Microgrids would make it easier to integrate more rooftop solar and other distributed energy resources into the electric grid.
By Jane Twitmyer
Building a clean electric system takes more than switching from fossil fuels to renewables. To make good use of wind and solar power, Virginia needs a modern, flexible electric grid that can exploit and optimize the unique attributes those resources bring to bear. And it needs new rules — laws and regulations — that can allow such a system to develop.
A more flexible electric system will be built in part around microgrids. The Navigant consulting firm defines microgrids as networks incorporating a variety of distributed energy resources, such as wind and solar, that can be aggregated, can balance loads and generation with or without energy storage, and can function whether connected or not to a traditional utility power grid.
As distributed renewable energy resources replace large central generation plants — more rooftop solar, more community wind and solar — electricity generation becomes more localized. Localized generators, particularly photovoltaic solar, require less supporting infrastructure. For instance, local generation doesn’t require transmission lines to wheel electricity across long distances (leaking electricity in the process). And unlike natural gas, it doesn’t require pipelines to deliver fuel to the generating site.
The traditional grid was built to send electricity from a large central plant to all consumers in a large, interconnected area. Locally generated electricity has additional abilities. It can be owned by the customer or by a third party. It can be aggregated, often by a utility, and it can even feed excess generation into the central grid if properly integrated with the central grid.
Full integration will require a structure capable of exploiting these capabilities. It also requires a distributed energy resource (DER) management system, able to control both the DER and the traditional grid.
While most of today’s installed new resources are connected to the grid and can draw electricity from the grid when they need to, most distributed resources are not truly integrated into grid operations.
The military took the first stab at building a local, self-contained system, tied to the central grid but capable of separating and operating on its own for a reasonable amount of time. Their original purpose was base security. For many years the military had relied on small, isolated, self-contained grids in remote locations. In the mid 2000’s they began to look at ensuring power at bases stays on, especially in mission-critical operations. The modern microgrid fit their requirements.
A current test bed is Otis Air Force Base on Cape Cod, Mass., where the plan is for the base to be electrically self-sufficient with all of the power coming from renewable resources.
Microgrids also are being developed at universities. Princeton University, showcased how microgrid technology kept power on when the central grid failed during Hurricane Sandy.
Communities are also creating microgrids for critical facilities in hurricane zones, and utilities are building microgrids to postpone expensive expansions. The Brooklyn Microgrid connected a network of building owners who own solar arrays with their neighbors who want to be buyers of solar electricity. The microgrid replaced the utility’s need to build a $1 billion substation.
In 2018 Illinois regulators approved Commonwealth Edison’s microgrid cluster in Chicago. The $25 million project is the first “utility-scale microgrid cluster. Two microgrids that interact with each other will directly serve more than 1,000 residential, commercial, and small industrial customers in the South Side of Chicago.”
Finally, data centers, so integral to Virginia’s future energy profile, are moving away from direct ownership of hard assets and mitigating downtime risks through options like advanced microgrids. Grid downtime is extremely expensive, and IT companies are racing to meet their huge electricity needs with 100% renewable energy. They are developing ways to supply multiple locations with advanced microgrid technology, essentially “virtual power plants” able to aggregate disparate, geographically dispersed resources capable of responding to the microgrid’s needs with speed and accuracy.
The key is the ability to interact with and act upon data from many sensors in a way the old grid could not. The new system will rely on software and a smart grid to remotely and automatically dispatch retail DER services to the markets. These digital platforms, made up of a variety of microgrid interconnections, can also perform valuable grid functions. Employing them will make the highest and best use of the operational qualities of our new resources.
Here in Virginia a good place to start would be to develop microgrids for essential facilities, especially along the coast. Microgrids will improve system reliability, maintain crucial services during a grid outage, and speed up the return of service to the full grid. The microgrid approach could possibly replace a lot of proposed transmission line fixes, and be even more effective.
Jane Twitmyer, a renewable energy advocate and former consultant, lives in the Blue Ridge Mountains.
