What’s In a Word – A Microgrid or a Managed Grid?

Published: Mon 16 Dec 2013
A blog entry by Christine Hertzog

Contributed by:

Christine Hertzog
Managing Director
Smart Grid Library

Christine Hertzog's Blog

College campuses are often identified as excellent candidates for microgrid deployments, and indeed, many have had them for years, without calling them microgrids.  They had local generation, traditionally in the form of CHP (Combined Heat and Power) for thermal loads e.g. swimming pools and district steam, and as the cost of solar photovoltaic energy has dropped, significant installations of onsite solar PV.  Many have building energy management systems to provide visibility into specific operations such as HVAC (Heating, Ventilation, Air Conditioning), and then added lighting management, occupancy sensors, and other technologies to manage and reduce overall electricity use.

The Smart Grid has introduced new technologies – notably small-scale renewables, energy storage, and more sophisticated solutions that leverage sensors like smart meters to analyze more data.  Foothill College in Los Altos, California, is one academic institution that is literally turning its entire campus into a learning laboratory to explore energy generation, distribution, and new electricity models.  Robert Cormia, an engineering faculty member at Foothill, is one of the contributors to the school’s Integrated Demand Side Management (IDSM) energy strategy.

Bob makes a distinction between a microgrid and a managed grid.  As the author of the Smart Grid Dictionary, I always appreciate careful attention to words and their meanings.  In his view, a microgrid is a system designed for intentional islanding that achieves complete self-sufficiency in energy production.  It must be competently managed in both power systems and energy demand.  A managed grid, which Foothill College has, is one that manages the flows of energy from multiple generation sources and the shapes of power demand.

Microgrids and managed grids share a common technical foundation.  Both are ‘system nodes’ embedded in the greater utility grid. Both deploy a variety of technologies for generation, energy storage, and energy consumption management.  It’s really the objectives of the investments in technologies that distinguish the two.  Foothill-De Anza College District (FHDA) invested in their managed energy grid to reduce their electricity bill and carbon emissions.  However, they don’t intend to make all their own energy, and maintain a connection to the local utility for guaranteed electricity and power (quality) regulation. Their intermediate goal is to supply 50% of their electricity through renewables on their campus.  Right now, they have 1.5 MW of solar PV in parking lots and 250 KW CHP in the form of natural gas fired microturbines that heats their pool.  Bob noted, “When you self-generate, you have to constantly manage voltage, frequency, and phase.”  Not every entity has the resources to do that, although Foothill’s system has been learning by doing.  Bob said one of the big eye-opening discoveries for the college was measuring just how much energy it took to keep their Olympic-sized pool heated.  He summarized the lesson by saying, “no college should have an Olympic sized pool without co-generation.”

In many ways, Foothill College’s managed grid is on the same evolutionary path as the larger grid.  The school knows how much electricity it is producing.  It knows how much energy is consumed by a few large loads.  But it doesn’t always know when, where, and how energy is consumed – buildings still are somewhat unknown entities in terms of their individual consumption profiles and patterns.  At Foothill, they don’t yet have meters on each building, which would be one way to actively monitor, model and manage energy use.  They also don’t have a central application that manages or coordinates their grid as a whole, which will be needed in the future. Their IDSM plan requires an intelligent management solution to deliver the agility to holistically shift and shape demand to take full advantage of their “homegrown” power, while interacting with the utility grid for power quality and demand response.  It’s a need out there that is not being addressed with a bevy of competitive, innovative, and commercialized solutions.  However, Foothill is well on the way to schooling a new generation of entrepreneurs with first-hand appreciation for what managed grids and microgrids can do, and providing a living laboratory for science and engineering students to explore real electric power systems.

Christine Hertzog
Smart Grid Library