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MidAmerican’s electric delivery system is connected to a regional grid that’s managed by an independent entity called Midcontinent Independent System Operator, or MISO.
Transmission lines in a field
Think of MISO as the air traffic controller of our regional grid system. MISO makes sure there’s enough power available throughout the region, and that the power on the system gets to wherever it needs to go, whenever it’s needed.
If there is a situation where energy supply and demand is mismatched, MISO may direct member utilities, like MidAmerican, to reduce overall usage.
MidAmerican has plans in place to work with MISO to reduce demand and mitigate customer impact. Our plans include opt-in “demand response” programs like SummerSaver for residential customers and for large commercial and industrial customers who choose to enroll, MidAmerican’s Curtailment program is designed to reduce their energy usage quickly.
High voltage transmission lines running from the foreground to an electrical substation structure in the background
Additional steps, if needed, would include a public request for voluntary energy conservation, called a Peak Alert. During a Peak Alert, MidAmerican asks all customers to reduce their electric usage to help ease pressure on the grid.
In the unlikely event that those measures don’t meet the energy reduction MISO requests, it will require utilities to “shed load.” MidAmerican has a detailed contingency plan to implement controlled, rotating outages for groups of customers in what would most likely be 60 - 70-minute intervals. The load shedding process is often referred to as rolling blackouts.
A rotating outage is a last resort to help protect the regional grid’s equipment from being overloaded, which could result in serious system damage and the potential for a more widespread and longer power blackout. A rotating outage event would end as soon as MISO determines that regional grid conditions have improved.