By: Peter Asmus
Meeting the demand for electricity in 2020 is a global conundrum. The customer loads served by today’s alternating current (AC) power grid infrastructure built up over the past 100 years are more often than not natively direct current (DC) due to the proliferation of plug loads. These include computers and mobile devices as well as LED lighting and new and more efficient appliances. According to some estimates, as much as 80% of demand for electricity in residential and commercial and structures are natively DC.
There is growing momentum to move toward a new approach to providing energy services in the form of modular microgrids, which offer resiliency in the face of climate change, extreme weather, and wildfires. Combining the economic advantages of DC, which is inherently modular with the islanding capabilities embedded in DC distribution networks, offers the following advantages over traditional AC grid infrastructure:
- Higher overall system efficiency (under most circumstances)
- Interconnection ease of DC generation sources (e.g., solar, wind, and fuel cells)
- Interconnection ease of advanced battery systems
- Elimination of reactive power constraints imposed by an AC architecture
- Elimination of the need to synchronize diverse generation sources to a single AC grid frequency
To date, the idea of DC modular microgrids has been focused on behind-the-meter applications. However, a pilot project that has been successfully islanding and running autonomously for well over 1 month at Kirtland Airforce Base in Albuquerque, New Mexico takes a radically different approach.
First of its Kind New Mexico Project
This DC microgrid is testing out a system designed to serve new residential subdivisions with front-of-the meter assets financed through utility rate-basing while using modular DC networks to reduce cost, boost efficiency, and simplify the resiliency value proposition. These pieces have not been put together in this combination anywhere in the world (see following figure).
Front-of-the-Meter DC Utility Rate-Based Modular Microgrids
The pilot project, developed by Emera Technologies in partnership with Sandia National Laboratories and Helia Technologies is a glimpse into what a future sustainable and resilient power system could look like. The Helia Technologies partnership is an open source microgrid control platform nurtured at the Stone Edge Farm in Sonoma County, California.
History and Future of Emera Technologies
Founded in 1998, Emera, the parent company of Emera Technologies, has grown from a single electric utility in Nova Scotia, Canada, into a major transnational utility with customers and assets in Canada, the US, and the Caribbean. Emera launched Emera Technologies to advance a microgrid value proposition targeting between 50 and 100 homes. The offering is a complete power system solution that integrates generation, storage, cabling, and controls to serve new residential subdivisions. With solar and battery capacity at every home—as well as additional resources at a small energy park, all generation and storage in the neighborhood become shared resources available to every customer. The Emera Technologies system can island indefinitely thanks to its DC configuration, without a grid connection. When grid-connected, it can provide grid services such as excess capacity back to the power grid.
Emera Technologies’ primary business model entails the installation of all facilities in front of the meter. Thus, the entire system can be utility owned, operated, and maintained. This ownership means builders and homeowners are not burdened with upfront capital costs, system maintenance requirements, worries about replacing components, or complexities when selling their home. Utilities can retain customers with a unique form of a utility distribution microgrid and make progress against renewable energy mandates while responding to growing customer interest in distributed energy resource options.
Thomas Edison would love it.