October 19, 2009
Stanford moves aggressively to cut energy use, reduce carbon impact
In an effort to tackle the threat of global climate change head on, Stanford University has developed an ambitious, long-range, $250 million initiative to sharply reduce the university's energy consumption and greenhouse gas emissions.
Detailed designs for the plan - drawn up after two years of engineering study - are beginning now.
Changes outlined in the Energy and Climate Plan could reduce the campus carbon impact by as much as 20 percent below 1990 levels by 2020, far exceeding the aggressive goals of California's landmark AB 32 Global Warming Solutions Act.
While the initial phases of the plan rely on aggressive energy conservation and major changes to the campus heating and cooling scheme, even more greenhouse gas reductions may be possible through the use of renewable electricity and other energy management technologies now being explored.
The Energy and Climate Plan, presented to the Stanford Board of Trustees Oct. 12, is one of the most ambitious carbon-reduction programs of major U.S. universities. It includes higher-than-required energy standards for new buildings, major retrofitting of existing buildings, a significant transformation of the campus energy plant, and programs to teach students, faculty and staff how to cut back on their energy use.
"At Stanford, we're taking steps to reduce greenhouse gases through improved efficiency both in consumption and generation of energy," said Stanford President John Hennessy. "Our goal is both to lower our energy costs and to lower our carbon emissions, which is the right step for Stanford and for our planet."
A team of campus faculty and facilities operations experts, headed by Joe Stagner, the university's executive director of the department of sustainability and energy management, worked on the climate and energy plan for two years. After a painstaking study of campus energy use involving hour-by-hour readings for a year, they came to a surprising conclusion.
Unexpectedly, they discovered that over half the university's heating demands could be met with heat that is already being removed from buildings by the campus cooling system. Such a reuse of energy would cut the amount of natural gas burned for heating purposes dramatically, reducing energy costs as well as emissions of greenhouse gases.
Reconfiguring the university's heating and cooling scheme, despite the $250 million price tag, would save money over the next four decades. Energy, water, and other operating cost savings are expected to be about $639 million from 2010 to 2050, after repayment of the initial capital investment.
When discussion of the plan began, "We said, 'We're going to figure out the best business case. It's not going to rely on future technology,' " said Jack Cleary, Stanford's associate vice president for land, buildings and real estate. "This was really taking a look at what the research supports. It's a solution that's based entirely on fact."
Taking a long-term view is key, Stagner said.
The energy-reduction plan revolves around this fact: Campus cooling systems do their job by using chilled water to remove unwanted heat from buildings. For years, that unwanted heat has been piped away from the buildings in the form of warm water, only to be discharged into the air through evaporative cooling towers at the central plant.
But studies by Stagner and his team indicate that if the water were not sent to the cooling towers, 70 percent of that lost heat could be recovered from the water and immediately reused to heat buildings. That's enough spare heat to take care of half of the campus heating needs. The result is that much less natural gas would be burned to warm offices, classrooms, dormitories and laboratories.
Such a system is possible where campus buildings are being cooled and heated at the same time. That's often the case at Stanford, in part because of its mild Mediterranean climate, and also because research facilities make extensive use of refrigeration.
As an additional secondary effect of this "regeneration" project, the elimination of the cooling towers would cut campus water use by about 18 percent, Stagner said.
This simultaneous heating and cooling provides the opportunity for the transfer of excess heat, but capturing and distributing the heat will require construction digging across campus. Most buildings are now heated by steam; for the new system to work, the steam will be replaced with hot water, requiring the replacement of underground pipes over the next five to 10 years.
This conversion from steam to hot water provides another significant opportunity for energy efficiency. Because of the high temperatures and pressures in the steam pipelines coming from the central energy plant, they are expensive to operate and maintain, and allow about 12 percent of the energy to leak out.
Converting the steam distribution system to a hot water system will greatly reduce operating costs and cut energy leaks to less than 4 percent.
Similar conversions are now taking place in many parts of the world for the same reasons, from the city of Munich in Germany to Auburn University in Alabama, providing valuable information to Stanford on the best ways to plan and execute such a major effort.
The project also will bring changes to the university power grid. Stanford's Cardinal Cogeneration plant, which burns natural gas both to create steam heat and generate electricity for the campus, will shut down in a few years under the new energy plan. Instead, electricity will be purchased from PG&E or, if state regulators allow "Direct Access" to reopen, directly from other providers. Direct Access would allow Stanford to control its electricity supply, balancing cost and carbon emission as required to meet university greenhouse gas reduction goals over the long term.
If the university instead purchases its electricity only from PG&E, significant additional greenhouse gas reductions could still be accomplished as PG&E moves to increase the amount of renewable electricity within its portfolio to 33% by 2020, as required by current state law. The cost of green energy, however, and whether it will be supported by government subsidies, remains an issue.
The heat recovery program is an extension of existing Stanford efficiency efforts. New buildings, for example, are constructed to be 30 percent more energy efficient than required by code. The signature building of that endeavor is the Jerry Yang and Akiko Yamazaki Environment and Energy Building, which uses interior atriums to guide hot air up and out, and windows that open at night to let the cool air in.
Much of the carbon reduction envisioned by the Stanford Energy and Climate Plan can be realized in a few years, as soon as the pipes and equipment needed for the hot-water cooling system are installed.
"It will inspire people; it will set an example of what's possible," said Jeff Koseff, co-director of Stanford's Woods Institute for Environment. "I think that's part of the university's mission, to show people the way."