It is imperative that we cease using fossil fuels and move to low carbon energy sources. For electricity that means all nuclear energy, all renewable energy, or a combination of the two. I have carried out a little study to see, at least at a basic level, what it might cost to create an all nuclear grid for CAISO (California Independent System Operator) members. The combined four electricity grids in California.
I used 2017 California demand data that is available on the web. I have similar demand data for ERCOT and will do a similar analysis on that data at a later date. Obviously one year of data for one set of grids does not fit all. But it should offer some insight into what would be required on a larger level. For every grid there is a daily variation in demand and all grids operate with seasonal differences throughout the year.
This is ‘stage one’ of a 100% nuclear grid for California based on 2017 hourly loads and all current cars and light trucks becoming battery powered.
Some basics about the model...
1) “Reactors” are 1135 MW reactors such as the AP1000. It is assumed the reactors would be able to load follow to some extent
2) Nuclear cost used is Lazard’s 2017 unsubsidized LCOE for new nuclear which ranges from $0.095 to $0.135/kWh.
3) Cost of detailed load matching (integration costs) are not included. Something such as batteries would be needed to match supply and demand on a finer grain level than reactors are capable of doing.
4) The cost of backup for unscheduled reactor failure is not included.
Upon running the model it was found that it would take somewhere between 30 and 35 1135 MW reactors to produce enough electricity to supply hourly load without storage or other sources of electricity.
That is 100% penetration and would mean that roughly 25% to 35% of the electricity produced would be unneeded (curtailed). The cost of generating would be $0.18 to $0.20/kWh (plus backup and integration costs).
If all CA cars and light trucks were battery powered increasing the number of reactors to somewhere in the 40 to 45 count range all light vehicles could be charged each day, replacing the electricity used for that day’s driving.
The cost of electricity would be in the $0.16/kWh to $0.18/kWh range. But that would be the cost of generation which is even less than the wholesale cost of electricity as it includes no cost for transmission or owner profit.. California’s retail rate for electricity is $0.15/kWh (Jan 2018).
It’s possible that adding some storage could decrease the number of reactors. I’ll model that in later. But with the Lazard median cost for PuHS being $0.175/kWh I can’t see storage helping. It would take much less expensive storage.
It’s also possible that selling some of the curtailed electricity for other uses such as desalinization would lower the cost but that would probably be more than offset by the costs not included.
Not included in the model is the cost of integrating large amount of nuclear onto the grid. We can assume newly built reactors would be able to load follow to some extent but some amount of more flexible supply (probably batteries) would be needed for the second to second flexibility needed to maintain frequency and voltage control.
Plus there is the issue of reactors unexpectedly dropping off the grid. I don’t have enough data to make a definitive statement on the number of backup reactors which would be needed but some data on which to base a guess.
Over a six month span beginning in September 2017, 17 of 98 or 17% of all US reactors dropped offline for reasons other than scheduled refueling and maintenance. A greater than 30% failure rate on an annual basis. The number of shutdowns may have been higher. Sometimes it’s been months after the shutdown that I stumble over the news.
Some number of extra reactors would need to be running at reduced loads, ready to take up if one of the fleet dropped out. And the reserve would need to be generous because sometimes one or more reactors can go offline for extended periods. If a reactor is lost like, for example, Three Mile Island there needs to be a reserve reactor for permanent replacement. We wouldn’t be able to wait five to ten years for a replacement to be constructed.
If we decided that we needed 40 reactors and 8 more for backup that would mean an increase of 20% in the cost of electricity.
In January 2018 the retail cost of electricity in California was $0.15/kWh. Even at $0.16 for nuclear adding in $0.05 for distribution would drive the retail cost well over $0.20/kWh and have a significant impact on the economy.