Some people are born scientists: when they were lying on the backseat of the station wagon on family trips, gazing up at the rhythmic rise and dip of the overhead wires, they wanted to know how they worked, what they were for, where they were going.  Others are born to be English majors: they used such opportunities to recite a nursery rhyme or go to sleep, only developing a bit of curiosity somewhere in middle age.

Conversations between the two types (English major and scientist) at the latter stages of life might ensue, and the English major might actually learn something useful.

English Major: (petulantly) Why do I need to know about the grid again?  Scientist: Energy is everything, absolutely everything we do, buy, use, eat, wear, watch, drive, Everything.  And if we want to reduce our CO2 output to levels necessary to lessen the chances of climate catastrophe, we will have to change a number of ways we use energy.  This will involve electrification of tasks that currently use fossil fuels, like transportation and home heating.  And unless we all get mini-nuclear reactors installed in our cellars, for this to happen the electric grid will have to become significantly more robust than it is today. This will take major investment and probably a lot of new infrastructure. So step one is, appreciate the grid and our dependence on it.

E: (with resignation) OK, fine, what is the grid? Isn’t it  basically a bunch of overhead wires, poles, occasional tangles of metal, tall and short towers, DANGER signs?  S: Well, a slightly more informed description might be “a very complex interconnection of electricity-generating facilities, high voltage transmission lines, substations, lower voltage distribution lines and connections to homes, businesses, and industries.”

The grid is kind of like the internet in that it spans the globe, but it is also regional and operates in specific parameters in different places.  The grid in the U.S. is divided into wide area “synchronous” grids (meaning the frequencies of the AC power from all suppliers are in phase with one another, which– never mind–Take Physics). Maine is part of a synchronous grid that covers New York, NewEngland and much of eastern Canada.

E: (suddenly alert) Cool, “synchronicity!”  But that’s, um, what again? S: A synchronous grid allows a large number of generators to feed into the system. The power can be distributed more readily and the system can adapt quickly to changes in demand, so that when there is a large change in load, the load gets distributed automatically to the many generating sources on the grid. There are very few reasonable options for storage of electrical energy as of yet, so supply and demand have to be almost exactly balanced at all times.

Synchronous grids can be interconnected to one other with high voltage DC (HVDC) lines capable of sending power over long distances with much lower losses than the high voltage AC lines.  So if one regional grid has considerable excess power it can send it to another over these lines.

E: (mind wandering) So if Connecticut commissions a solar farm in Maine will it be sending that power all the way to Connecticut?  S: No. In actuality there is no way to know precisely where the energy lighting your kitchen is coming from. It’s like a reservoir where a supplier puts water into the reservoir at one location and the user takes water at another location.  The molecules of water that the user gets are not the same as the molecules that the supplier puts out. Such a system would be very inefficient and require a ridiculous tangle of individual wires.

So the energy from the big solar farm in Maine will primarily get used in Maine while other suppliers will be providing the energy that Connecticut is buying. This is actually one of the main reasons for the existence of the grid.

E: What is a microgrid? (sounds sort of cute!)  S: A microgrid is generally defined as a self-sufficient energy system serving a small area and usually connected synchronously to the wide area grid.  It has its own suppliers of power (solar, wind, co-generation, etc.) and is able to operate independently of the larger grid if necessary, but again, limitations in storage create limitations in the balancing of supply with demand.  I don’t know, is that cute?

E: (emboldened) OK, what is a “smart” grid? S: The smart grid is the future, and a future column, too.

Well, that’s actually a relief – but, speaking of smart, don’t we English majors feel just a wee bit more grown up now?  It’s never too late, they say…

Paul Stancioff, PhD., is a professor of Physics at the University of Maine Farmington who studies energy economics on the side.  He can be reached at pauls@maine.edu.  Cynthia Stancioff is an amateur naturalist who likes to write. Previous columns can be found at https://paulandcynthiaenergymatters.blogspot.com/.

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