Why colleges are big believers in microgrids

We tend to think of colleges, and especially students, as our future -- not only the students themselves, the next generation of leaders, but the actual campuses, from which we can learn about our electricity future.

While most of the U.S. still relies on large-scale centralized electrical generation and long-distance transmission, university campuses are one U.S. sector that has embraced microgrid technology.

Rocky Mountain Institute recently explored why microgrids have been so readily adopted on college campuses. Many of these institutions have four underlying factors in common: district-scale central thermal plants and distribution, sole ownership, high reliability needs and a long investment horizon.

Here is a look at each factor that has driven colleges' adoption of microgrids.

Central thermal plants: More than a century of district heating

Universities have led microgrid development since the 1890s. More than a century ago, many universities heated their campuses with district heating from a local central thermal plant. This approach efficiently heats a cluster of buildings, avoiding the need for individual boilers or furnaces in each building. Those central thermal plants provided the launch pad for university microgrids.

As technology improved, many universities converted their original central thermal plants to combined heat and power (CHP) plants, enabling electricity generation as well as district heating or cooling. These CHP plants reliably can generate large amounts of power at system efficiencies as high as 80 percent (PDF), compared to typical utility power plant efficiencies of about 30 percent. In industry parlance, CHP plants are also great base load generators, making it easier to build a microgrid.

This is exactly what happened at Princeton University with its aging boilers during the late 1980s. Princeton's 150 buildings were heated and cooled by a central steam plant and a chilled water plant. The university opted for CHP as a better option. Its cogeneration plant now generates 15 megawatts of electricity, about equal to Princeton's average daily electricity needs. A few years later it added a thermal energy storage system -- a 2.6 million gallon tank of chilled water, which improves the system's efficiency and offers greater operational flexibility.

Ownership: The benefits of being a large landowner

In most of the U.S., electric utilities hold a franchise for the exclusive provision of electricity in a defined community or service territory. Such laws originally were intended to constrain redundant infrastructure and limit monopoly power of the utility, but they also hinder microgrids by obstructing local distributed generators from selling highly reliable power to nearby users if that power has to cross a street or public right of way where the franchise has domain.

But on college or university campuses, a common owner operates, maintains and supplies heating, cooling and electricity to 100 or more buildings. That aggregated scale is ideal for combined heat and power and a district energy network.

For example, the University of California, San Diego -- covering 1,200 acres and with 11 million square feet of buildings -- is like a small city. The university's 30 megawatt microgrid generates more than 90 percent of annual electricity demand. UCSD has only one connection to the local utility grid at the transmission level, and it owns the high-voltage substation. The campus also owns and maintains all of its distribution wires and meters.

Harvard's main campus, in contrast, stretches over 200 acres and comprises hundreds of buildings, many of which are served by the university's microgrid and district heating system. However, the university crosses many public rights of way in two cities and counties. It has been wrestling with the franchise issue as it looks to install additional co-generation and expand its microgrid to a greater portion of the campus.

Reliability: The importance of islanding

In part because of the important research they often support, universities place a premium on reliability. The unparalleled reliability such systems offer is one reason why they often turn to microgrids.

When Superstorm Sandy hit the East Coast, much of Princeton's campus stayed lit while the surrounding city was in the dark. Per Ted Borer, the university's energy plant manager, it was largely business as usual.

"The guys in the plant are just trying to do what they always do, keep the lights on and the engines turning. Now you do that with extra personnel, and a heightened sensitivity, because you no longer have a margin for error," he said. "But otherwise, it's the same thing you do everyday."  

The university designed the microgrid so the campus electrical system could become its own island in an emergency.

"It cost a little more to do that," Borer told us, "but I'm sure glad we did."

Long investment horizon: Keeping an eye toward the future

The final advantage that really tips the microgrid scale for universities is their long investment horizon. Facility managers can consider investments with longer payback periods because they are confident the university still will be operating, in exactly the same location, 30 years down the road.

"Harvard's older than the country," says Bob Manning, director of engineering and utilities at the university. "We certainly expect our systems to be here for a long time."

With that kind of confidence, it's easier for universities to make investments that may take longer than 10 years to pay back.
 
In the late 1920s, for example, the University of Texas at Austin faced the decision whether to add electricity distribution to its district energy system or allow the local electric utility to provide service to the campus. Carl Eckhardt, superintendent of the power plant at the time, wanted to act in the university's best long-term interest. Thus, in 1929, the university installed steam turbine generators to provide campus electricity, a critical first step toward the microgrid it has today.

"We are the beneficiaries of the core infrastructure [Eckhardt] built," said Juan Ontiveros, executive director of utilities at the university.

Leadership and education beyond the classroom

As of this publication, 673 universities are signatories to the American College & University Presidents' Climate Commitment (ACUPCC), a "high-visibility effort to address global climate disruption ... and to promote the research and educational efforts of higher education to equip society to re-stabilize the earth's climate."

The same efficiency gains that make district energy and CHP cost effective also serve to provide a much lower carbon footprint for the institutions that adopt such strategies.
 
Rocky Mountain Institute is partnering with Arizona State University and Ameresco on just such an endeavor. With a goal of carbon neutrality by 2025, ASU knows it has a lot of work to do to get there, and strategies such as microgrids may figure prominently in the equation.

Lessons for the rest of us

Recognizing the four factors that makes microgrids attractive for universities helps identify other facilities that are ripe targets for microgrid investments: large industrial facilities with CHP, established district heating systems that do not yet have CHP, and critical infrastructure, such as hospitals and military installations, for example.

To further expand the microgrid market means reducing or eliminating the barriers for actors that do not have the same investment horizons, reliability needs or property advantage as universities.

This means working with utilities and regulators to revisit franchise laws, and helping technology developers lower the costs of microgrid infrastructure. Unlocking the full potential for microgrids to support an energy infrastructure that is both more reliable and more sustainable will require innovation and collaboration from all the actors in our energy ecosystem.

Harvard sign image by cdrin via Shutterstock.