You are probably not thinking about energy costs, or what drives those costs, when you flip on a light switch or turn on an appliance. Demand, specifically peak demand, is a primary cost driver of electric bills and understanding this concept will help you to become a better-informed consumer.
To help understand demand, here is an example: Electric energy consumption is measured in kilowatt-hours (kWh) and demand is measured in kilowatts (kW). Light bulbs have varying power ratings, and for this example we will use a 100-watt bulb. If that light bulb stays on for 10 hours, it “consumes” 1,000 watt-hours — one kWh — but only demands 100 watts.
Now, if you turn on ten 100W light bulbs in your home for 1 hour, you are still consuming the same watt-hours. However, you are placing a demand 10 times higher on the utility to have those watts available to you over the course of 1 hour, instead of 10 hours. The demand would be 1,000 watts — or one kW.
As more electric loads run simultaneously, your demand for power increases. This requires generators on the electric grid to produce more power to meet your demand. Peak demand is the maximum demand across a defined period of time.
It is easy to see why this is an important driver in the cost of providing electric service. The peak demand at your service dictates the size of wire and equipment necessary to serve you, and it drives the size of equipment as we aggregate load all the way up to the transmission line and generation resource level.
Weather and Grid Reliability
Take a moment to consider how weather affects your use of electricity. Electricity use naturally increases when temperatures reach high or low extremes. Heating and cooling systems run longer and more frequently to maintain comfortable indoor temperatures. Irrigation wells run longer during hot, dry spells to keep up with the needs of crops.
During the summer and winter months, when homes and businesses across the country are using more electricity simultaneously, overall demand can approach — or occasionally exceed — available supply. This is especially true during severe weather events, such as:
- winter storms
- long hot spells
- sudden temperature drops
- equipment malfunctions that reduce generation capacity
In rare cases when demand threatens to outpace supply, the regional grid operator may call for temporary controlled outages — often referred to as rolling blackouts — to prevent broader system failures. If such a situation arises, Highline Electric Association will work to provide timely updates and information to members.
How the Grid Stays Ready
To prepare for these scenarios and minimize risks, utilities across the grid — generation and transmission providers and local distribution companies — work together to implement proactive measures to strengthen reliability year-round.
These measures include:
- routine system maintenance
- investments in grid modernization
- comprehensive disaster response planning
- extensive resource planning processes
These proactive steps are designed to ensure our portion of the grid remains resilient even under extreme conditions.
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Dennis Herman is the General Manager of Highline Electric Association. HEA’s mission is to provide our members with reliable, high-quality electricity and other needed services, which will improve their economic and social well-being and provide significant long-range benefits for our communities, our state, and our nation.
