GRIDsilience & Transformation with Maine’s Electric Utilities

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https://www.youtube.com/watch?v=y55mJhP10Ts&list=PLDRtdrwy0vtUBM8r32NtRTdhLphY74KP9&index=1

“The North American electric grid is the largest and most complicated machine ever built by humanity… and is hidden in plain sight.” 

This is how Versant Power’s David Norman began the second panel at E2Tech’s GRIDsilience event. While Norman focused on the physics and physical management of the grid, Central Maine Power’s Craig Nale talked about the practical business of planning, maintaining and upgrading it. 

(Click here for the first GRIDsilience panel focused on system planning with ISO New England's Melissa Winne, Maine Public Utilities Commission's Phil Bartlett, and Maine Department of Energy Resources' Ethan Tremblay. Click here for slides from the event. You can also register now for a virtual conversation with world-renowned energy systems expert Lorenzo Kristov on August 27 about building a 21st century electricity system that is affordable, equitable, resilient, less environmentally harmful, and centered on the needs and prosperity of local communities.)

The grid can be thought of as an enormous machine that was designed for a world that no longer quite exists. The old system had a certain simple logic. Big generators made electricity. Transmission lines carried it long distances. Distribution lines brought it to homes and businesses. Customers flipped a switch, and electricity came to them.

The grid has evolved into something more distributive, dynamic and democratic. Solar panels are producing power on rooftops and fields. Batteries are storing electricity and releasing it at different times. Heat pumps and electric vehicles are turning customers into larger and more flexible participants in the system. Data centers and other large loads are creating new demands. Storms are testing the physical infrastructure. And all of this is happening on a grid that is expected to perform its original job flawlessly.

Put the two together and you get a picture of an electric system undergoing something deeper than an equipment upgrade. It is becoming a different kind of machine.

Maine is at the Forefront

In many ways, Maine is true to its Dirigo motto of “I lead” when it comes to its electric system. Maine has more watts of distributed solar generation capacity per person than any other state. David Norman cited a recent Institute for Local Self-Reliance study putting Maine at roughly 1,376 watts of distributed solar per person—about twice the level of the next-highest states.

In Versant’s territory, solar connected to the distribution system is roughly equivalent to 107% of peak load. That means Maine is not merely contemplating what a high-solar grid might look like, it is already operating one. While the electric grid was built around the idea that large machines would generate electricity and the grid would carry it outward, now thousands of relatively small devices can generate electricity and push it back into a system that previously was not designed for power to flow in quite so many directions.

Norman illustrated how the electric grid is not just a network of wires. It is a synchronized physical system. From Nova Scotia to Florida and westward beyond the Mississippi, the Eastern Interconnection operates as one enormous machine. Generators are synchronized. When a large industrial motor at a mill starts, power plants hundreds of miles away participate in meeting the sudden demand.

Norman explained that the system has inertia and inertia matters. A conventional power plant may have several tons of steel spinning thousands of times a minute. That rotating mass provides a stabilizing force. It is an almost invisible reserve of physical strength built into the traditional grid.

Solar panels don't work that way. They give us electricity through inverters rather than massive rotating machines. And as more solar comes online, conventional generators can shut down during the middle of the day. The result is that the grid can lose some of the physical characteristics that historically helped keep it stable. One solution is to emphasize grid-forming inverters, which can simulate inertia, over grid-following inverters.

Being Proactive About Reactive Power

Norman spent part of his presentation discussing something most electricity consumers have never heard of: reactive power. Reactive power helps establish the voltage and electromagnetic fields that allow the electric system to function. Motors need it. Transmission lines need it. And everyone who buys an appliance has a small influence on it.

A cheap, inefficient motor in a refrigerator, hot tub or pool pump can require more reactive power. A better-designed motor requires less. It is a reminder that the grid is a collective system in a very literal sense.

The individual consumer usually experiences electricity as an invisible commodity. Flip the switch and the light comes on. But underneath that simple transaction is a constantly negotiated physical relationship among millions of generators, machines, wires and customers. As the mix of those machines changes, the rules of operation should and do change too.

Norman said that on a normal day, Versant's northern Maine system can generate enough solar electricity to supply the region's entire demand, with some power exported to Canada because there isn't enough storage to save it for later.

That is an extraordinary achievement from one perspective. It can also be an engineering problem. When conventional generators shut down, the grid loses some of the equipment that naturally provides inertia and reactive power. So Versant has installed three synchronous condensers and a Static Synchronous Compensator (STATCOM), at the direction of ISO New England, to help maintain stability.

A synchronous condenser is essentially a large rotating machine that can provide reactive power and other stabilizing characteristics without actually generating electricity. Norman noted that 27% of New England's synchronous condensers are located in Versant's relatively small territory. The clean energy transition is not simply replacing one machine or generator with another, it can require supporting regulatory and physical architecture.

A Smarter Grid

Craig Nale approached the same transformation from the perspective of the utility’s planning process. Central Maine Power (CMP) operates about 25,000 miles of distribution lines across a territory more than twice the size of Connecticut. Maine being the most heavily forested state makes basic maintenance a challenge even before grid changes.

Nale elaborated on how the system does not have one obvious moment of maximum stress. During a sunny afternoon in rural Maine, electricity demand might be relatively low. People are at work. Heating and cooling loads are modest. The sun is shining. Solar generation is high. Now consider a contrasting scenario of a winter evening in southern York County. People are home. They're cooking. They're doing laundry. Heat pumps are running. The sun has disappeared. Those are almost opposite grid conditions.

In one case, there can be too much generation relative to local demand. In the other, there can be very high demand with little local generation. Both can stress the same infrastructure. That is one reason the old idea of simply planning for "peak demand" is becoming less useful.

Utilities need to know what is happening on the grid in much finer detail and then have the ability to respond. This is where the transformation begins to sound less like traditional utility engineering and more like information technology. We need to understand not merely how much electricity customers are using, but when and where they are using it, what distributed resources are producing, where voltage problems are developing and how long a particular constraint is likely to last.

That information could change the economics of grid construction. Instead of building a permanent piece of infrastructure to solve a problem that occurs for only a few hours a year, a utility might use a battery to address the constraint. Nale described the possibility of time-series planning, in which utilities examine not simply the annual peak but the timing and duration of particular system stresses. In some cases, he said, a mobile battery could even be moved to the location where it is needed.

Storage is obviously important to the future of the grid. A battery can absorb excess solar power during the middle of the day and release it when demand rises later. But Norman offered an important qualification, a battery is only useful to the grid if the system can depend on what the battery will do. It needs to charge when it is supposed to charge. It needs to discharge when it is supposed to discharge. It needs to maintain enough capacity to respond when the grid needs it.

“The orchestra needs a conductor,” Norman said.

The clean energy transition with solar panels and batteries has made tremendous progress, the next challenge is coordinating all the pieces so they behave as an integrated system. There is a tendency to talk about the energy transition as if it were primarily a contest between technologies. Solar versus natural gas. Batteries versus generators. Electric vehicles versus gasoline cars. But Nale and Norman's presentations suggest something more fundamental is happening.

One reason the grid is becoming more complicated is because the relationship between producers and consumers is changing. The old system was comparatively hierarchical, electricity flowed from a relatively small number of large generators toward a large number of customers.

The emerging system has electricity coming from many directions and being consumed in many different ways. Customers can generate power. Heat pumps can become significant loads. Electric vehicles can potentially become flexible resources. Batteries can consume and produce power. Large customers may be able to adjust their consumption.

Both Norman and Nale were ultimately talking about the same thing: how to keep an enormously complicated machine working while almost everything about the way it operates is evolving. That is what grid transformation means. Not simply building a cleaner grid, but building a grid smart enough, flexible enough and resilient enough to handle the energy we need and the world that is coming. A better world needs a better grid.

Special thanks to event sponsors ⁠The Roux Institute⁠⁠⁠ at Northeastern University, ⁠Central Maine Power⁠, ⁠Cianbro⁠, and ⁠Drummond Woodsum⁠. E2Tech programs are supported by our members and sustaining partners like the Maine Technology Institute which offers grants, loans, equity investments, and services to foster Maine’s innovation economy.