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Comment by acidburnNSA | Hacker News Reader

There's quite good consensus on the low-carbon nature of nuclear. 12 gCO2-eq/kWh is what the IPCC group of scientists recommend [1]. That's the lowest of any form of energy, except for wind, which is at 11. Solar PV's around 40. Coal is 820.

Waste disposal and decommissioning are factored into this number, of course. It's lifecycle analysis.

Recall that the beauty of nuclear energy is energy density: there is 2 million times more energy in a uranium nucleus than in any chemical's electron shell. An average american can get 100% of their total primary energy for an entire 88 year lifetime and only use 300 grams of nuclear fuel. At that kind of fuel/waste footprint, it's relatively easy to have a low carbon footprint. And the data is in. The number is 12 gCO2-eq/kWh.

[1] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...

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With regards your other points, I'll happily concede the energy density advantages, but refer you to the other factors that plague construction of new plants (design, economics, NIMBY, etc). It may well be a 'better option' by some assessment, but not by the ones that matter, unfortunately.

The article you cited [1] quotes min/med/max numbers for gm CO2 / kWh for nuclear fission as: 3.7/12/110

Following the references, I'm directed to an annex [2] that describes the metrics & methodology behind those figures.

In section A.II.9.3.2 Nuclear Power there is only one paragraph:

"The data on nuclear power was taken from Lenzen (2008) and Warner and Heath (2012). There is no basis in the literature as far as we know to distinguish between 2nd and 3rd generation power plants."

Lenzen's mentioned in the review that I cited, but only in passing. Warner and Heath is more heavily scrutinised -- in comparison to a slightly earlier (Benjamin Sovacool, 2008) meta-analysis, which identified a range of 3-200, with an average of 66 gm CO2 / kWh -- compared to the median in Warner and Heath's meta-analysis of 12.

Keith Barnham more fully explores the metholodogical peculiarities of the Warner and Heath meta-analysis in that article I posted above.

[1] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...

[2] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...

> There's quite good consensus on the low-carbon nature of nuclear. There's quite good consensus on the low-carbon nature of nuclear.

I'm aware that it's low-carbon.

Your original claim - made twice in your earlier post - is that it's 'carbon-free'.

This is what I was suggesting was not entirely accurate.

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.

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?

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).

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

Its like the claim that electric cars are fossil fuel free. Technically they still use oil in the engine, the tires, glycol in cold temperature, and last the energy itself is likely to be generated from fossil fuels. The roads it travel on is often petroleum based.

A lot of Fossil fuel is involved when a electric car travels so a more accurate description is to call them low-carbon transportation, but no one does that.

It's rare that I hear an EV described as 'fossil-fuel free'. What may be said about them is that they are - or can be - carbon-neutral ... usually with the qualifier 'to operate'.

Manufacturing releases a lot of carbon, I agree. That's changing, but I expect the pragmatic view is that the change is best described as an asymptote.

I did mention oil for the engine, glycol, and tires, which are all considered operational costs for a car owner rather than manufacturing. Neither of those are carbon-neutral in that you extract carbon as fossil fuels from the ground and release it into the environment.

We do have manufacturing like the steel and plastic parts of the car, but those are as you say a different matter to the operational costs.

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