October 2023 Back Page – Energy Storage

Posted: October 4, 2023

Daylight Saving time is the practice of advancing clocks forward in the spring and backward in the fall to shift how daylight hours overlap with traditional working hours.  It has never had great benefit in our northern latitudes, other than to give those that like to grumble something to gripe about.  With the wild swings in daylight hours, it seems to make little difference if the sun comes up at 2AM or 3AM on some summer morning.  Those that like to gripe point out that TRUE daylight savings would allow us to save the daylight and give it back at night, or better yet in the winter.

With the improved performance of battery chemistry and advances in inverter technology, we can now do that.  (Inverters are equipment that convert direct current (DC) from batteries to alternating current (AC) for power system use.)  We can now store energy from daylight, wind, or water movement at a large scale and use it at a later time.  Advances in this technology are presently only economical for time-shifting energy for up to a couple hours, we are not quite up to using chemical batteries to save summer energy for winter use.

Traditional power plants without energy storage rely on control systems to regulate generators and adjust engine speed to provide the exact amount of power needed every second of the day, no more, no less.  With energy storage we can now incorporate more of the less controllable energy sources, like wind and solar, into the generation mix which helps lower our carbon footprint and the importation of diesel fuel.

Right-sizing energy storage depends on a host of factors: generator sizes, load profiles, resource availability, cost of systems, and others.  The right size and type of battery for a wind project is generally not the same as that for a solar project.  Solar power production follows a predictable diurnal cycle that, although affected by clouds and other obstructions, can be relied on to calculate how many hours of storage would be beneficial for a given system.  Two solar/battery storage systems are currently installed on AVEC systems.  They are owned and operated by the Tribes in Noatak and Shungnak/Kobuk.

Wind has a more variable production cycle. The wind can blow (or not) for days.  During times of good production any reasonable energy storage battery would be fully charged, and future discharge of a couple hours storage would be less impactful.  AVEC has been concentrating on providing shorter term energy storage to mate with our wind systems to help improve power quality and minimize the capacity and run time of the diesel engines.  Two such energy storage systems are being installed by AVEC this fall in St. Mary’s and Stebbins.

AVEC has been working diligently to make all of our power plants “renewable ready” by upgrading control systems.  Whenever renewable generation systems are being added to our microgrids, AVEC has been working to incorporate energy storage to maximize their benefit.  Diesel generation is not going away anytime soon, but hopefully we can continue to reduce fuel consumption through renewable generation and energy storage.

Until Next Time,

Bill Stamm