The extreme cold temperatures experienced by a large part of the United States this month have highlighted the vulnerability of power systems equipment in such extreme weather. This week’s snowstorm led to power outages in the Northeast, but cold weather alone can be enough to cause problems: The Tennessee Valley Authority, which serves 9 million people in the Southeast, urged customers Thursday to conserve energy to prevent a cold-weather outage. The average person might ask, why would my power go out when it’s just cold outside?

The electric system consists of thousands of components that are mostly electromechanical, with lots of moving parts. Like your car, these systems work best when they operate in the middle of the temperature and moisture/humidity range they were designed for.  When they are new, these devices are designed and rated to operate correctly in even extreme temperatures. But as they age—and much of our infrastructure is already operating well beyond the life span for which it was designed—they may not operate well in extreme conditions. (See related quiz: “What You Don’t Know About Electricity.”)

Most of the time, when power system equipment is subjected to extreme cold or hot weather, all is well as long as it is not subjected to stress. When it gets too cold, hot, or moist, many of these devices operate slower, faster, or less predictably than they normally would—especially when they are called upon to perform really hard work, such as a circuit breaker or switch opening fast enough to protect the system from a short circuit caused by a tree branch falling on a line. (See related blog post: “‘American Blackout’: Four Real-Life Threats to the Electric Grid.”)

Anyone who has lost electricity during a storm with high winds knows that trees and other nearby items can pose a threat to power lines. But even if there is no snow and ice to send branches tumbling onto the above-ground lines, tree roots can cause problems by providing a pathway for ice to build up around lines underground. In both cases the lines are already stiffer than usual from the cold, making them more vulnerable. (See related blog post: “Preparing for the Zombie Apocalypse: Are Microgrids Our Only Chance?“)

Wind can also cause malfunctions in the system by blowing tree limbs into lines or rocking trees hard enough to have the roots of the trees rub against the underground lines. In our survey of utility outage causes, over 40 percent of outages come from trees, and another 20 percent come from animals. In cold weather, a warm transformer can be very inviting to a small animal or bird, which can result in malfunctions.

Another issue with extreme temperatures is that consumer demand for energy is usually higher. Heat pumps are operating almost continuously, emergency heat systems and electric space heaters may be running concurrently, and other behaviors occur that cause the energy demand to increase substantially. If temperature extremes are worse than forecast and/or happen faster than forecast, the utilities may not have planned for or had enough time to bring sufficient generation online to support the demand.  This can result in local or widespread overloads that may cause service to some neighborhoods to go offline automatically or switch to rotating blackouts.

In an age when more homeowners are using solar panels to generate their own electricity, bad weather usually limits the output of these devices and increases the amount of energy the utility must supply, making the problem even worse. Self-generation of electricity by customers essentially hides the true energy demand of a residence or building from the utility, making it difficult for them to know how much energy they must be able to supply instantaneously when those self-generation sources go offline or are substantially reduced.

The power system in Texas experienced all of these problems during the extreme cold weather earlier in January.  The severe cold at some power plants interfered with the proper operation of sensors, hydraulic lines, and other electromechanical support equipment, resulting in some plants shutting themselves down. This lack of generation, coupled with an extremely high energy demand, caused ERCOT, the Texas system operator, to issue an energy alert the morning of January 6 asking customers to conserve energy—they were on the verge of rotating blackouts. Thankfully, the careful planning and conservative operating practices of the system operator allowed it to ride through these challenges.

There are many things that utilities can do to minimize the impact of extreme cold or hot weather on power system operation. Ensuring that power plants are properly insulated so that their support equipment is working is one item noted in Texas that could be done better.  Replacing aging infrastructure, adding additional status monitoring equipment, and improving load forecasting for given weather environments can also help.

All of these measures come at a cost—especially the replacement of aging infrastructure—and unfortunately, few are willing to see their electricity rates go up to pay for such improvements. At some point, aging infrastructure starts to fail more often and more catastrophically, resulting in more inconvenience for longer periods of time at much higher cost.

By the time a critical mass of the public and regulatory officials realize it, it may be too late to upgrade efficiently. We all could pay a premium for the more expensive, last-minute fix.

Erich Gunther is an IEEE (Institute of Electrical And Electronics Engineers) Fellow, board member of the IEEE Power and Energy Society and co-founder and chief technical officer for EnerNex, an electric power research, engineering, and consulting firm.

Comments

  1. Erich Gunther
    Knoxville, TN
    February 3, 5:13 pm

    Good comment on the galloping conductors – I probably should have mentioned that. Good video of the problem here: https://www.youtube.com/watch?v=1Uq03cvYdVA

    I would love to see good energy policy that takes an intelligent, engineering approach to addressing aging infrastructure – a solid techical and financial investment roadmap. Unfortunately these days the concept of an intelligent engineering approach with a technical and financial roadmap is totally contrary to how a policy maker thinks and acts! IMHO – Erich

  2. Paul
    UK
    February 3, 3:53 pm

    In the UK just a bit of wind and rain and it all seems to stop working, or it has this winter at least.

    http://www.pauldowningltd.co.uk

  3. grassroot
    google
    January 30, 10:39 am

    What ever happened to Obmer’s plan to
    rebuild our aging infrastructure? Not to mention the funds allocated for it?

  4. Roy Dane
    Michigan
    January 29, 9:37 pm

    I’m rather surprised that conductor galloping wasn’t mentioned. When you get an ice storm with enough wind ( it doesn’t take that much ) the conductor starts “galloping” just like the Tacoma Narrows bridge is doing in this video
    http://www.youtube.com/watch?v=j-zczJXSxnw . Eventually, just like the bridge, the power line comes down.

  5. Erich Gunther
    Knoxville, TN
    January 29, 10:38 am

    We all love our trees! But yes, they are a leading cause of outages. I have that problem in front of my house – but I take it upon myself to have them trimmed before the utility has to and before they cause a problem.

    No one is blaming solar for outages – it is just a fact of life and the basic physics of how a connected grid system (as opposed to totally off grid system) works. There is no easy way for the utility system to know how much actual load is being masked by local generation so when it gets cloudy fast, all that load just suddenly pops up and the utiity has to supply the energy by other means fast.

  6. Shane Copeland
    Red Deer AB Canada
    January 29, 9:35 am

    Why do they plant trees so close to power lines? Why do they place power lines so close to trees? Trees make up for 40 percent of power outages, I have to be missing something here.

  7. Lorena Mitchell
    Manitoba
    January 28, 9:07 am

    Blame solar really? Well there are lots going off grid like I did and you can not blame us!

  8. Erich Gunther
    Knoxville, TN
    January 23, 2:58 pm

    With the Super Bowl almost here I thought I would mention that major, high visibility events such as the Super Bowl require extra special attention to ensure that “all systems are go” when extreme weather may be present. My team and I were retained to assist in preparing for powering the Super Bowl – an interesting task! You can read more on that in my blog at http://www.enernex.com/blog/enernex-assists-in-superbowl-preparations/