The US wastes about two-thirds of all the primary energy that enters its economy. Why? Because burning stuff wastes a ton of energy, and we burn a ton of stuff.
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Waste heat is part of the process of generating electricity regardless of source. Solar PV has conversion efficiencies around 20%, which is great. Much of the remainder is converted to heat. We just need to remember what gets included in those diagrams and what doesn’t.
For low carbon sources like solar, wind, hydro, geothermal, and nuclear it isn’t that important as the wasted energy isn’t generating CO2. In a few hundred years, if we get GHG emissions under control, waste heat may be the primary source of warming, though.
This has me daydreaming about what kind of orbital canopies or albedo management might be considered to balance waste heat. Probably pretty modest when GHGs are flat.
The waste heat is not that big a contributor. A nuclear plants' waste heat is on the order of a few months of forcing for a coal plants CO2. If we get to the point of atmospheric carbon removal, a relatively minor 'undershoot' of the CO2 would accomdate any reasonable level of waste heat.
Space solar at earth-sun L1, for limited bandwidth, high power consumption compute. Far enough away that we wouldn't actually see the platform, but it would cast a diffuse shadow proportional to the collection area.
The only real space solar possibility that doesn't end out with 'death rays'...
I think the higher land area use is the main impact of lossy renewables. If the efficiency increases you can use less land which increases land productivity.
With fossil fuels we effectively pay for both the wasted energy and the useful energy in our bills.
I did the math and solar PV in the desert is 54% efficient when considering waste heat vs. background albedo. Grassland solar is more efficient. What's weird, doing it this way, is it goes over 100% if the panels are over dark water.
I did this calc to debunk some nonsense circulating about how solar panel heat islands were changing the weather, causing tornadoes or whatever. And I'm like, if you're worried about power plants changing the weather with thermal waste, look no further than coal!
I looked at this as a contributing factor to urban heat islands. It was less than black tar roofs and dark pavement, but was still troublingly high for rooftop PV. Coupling it with good UHI mitigation seems the best approach.
An Arizona group modeled it with cool and conventional roofs in the hot+dry AZ climate. Cool roofs are a sl dunk for cooling and cost effectiveness. PV is cooling but expensive. Using PV to run AC and dumping heat outdoors negates PV cooling somewhat
A few decades ago, a social scientist remarked that in order for everyone on Earth to have the standard of living that Americans have, population would have to reduce by 90%.
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The only real space solar possibility that doesn't end out with 'death rays'...
With fossil fuels we effectively pay for both the wasted energy and the useful energy in our bills.
I did the math and solar PV in the desert is 54% efficient when considering waste heat vs. background albedo. Grassland solar is more efficient. What's weird, doing it this way, is it goes over 100% if the panels are over dark water.
I looked at this as a contributing factor to urban heat islands. It was less than black tar roofs and dark pavement, but was still troublingly high for rooftop PV. Coupling it with good UHI mitigation seems the best approach.
That wasteful.
Yes, 2/3 goes unused, but much of that "waste" was never available to us in the first place.