Renewable Limits: the power planners challenge

There is a valuable, very well-informed conversation going on at BraveNewClimate in the Renewable Limits topic. I don’t have time for details right now – but I will recommend an entry point into the conversation. David B. Benson outlines the power planners challenge:

(…) We require reliable, on demand electricity and now also low carbon. So here is an exercise which deescribes in a simplified manner the problem faced by power planners.

Every day is exactly the same as the one before with regard to electricity requirements: from 6 am to 11 pm the grid requires 28 GW and from 11 pm to 6 am 20 GW. Using low carbon tecchnologies only [NPPs, wind, solar] design the least cost [LCOE basis] system of generators to service this demand while maintaining, most of the time, a 2 GW reserve. [Or 4 GW reserve if you insist.]

If one allows thermal storage on NPPs (I see no reason why not but nobody has actually built just as yet) the least cost is NPPs with thermal storage. Such a system can encourporate up to 29% solar PV [nameplate, so maximum of 8 GW] without difficulty. The solar PV component would, on average, generate about 5.8% of the power requirement. It turns out that more than that tends to become more expensive.

If indeed one has NPPs with thermal storage then some level of wind generation would indeeed lower costs if the cost of wind turbines and transmission is sufficiently low. Unfortunately, wind turbine LCOE is now beginning to rise due to mature technology, increased costs of materials, and the best sites are already occupied. My estimates of the LCOE for wind and for NPPs with thermal storage are such that no particular advantage can be found in using the wind resource, even with the nifty thermal stores to act as balancing agents.

However, I might have misestimated and it is rather a close call. Please try this exercise yourself.

If you search all the BNC comments for “David B. Benson” you will find that David has been investing a lot of effort into an objective characterization of the energy options for a low carbon world. Hopefully there is a book in the works (?)