Currently per capita usage of raw power in developed nations is about 10 kW per capita, of which about 3 kW is used to make 1 kW of electricity. The other ~7 kW is consumed by space heating, transport fuel and industrial processes such as steel and cement. Decarbonising all of these needs with nuclear would require 10 kW (thermal) for every person in the country, via electricity or not. Noncarbon power for a city of 1 million people would require ~10 GW of thermal generation. That's rather more than three times current steam generation.
Post by David B. Benson on May 23, 2019 19:19:22 GMT 9.5
The New Normal for Electricity Markets Conjures Bad Memories; Forewarned, Will We Be Better Prepared? John Harrison 2019 May 17 Northwest Power & Conservation Council
"Reliability capacity" is going to seriously decline here in the Pacific Northwest and the probability of a "major outage" in the next 10 years is around 40% unless Something Is Done. Unfortunately, it is unclear what can be done, according to this conference summary, as the 4 suggestions offered do not appear that promising.
Currently per capita usage of raw power in developed nations is about 10 kW per capita, of which about 3 kW is used to make 1 kW of electricity. The other ~7 kW is consumed by space heating, transport fuel and industrial processes such as steel and cement. Decarbonising all of these needs with nuclear would require 10 kW (thermal) for every person in the country, via electricity or not. Noncarbon power for a city of 1 million people would require ~10 GW of thermal generation.
That depends on the specific nuclear technology involved. LWRs probably would require 3.3 TW(th), but as you get higher thermal efficiency things appear to change. LMFBRs and MSRs would probably be able to do the job with considerably less.
I have stalled on my national energy analysis but I did get through the calculations on a steam cycle driven by a LMFBR assuming 550 C hot-leg temperature. Assuming 900 F 5000 psia primary steam, 2 reheats and 90% turbine efficiency I got net thermal efficiency of about 45% at 20 C turbine exhaust temp and still about 33% at 100 C exhaust temp (CHP duty using hot-water district heating). 3.3 TW(th) at 45% yields almost 1.5 TW(e), which is way beyond peak US electric consumption and even allows for electrification of most transport (PHEVs) and space and water heating via heat pumps... what's left after district heating replaces lots of NG consumption.
Transportation appears to be the easy part; many years ago I calculated US motor fuel consumption as equivalent to roughly 180 GW electric demand. Going from 450 GW average to almost 1.5 TW nameplate (1.1 TW winter) covers transport with plenty to spare. The tough nut seems to be industrial energy, which comes to something over 700 GW(th). Different industrial processes have very different temperature requirements, and the sheer number of different categories (over 1800 in the spreadsheet I downloaded) makes it extremely difficult to categorize them by their suitability for substitution.
That aside, with all regular electric demand covered and plenty to spare for e.g. electrofuels, 100% decarbonization appears to be feasible with nuclear. Further, every number I've crunched so far suggests that we'd run out of demand well before we hit 3.3 TW(th) of primary heat if we used LMFBRs, let alone MSRs.
The difficulty with LMFBRs is their poor down-sizing prospects. EBR II was a tiny machine with a core that would fit on a dinner table, yet it cranked out 62.5 MW(th) and required 67% fuel enrichment. Fermi 1 had the thermal output of a NuScale (200 MW(th) for both) and roughly the same core size, but demanded fuel enriched to 25.6% U-235. It takes something like a PRISM at 840 MW(th) to get down to 15% or so fissiles in the core (not blanket). This sets a rather high lower bound on the size of a city which can use a LMFBR for CHP; otherwise most of the heat has to be discarded even in winter. Anyone living outside the coverage of district heat will have to use electricity or supplemental fuels (ideally, electrofuels) for space heat and DHW.
Post by David B. Benson on Nov 23, 2019 19:09:57 GMT 9.5
engineerpoet, almost every summer there are reports of Rankine cycle generators shutting down in the summer because the source of cooling water is too warm. Southeast USA and southern France come to mind.
Post by engineerpoet on Nov 24, 2019 0:12:43 GMT 9.5
That's because of legal limits on water outlet temperature; the hardware is almost never stressed to any real degree. Vermont Yankee had cooling towers to reduce the water temperature by evaporation so it could continue to operate even during high temperature, low river flow events.