You may have seen recent national and state news coverage about the reliability of power supplies this summer. We thought you might want some background on:

·         what Duke Energy Indiana does to prepare for periods of high electric demand;

·         our membership in the Midcontinent Independent System Operator, or MISO, the regional power coordinator; and

·         how an energy emergency may affect customers.

Preparations for when power is needed most

We prepare carefully year-round to meet electric demand during extreme weather – whether the heat of summer or the cold of winter. First, we do comprehensive, long-term planning to ensure adequate power reserves. We also do advance maintenance on our power units in the spring and fall before times of higher electric demand to help ensure our power generation is ready for the summer and winter. Our meteorologists track weather, and our system operators monitor the electric power system 24/7 to keep an eye on power demand and supplies. We also have robust, voluntary programs such as PowerShare® that contractually require our participating customers to reduce their power usage in exchange for incentives that help lower their overall electric costs. This program is deployed as a first layer of defense and when it’s most needed on the system. We are active in the power markets and make arrangements to supplement our own power generation when needed with power purchases from the MISO market. Finally, we are investing in the electric grid – the power delivery system of power lines and substations – to strengthen it against extreme weather and improve the reliability of our power delivery.

Midcontinent Independent System Operator (MISO)

The electric grid is interconnected, and Duke Energy Indiana operates as a region through MISO, an independent, not-for-profit, member-based organization responsible for operating the electric power grid across 15 U.S. states and the Canadian province of Manitoba. Duke Energy Indiana has been part of MISO for more than two decades. As a grid operator, MISO’s role is to ensure the right amount of electricity is generated minute by minute and transmitted safely and reliably across high-voltage transmission lines. Local utilities, which own the power generating facilities, are responsible to deliver the electricity to their customers.

Through MISO’s transmission system planning processes, MISO works to ensure generation resources can be used to efficiently serve electric demand across a broad and diverse geographic area. The large size of MISO reduces the likelihood of extreme weather conditions existing in the entire geographic footprint. That allows member utilities to access other companies’ power generation resources during times when they need power. It also provides an avenue for power sales when they have a surplus. MISO’s size also has advantages in that it can more easily absorb an event such as a power generating station going offline. In a regional transmission organization such as MISO, there are far more avenues to import power from other regions than a stand-alone utility would have. There also are benefits of increased access to renewable energy, such as wind to the west and hydropower in Manitoba. You can learn more about MISO here.

Electric Emergencies

Organizations, such as Duke Energy Indiana and MISO, operate under federally mandated standards that require us to keep the high-voltage system secure, without harming critical components such as power generators and transformers. If certain conditions are met, MISO may require member utilities in a region to take specific actions. Except under rare circumstances, this has no noticeable impact on the customer.

Recent news coverage has focused on the most extreme event – requiring utilities to temporarily interrupt service to some of its customers to protect the system. Utility equipment, as well as customer-owned equipment and appliances, can be seriously damaged by voltage problems that occur if customer demand is exceeding supply on the electric system, and uncontrolled blackouts could happen if the system collapses. That’s why in the event of power shortages during an extreme weather event, MISO may direct its member utilities to reduce power demand on their systems through temporary, controlled power interruptions in order to ensure the electric grid remains stable. If this would ever occur, utilities would try to limit impact on customers as much as possible. Controlled service interruptions such as this are an absolute last resort.

Prior to this step, there would likely be voluntary calls for power conservation to try and balance demand with supplies on the electric grid. Voluntary conservation can have a critical impact and can help utilities avoid having to interrupt service. In those instances, we would reach out to the public and, in particular, large industries and power users asking for conservation.

In addition to power supply emergencies, utilities also may need to take emergency steps due to power transmission problems. The steps associated with transmission emergencies are similar to those taken for power supply emergencies. Transmission emergencies are usually, but not always, associated with a specific geographic area, or larger municipality. If enough of the power lines delivering power to a particular area are lost, for example during a storm, the remaining lines are in danger of becoming overloaded. This can be compounded by high energy usage and electric demand. Because severe overloads also can damage equipment, transmission system operators such as Duke Energy take mitigating actions. Temporary, targeted, service interruptions are used to protect both the area’s electric infrastructure as well as customer-owned equipment and appliances.

Utilities such as Duke Energy have multiple tools to help avoid power emergencies. We know that reliability of our service is essential, and we’re committed to ensuring it. If you have questions, please contact me.