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A Powerhouse Idea

The new campus energy system promises greatly reduced emissions and costs.

Mark Matcho

It sounded good from the moment it was approved for construction: a new energy plant that would cut carbon emissions by 50 percent, and save Stanford $300 million over the next four decades.

Now, a little less than two and a half years since construction began as part of the Stanford Energy System Innovations project, not only have the initial expectations been justified, they’ve been trumped. Dramatically.

When the new facility begins full function April 1, it’s projected to reduce the university’s greenhouse gas emissions by 80 to 90 percent. And the estimated savings over the next 35 years have increased to $420 million. In addition, the plant features a successfully patented software system that was designed at Stanford to deliver cost efficiency as well as automated control. Even allowing for uncertainty in the final numbers, the scale of accomplishment is notable.

“We’ll only know the exact greenhouse gas reduction we will achieve after the system has been tuned and has performed through different seasons,” said Provost John Etchemendy in an email. “But the estimates do indeed point to a stunning reduction in both our carbon footprint and water usage. And keep in mind that the reduction is from our previous cogeneration system, which was already more environmentally friendly than most campuses in the country.”

The cogeneration plant, commissioned in 1987, relied mostly on natural gas (a fossil fuel) to power a turbine and electrical generator as part of a system that produced steam heat. For the new facility, Stanford will buy clean electricity—solar, wind or geothermal power, for example—from renewable energy markets. Moreover, the process for heating almost the entire campus has now been overhauled for the capture and redistribution of waste heat through a hot water system.

Before the new plant was approved, Joseph Stagner, the executive director of sustainability and energy management, oversaw an analysis showing that more than 80 percent of the university’s heating needs could be supplied with waste heat, which is a plentiful by-product of air conditioning. The current estimate is more than 90 percent.

Using about 20 miles of new underground piping, chilled water will be sent to buildings for cooling needs. Heat that’s being eliminated—the so-called waste heat—will be absorbed by the water and carried through return lines to the energy facility. That heat then can be transferred by industrial machinery to the hot water system, which loops back to the buildings for heating.

Various efficiencies result from this approach, including an almost 20 percent reduction in potable water use and a 70 percent decrease in the amount of unused waste heat vented into the atmosphere through cooling towers. The new heat transfer equipment also is more electrically efficient than the machinery it replaces.

“This energy plant,” says Stagner, “will not only achieve these benefits immediately, but it is designed to allow the university flexibility in its future growth and continue these benefits for the next half century.”

Stagner, a civil engineer, joined Stanford in late 2007 after 14 years as the director of utilities at UC-Davis. Less than a year into his new job, he zeroed in on the waste-heat plan. Then he had to make the case for it—no easy task given that he knew of no precedent for a university-wide hot-water proposal of the same type and magnitude.

It also was Stagner who personally devised the new plant’s automated control system over a year and a half of work on nights and weekends. His software program demonstrated how all the elements of the plant’s design would combine for the desired energy savings, as well as provide an electronic “brain” to monitor operations. Its features include the ability to predict heating, cooling and electricity needs 10 days ahead of time, then determine when it’s most economical to use electricity and how much hot and cold water to store in new thermal tanks.

“There is no question that the SESI project would not have happened without Joe Stagner,” wrote Etchemendy. “Joe was the person who thought out of the box about how we might replace the aging COGEN plant and take Stanford to a completely new level of sustainability. Then, equally important, it was Joe who persisted in the years of analysis and re-analysis that was required to convince the leadership and trustees that the system could really perform as envisioned.”

The new plant is located off Campus Drive near Searsville Road. Some elements of the nearby cogeneration plant, off Campus Drive near Via Ortega, are being sold; what remains will be demolished.

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