this post was submitted on 15 Jul 2024
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Discussion of climate, how it is changing, activism around that, the politics, and the energy systems change we need in order to stabilize things.

As a starting point, the burning of fossil fuels, and to a lesser extent deforestation and release of methane are responsible for the warming in recent decades: Graph of temperature as observed with significant warming, and simulated without added greenhouse gases and other anthropogentic changes, which shows no significant warming

How much each change to the atmosphere has warmed the world: IPCC AR6 Figure 2 - Thee bar charts: first chart: how much each gas has warmed the world. About 1C of total warming. Second chart: about 1.5C of total warming from well-mixed greenhouse gases, offset by 0.4C of cooling from aerosols and negligible influence from changes to solar output, volcanoes, and internal variability. Third chart: about 1.25C of warming from CO2, 0.5C from methane, and a bunch more in small quantities from other gases. About 0.5C of cooling with large error bars from SO2.

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A hydrogen-powered air taxi flew 523 miles emitting only water vapor (www.popsci.com)
submitted 4 months ago by [email protected] to c/[email protected]
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"Joby took a pre-production prototype of one of its battery-electric aircraft and outfitted it with a liquid hydrogen fuel tank and fuel system. The modified, hydrogen-powered VTOL was able to complete a 523 mile flight above Marina, California..."

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[โ€“] [email protected] 1 points 4 months ago (1 children)

Second, even if we were to produce hydrogen from water, the cycle of electrolyzing, transporting and using hydrogen is associated with enormous energy losses, and we still have to get that extra energy from somewhere

Is it worse than hauling enormous batteries, though? I know hydrogen looses like half the energy on generation, but to me it sounds the same as if we do all-electric and spend the same amount of energy for just moving the batteries around. I'm too cooked atm, but is anyone up to do the research/math on this?

[โ€“] [email protected] 4 points 4 months ago

Batteries take up about 15-20% of the vehicle mass and have around 90% efficiency

Hydrogen cycle has, at best, 60% efficiency (assuming amazing logistics and fuel cell for hydrogen-to-energy conversion); also, hydrogen systems also weigh a lot, but even if they would weigh literally 0kg, they would lose on efficiency anyway.