this post was submitted on 19 Apr 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.

Recommended actions to cut greenhouse gas emissions in the near future:

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'No place in our homes' | Hydrogen blends leak twice as much in household cookers compared to gas: report | leakage rate is likely to wipe out any climate benefits of using H2 in the first place (www.hydrogeninsight.com)
submitted 7 months ago by silence7 to c/climate
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[–] Thevenin@beehaw.org 12 points 7 months ago

Youtube videos often gloss over the details for the sake of uninhibited futurism.

Large-scale hydrogen electrolysis has a cost of around 55kWh/kg, and when you combust the H2 directly you get about 39kWh/kg back. Without compression/transport, using H2 as a heating fuel is 71% efficient.

H2 is usually compressed for transport. Compression of 1 kg of H2 to 700 bar costs about 5kWh of additional electricity. I'll spare you the calcs, but truck transport is under 1kWh/kg H2. This reduces our efficiency to 39kWh/61kWh or 64%.

Converting H2 to ammonia takes the place of the compressor and truck. 2 mols of ammonia burn for 162kcal, less than the 204kcal you'd get from 3 mols of H2. The Haber-Bosch process reduces output to 31kWh per kg of H2 put in. This reduces out efficiency to 31kWh/55kWh or 56%.

With currently-proven cracking technology, it costs around 23kcal/mol of ammonia, reducing overall efficiency to about 55%. It is more effective to burn ammonia directly than to convert it into H2 and burn the H2.

Using ammonia as a transport medium removes a bunch of technical problems, but it introduces new ones. It's corrosive, it's toxic, it burns eyes/lungs/skin, and it wastes more energy than you'd think.