Shutdown Highlights A Future Without Nuclear
Last week, Xcel’s Monticello nuclear power plant shutdown unexpectedly due to maintenance work that cut power to two pumps in the plant. Resulting high water levels tripped the main turbine, leading to an automatic reactor shutdown from full power.
Thankfully, no one was hurt and according to Xcel Energy the public was never in any danger. The shutdown occurred according to standard operating procedures.
But the incident took an entire 600 MW power plant offline in a fairly short amount of time. While I don’t know of any outages that resulted from the plant shutdown, the loss of that amount of generating capacity must have wreaked some havoc on grid planners at the Midwest Independent Systems Operator (MISO). It also likely affected wholesale electricity prices as planners looked elsewhere to fill the generation loss.
MISO is a nonprofit organization that manages the constantly changing tug of war between electricity demand and supply across 11 U.S. states and Manitoba, ensuring that the lights stay on without overloading the system with juice. This very detailed video from MISO highlighting “A Day in the Life of the Grid” provides a great look at how this balancing act is achieved given numerous and diverse influencing factors.
MISO has to be “legally agnostic” when it comes to deciding which generation source electricity should come from, meaning they can’t place any preference or bias on any given generation source like coal, wind or natural gas. They are tasked, however, with providing reliable electricity from least-cost generation sources.
So at any given time, the electricity flowing into your home or business is coming from a mix of the cheapest available generation sources.
Because the nuclear plant was running at close to full power when it shutdown, it was part of that cheapest available generation mix. When it went off, a lot of more expensive electricity from another source in the area or elsewhere had to be shipped in to cover the loss.
This incident highlights the modular benefit of wind and solar energy generation sources. When a wind turbine or solar panel fails, the grid loses between a couple kW and at most 2 MW of generation. This has a much smaller effect on grid management than losing an entire 600 MW nuclear plant (capable of powering almost 500,000 homes) all at once. While it is true that turbines and panels go down when the wind isn’t blowing or the sun isn’t shining, these occurrences are easier to predict and plan for than unexpected plant shutdowns.
In addition, wind energy is often cited by MISO and utilities as being the lowest cost generation source available, and is often used in the largest capacity possible. I’ve written before that the age of large coal-fired power plants is over. The same holds for nuclear.