Some replies to questions posed so far, in the previous comments thread (and one on Twitter). Disclaimer: These are my personal opinions and/or represent my synthesis of the evidence I’ve seen. Caveat emptor.
Hank Roberts: Thoughts about proposed small nuclear reactors, please.
Difficult to licence, especially in Western markets. This is why the designs for the first-of-a-kind deployments will resemble small versions of monolithic light water reactors, whilst still embracing some of the innovations that come with being, well, small. NuScale is the current front-runner. SMRs are currently uneconomic, being caught in a Catch-22 situation. In theory, they might be cheaper and faster to build than large LWRs, if one settled on a standard design and made them in a tooled-up factory. But until the bulk orders are flowing, such factories are hard to justify and finance. Unfortunately, everyone wants to build the second one.
Bernard: I’d be interested in updates on economics of various energy sources, given the changes over the past five years. I also keep seeing/hearing people talking about CCS at work, and they seem to have rather, um, optimistic outlooks on that technology…
The default outlook on all emerging-energy technologies is too optimistic. Everything is going to take much more time than the new-energy Pollyannas would like to think. Vaclav Smil’s point, in a nutshell, has always been that energy transitions take way longer, and are more expensive, than the optimists/promoters of the day would hope. I used to think he lacked vision. But the past five years have proven him right. The next five will too.
Juho Laatu: Why has no country and no party taken (or even promoted) serious concrete steps to solve the obvious and imminent problems?
It’s in the self-interest of individual nations to be a technological- and economic-policy late movers (on energy transitions), and the required global cooperation is really hard to lock in. So few move, and those that do go slowly, or do it for other reasons (e.g., energy security). The impact of climate change is becoming more obvious each year, but it still doesn’t seem imminent to enought people, because most change is not threshold like, but is incremental. And the potentially nasty threshold-like impacts (e.g., tipping points for climate feedbacks) haven’t happened yet.
Pat Cassen: I would like to see an assessment of the issue described in this recent article in Science on the NuScale SMR passive cooling system.
Passive cooling systems are one of the big technological benefits of SMRs in general. They’re innovative for water-cooloed reactors, and transformative for liquid-metal or -salt cooled reactors. The Science article is here. As you can see from this diagram, the whole reactor is submerged:
NuScale’s case for how the passive cooling works is described in detail in the linked article. The critique, Edwin Lyman, is a go-to academic devil’s advocate on advanced reactors. His assertion amounts to the argument that it is irresponsible to claim safety benefits until the design is actually confronted by a real emergency. This has some merit, and I suspect they’ll have to do this with their demo reactor. Note that this was already one for EBR-II, the prototype of the IFR, and it passed with flying colours.
Paul Dalby: what is your best guess on where global temperatures will end up before we reach some sort of new equilibrium. Not what you hope, what you think is most likely.
The fast-feedback climate sensitivity seems to be in the range of 2.8 to 3.5 celsius (the range over 26 models in CMIP6 was 1.8 to 5.6 C). Ultimately, slow-feedbacks might double this, but will be, well, slow (multi-millennia). Bending the global CO2 emissions trajectory to a negative slope will take many more decades, such that I expect atmospheric CO2e of 550-600 ppm by 2100. That suggests a planetary heating of 3 to 5+C above pre-industrial. I doubt we’ll see this though, the impacts would be too severe to countenance. Instead, I’m persusaded by David Keith that we already have the capability of turning down the global-climate thermostat with geoengineering, cheaply and efficiently — most especially solar radiation managenent— albeit with undesirable side-effects. In theory, a nation (or even a multinational corporation) could do this, unilaterally. A great hope is that we’ll find cost-effective and scalable ways of CO2 draw-down too.