this post was submitted on 27 Jun 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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California Is Showing How a Big State Can Power Itself Without Fossil Fuels | For part of almost every day this spring, the state produced more electricity than it needed from renewable sources. (www.newyorker.com)
submitted 5 months ago by [email protected] to c/[email protected]
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[–] lettruthout 1 points 5 months ago (2 children)

Solar module efficiency is what, about 20% at best? Thermal is more like 60%. This means less roof area needed on a house that doesn't have a lot of solar exposure.

Then there's cost. With the thermal system I'm planning there will be 40gal of potentially very hot water mixed down to the (lower) maximum temperature of my 40gal electric water heater, which will again be mixed down to the maximum temperature allowed for domestic use. In effect the design will be one battery feeding into another. 'Seems cheaper than lithium batteries, and since this will be a passive system, no controller will be needed.

[–] [email protected] 3 points 5 months ago

You also have to deal with a ton of extra plumbing and envelope penetrations, and the space the thermal solar collector takes up doesn't fit nicely with a solar PV array either. A HPWH might use 800 kWh/year, so thats like less than two 400+ W panels to cover all your water heating. I think thermal solar is fine tech and there are certainly situations where it makes sense (perhaps yours) but overwhelmingly HPWH is more cost effective and simpler.

[–] [email protected] -1 points 5 months ago

Solar module efficiency is what, about 20% at best? Thermal is more like 60%. This means less roof area needed on a house that doesn't have a lot of solar exposure.

So anything above a CoP of 3 and you need less area. That's pretty doable these days. Maybe read up on how heat pumps work first before making assertions.

Also you can totally store hot water from a heat pump.

The main disadvantage is cost and complexity.