_ixk32r6 wrote
I couldn’t agree more. Thanks for the response.
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