2 ms·

Ah, gotcha. So then, would you say that nothing is literally carbon-free, and the phrase can never be uttered without being disingenuous? I usually use it for

Ah, gotcha. So then, would you say that nothing is literally carbon-free, and the phrase can never be uttered without being disingenuous? I usually use it for any process that doesn't require combustion. Splitting atoms is carbon free, as is solar PV, but both require various lifecycle work that inherently emits carbon since 81% of our world energy is from fossil. Nuclear or solar or wind could all become carbon free if we phased out fossil fuel. Biofuel and hydro (because of biogenic methane) can not.

jessaustin 7y ago
Technically, releasing methane into the atmosphere also requires no combustion. That seems like the wrong criterion in this thread.
Jedd 7y ago
So I think we basically agree ... except for the interest in building more fission nuclear plants. ; ) You've suggested it's close to zero carbon by selecting the median value in one meta-analysis. Specifically the 3.7 / 12 / 110 figures for min/median/max. The mean wasn't supplied - I presume it's substantially higher than the median -- so I'm wondering how much credence you have in those figures, and why we should be ignoring the large disparity in those figures?
- acidburnNSA 7y ago
  I won't deny that there is some regional variability in the carbon intensity of energy systems. As mentioned elsewhere, France uses nuclear power to run nuclear fuel enrichment and reprocessing services, where some places in the US use coal. Thus, nuclear in France is lower-carbon than nuclear in the USA. Given that increasing nuclear's share would proportionally decrease nuclear's carbon intensity, and that nuclear at worst is ~10x less carbon-intense than the current average energy mix, I say it's OK to use the median values from that table for basic energy system comparison purposes. Note also that utility PV max is 180, and hydro max is 2200 (2x coal's median!) because of uncertainties in biogenic methane. So if we compare the max of each in this table, we make roughly the same energy system decisions as if we compare the median (again, except for hydro, which we'd have to phase out rapidly if that max is realistic).

jessaustin 7y ago

Technically, releasing methane into the atmosphere also requires no combustion. That seems like the wrong criterion in this thread.

Jedd 7y ago

So I think we basically agree ... except for the interest in building more fission nuclear plants. ; ) You've suggested it's close to zero carbon by selecting the median value in one meta-analysis. Specifically the 3.7 / 12 / 110 figures for min/median/max. The mean wasn't supplied - I presume it's substantially higher than the median -- so I'm wondering how much credence you have in those figures, and why we should be ignoring the large disparity in those figures?

acidburnNSA 7y ago
I won't deny that there is some regional variability in the carbon intensity of energy systems. As mentioned elsewhere, France uses nuclear power to run nuclear fuel enrichment and reprocessing services, where some places in the US use coal. Thus, nuclear in France is lower-carbon than nuclear in the USA. Given that increasing nuclear's share would proportionally decrease nuclear's carbon intensity, and that nuclear at worst is ~10x less carbon-intense than the current average energy mix, I say it's OK to use the median values from that table for basic energy system comparison purposes. Note also that utility PV max is 180, and hydro max is 2200 (2x coal's median!) because of uncertainties in biogenic methane. So if we compare the max of each in this table, we make roughly the same energy system decisions as if we compare the median (again, except for hydro, which we'd have to phase out rapidly if that max is realistic).