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Microgrids: the next step in resiliency for Pacific Northwest utilities

From 1980 to 2014, the United States experienced a total of 178 climate or weather-related disasters[1]. Eight of these events have occurred since 2014, and all of them had overall damages exceeding $1B USD per event. With global climate change intensifying and increasing the frequency of major weather disasters, many utilities are considering: how can we capitalize on emerging technologies and sustainable energy resources to increase resiliency, especially for our most vulnerable communities, in the face of disaster?

Microgrids are increasingly being investigated, funded, and deployed to enhance electric system resiliency. But what is a microgrid, and how are they used?

Microgrids are autonomous electric power systems capable of operating independently, or islanded, from the main power grid. Because they can be islanded, microgrids can continue to operate when the main grid under outage, can serve as a resource for faster system response and recovery, and can provide pockets to electric supply during large scale grid failure. During normal grid operation microgrid resources are connected to the utility system providing bill savings to the customer and grid benefits to the utility.

Microgrids can be designed and installed in a variety of sizes and configurations, but many utilities are considering an integrated mix of renewable energy, battery energy storage systems, and fossil generation systems. These systems balance intermittent, carbon-neutral renewable energy with the reliability of energy storage and fossil generation, all dynamically managed by a separate set of controls. When resources are grid connected microgrid control systems manage energy production for grid benefit. During islanded operation, resources are controlled to maximize serving critical facility load. Physically, microgrids could appear to a passerby as a solar PV array on a roof, an enclosed battery system, small diesel generator sited outdoors and controllers inside a building’s electrical room. They can be housed anywhere; on a school, government facility, community center, as a stand-alone facility, or even a home.

In the Pacific Northwest, utilities are typically winter-peaking, meaning that winter snow and ice storms causing multi-day electricity outages coincide with the when customers are most reliant on electric power. A city’s centrally located microgrid (or microgrids) not only provide electric resiliency for the utility, but can serve as an emergency shelter for vulnerable customers, a community rallying point, or an emergency response team’s home base.

The Washington Department of Commerce’s Clean Energy Fund recently awarded $12.6M in 2016, and a further $7M in 2017, to five Washington State-based utilities for grid modernization, including the development of microgrids:

  • Avista of Spokane will pilot a “shared energy economy” model that allows various energy assets — from solar panels and battery storage to traditional utility assets — to be shared for multiple purposes, including system efficiency and grid resiliency. It will demonstrate how the consumer and utility can each benefit.
  • Seattle City Light will create a microgridat a community center, powered by solar energyDuring an outage, this stand-alone power grid will keep the  community centeroperating.
  • Snohomish Public Utility District will combine battery storage, microgrid and solar technologies, connecting this integrated technology to the electric vehicle fleet. It will demonstrate how to leverage batteries in cars to store and use renewable energy.

DNV GL is supporting one of the utilities, Seattle City Light, with site selection and owner’s engineering during the construction of a solar and battery storage microgrid in Seattle, WA.

Microgrids offer benefits in three key areas – reliability, efficiency and sustainability. Microgrids support higher deployment of renewables by smoothing or firming intermittent renewable resources. Microgrids can increase the efficiency of customer sited resources such as combined heat and power systems, building management systems, thus helping the customer realize bill savings through added efficiency. In addition, microgrid resources can provide multiple over-the-meter services to the distribution system or electric market operator.

[1] https://www.energy.gov/sites/prod/files/2016/06/f32/A%20More%20Resilient%20Grid.pdf

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