The concept of a decentralized, stand-alone microgrid has long been viewed as the stuff of science fiction, so it may come as a surprise to many that U.S. military bases, college campuses and utilities are already moving forward with pilot projects and research designed to prove that microgrids are not only feasible, but they're a boon to system reliability.
San Diego Gas & Electric's Borrego Springs project is one example. In another, AEP's hosting, for more than a decade, of the Consortium for Electric Reliability Solutions (CERTS) test site (see "Not Just Any Microgrid") has allowed for key breakthroughs in potential microgrid commercialization.
The Sacramento Municipal Utility District (SMUD) has taken the CERTS research out of the laboratory and into the real world with its headquarters-based microgrid (download the SMUD project pdf here) that includes three 100 kW CHP combined-heat-and-power natural gas-fired generators, 10-kW of solar PV panels, and a 500-kW battery for storage purposes. The project will test, monitor and refine the electrical integration of micro-generation systems with the larger utility electrical supply systems and other small power sources such as photovoltaic or fuel cells.
|University of San Diego, microgrid|
The state-of-the-art UC-San Diego microgrid has four times the energy density as a typical commercial/ industrial complex. The campus can provide 85% of its own energy needs and the remaining 15% of power provided by SDG&E still allows the facility to rank as the utility’s fourth largest customer. The microgrid is therefore planned to operate in “island” mode for 85% of the time.
Why the microgrid?
There's been lots of exploration at the national level on incorporating computing architectures (data services plus sensors) into the grid system (known under the rubric "the Smart Grid"). Unfortunately, these efforts suffer from the step function problem. This means that the changes contemplated are too expensive and too wrenching to accomplish on a large scale (akin to boiling the ocean). The only way to implement these new technologies and methods is to find a way to do it organically. The Microgrid enables this by creating a local network (electricity plus data services) that can become a platform for the organic growth of a diverse and innovative ecosystem of solutions and providers.
What does a microgrid do?
A Microgrid enables the ability to:
- Disconnect from the regional grid when there is a general
utility failure. This enables a combination of back-up power systems
from third party providers -- everything from flywheels to back-up
generators (very much the same approach that data-centers use).
- Build a local market for power production. Since the
Microgrid buys power in volume from the regional grid, it will likely
get dynamic pricing data (time of day, etc.). This data allows the
Microgrid to offer local producers of electricity the ability to sell to the Microgrid at competitive prices (peer to peer production). Of
course, if local power production is a priority, then the price
comparison can be weighted via subsidies to favor local producers.
- Add smart features that will only get nominal deployment on the national grid. For example, the ability to add smarts to devices and homes to allow customers to manage their consumption of electricity at a granular level -- from price to device.
According to the author of "Integrating distributed generation into electric power systems", Pecas Lopes, the architecture of our utility system is undergoing historic change. "The power system architecture of the future will look very different from that of today," he and his colleagues wrote. "Whilst the pace of change is likely to be evolutionary, the change itself is expected to be nothing short of a revolution as many traditionally held views and approaches to system operation and planning developed over the past 100 years are challenged and transformed to suit the requirements envisaged in the brave new world of the future."
More news and information on microgrids:
Consortium for Electric Reliability Technology Solutions (CERTS) Microgrid Concept Explained.
Siemens Microgrid White Paper
New Scientist: Virtual power plants could tame coming grid chaos
CleanTechies: Virtual Power Plants: Which Heavyweights Should Investors Bet On? (Siemens, Schneider Electric, and Cisco)
Much of the information for this post comes from Kate Rolin's article, Enabling distributed generation, published for Intelligentutility.