This year’s hurricane and wildfire seasons have once again exposed weaknesses in our electric grid. Distributed energy resources and microgrids—especially solar microgrids—point the way to a better energy future.
Why are power companies so reluctant to move in that direction?
Power companies operate baseline plants that run constantly and supply most of the electricity. At times when demand for electricity exceeds what the baseline plants can supply, the company turns on a plant that usually sits idle until its capacity is needed. In other words, demand peaks, and so the company turns on a peaking plant.
Baseline plants and peaking plants are both located far from the customers that use the electricity. Electricity flows there through high-voltage transmission lines. A step-down transformer reduces the voltage and sends the electricity through distribution lines to end users.
What is the electric grid?
Every power station in the US and Canada is connected to every other station. The system has been called the world’s largest machine. It is divided into three units, or interconnects: the Eastern, Western, and Texas interconnects. Individual power companies have the responsibility for maintaining their part of the grid.
Unlike almost any other product, demand and supply must balance at any given moment. Power companies can’t keep excess power in inventory somewhere.
Thousands of utility companies, most of them operating multiple power plants, cooperate to maintain millions of miles of power lines. They share power among themselves as needed to maintain balance on the grid.
What is distributed energy?
This system has existed for generations, relying on fossil fuels to run the generating plants. The advent of solar and wind power ushered in a new concept: distributed energy. That is, instead of all electricity being generated at a central location, generation is distributed from multiple locations.
Utilities quickly saw distributed energy as threat to their very existence and resisted it at every turn. In recent years, however, some utilities have found ways to use distributed energy to their benefit. Consolidated Edison in New York, for example, pioneered a virtual power plant. It combined 300 rooftop solar systems into a single solar microgrid and integrated it with its system. Power flows from the buildings to the grid or from the grid to the buildings as needed.
What are microgrids?
Microgrids are simply small grids.
Some microgrids are located in areas too remote for major power companies to serve. Individuals or communities who prefer to live off-grid operate others.
Most microgrids are connected to the main grid. In the event of power failure, Many hospitals, businesses, and homes have their own backup generators. Each one operates as a microgrid. They are connected to the grid most of the time but can separate from it at need.
The oldest microgrids have depended on diesel or natural gas generators. Solar microgrids with energy storage offer new flexibility along with not contributing greenhouse gas emissions.
The grid works well most of the time, but it has experienced some spectacular failures. Some have blacked out multiple states for days at a time.
Imagine millions of grid-tied microgrids, say, one for every neighborhood. In event of failure in one, the surrounding ones could cut themselves off and continue to function.
Here are a couple of examples of how it can work:
A California grid in wildfire season
The Marine Corps Air Station at Miramar needs to be able to operate for at least two weeks if the grid fails. And wildfires frequently cause grid failure. So the base operates its own microgrid.
Electricity comes from a combination of solar panels and methane from landfill gas. The microgrid incorporates storage. In the 2020 California heatwave, it generated enough electricity during a blackout that the base could share with the neighboring community.
One bright spot amid Hurricane Ida
Entergy, the power company for New Orleans, commissioned a new peaking plant in 2020. When Hurricane Ida roared ashore in 2021, it failed. Not that it failed to turn on, but it couldn’t provide electricity with all eight of the electric transmission lines down.
Hurricane Katrina in 2005 destroyed 3,000 miles of transmission lines and 30,000 miles of distribution lines. Also, 263 substations failed. Four times as many customers lost power as from any storm before. At the time, distributed energy was only beginning to come to the grid. Smart phones and the Internet of Things didn’t yet exist.
In the years between Katrina and Ida, if Entergy had used these new technologies to develop solar microgrids instead of the peaking plant, New Orleans would have had a faster recovery.
Power came back on quickly at the St. Peter Apartments, though, thanks to its solar microgrid. The 50-unit building has 450 solar panels on the roof. They charge a battery system in the parking lot.
The lights didn’t actually stay on. The battery system suffered damage. Road closures delayed repairs
Once it was fixed, it gave residents almost eight hours of electricity. When the storm passed, the solar panels again generated electricity and recharged the batteries. A cloudy day and heavy demand for air conditioning stretched the system’s capabilities to the limit. With the grid not available, residents had to limit their use of electricity. But they were certainly better off than most of the blacked-out city.
Hurricane Ida was not the first test of the microgrid. The building opened early in 2020. Hurricane Zeta came ashore a few months later, followed by winter storm Uri. In both cases, the system operated as expected.
The key to a resilient electricity supply is not more peaking plants and transmission lines. It is more microgrids that can isolate from the grid and become islands of energy production when storms cripple the grid.
Hurricane Ida teaches New Orleans to value high energy tech and virtual power plants / Ken Silverstein, Forbes. September 5, 2021
In New Orleans, a solar microgrid is keeping lights on in this affordable apartment building / Adele Peters, Fast Company. September 2, 2021