Stanford University recently announced that it is converting to a new, state-of-the-art energy system that will provide the majority of campus electricity from renewable sources within California.

The Stanford Solar Generating Station, to be designed and built by San Jose-based SunPower, is expected to provide half of all campus electricity. Combined with planned solar power from installations on campus rooftops and the purchase of further renewable power from the grid, renewable energy will supply 65 percent of all campus electricity.

The renewable energy is joined by a first-of-its-kind campus heat recovery system, which began operating March 24 to heat and cool campus buildings.

The school says that the new, estimated $438-million combined system – Stanford Energy System Innovations (SESI) – makes it one of the most energy-efficient research universities in the world. Officials add that the SESI project cuts greenhouse gas emissions by 68 percent CO2 annually and will save Stanford $420 million over 35 years (as compared to a cogeneration option) and will reduce total campus water use by about 15 percent.

Stanford entered into an agreement with SunPower to build a 68-megawatt peak solar plant on approximately 300 acres in California. The Stanford Solar Generating Station will be composed of more than 150,000 high-efficiency SunPower solar panels. The new solar farm is expected to come online in late 2016.

In addition to the solar farm, SunPower was hired by Stanford to install about 5 megawatts of rooftop solar systems on campus. Together with the Stanford Solar plant, the solar systems will provide about 53 percent of Stanford's total electricity use. The remaining 47 percent of Stanford's electricity will come from California grid power, resulting in another 12 percent of which is renewable.

Because about one-fourth of California grid power is renewable (and that will increase to 33 percent by 2020 under state regulations), Stanford's total power mix will provide at least 65 percent clean electricity to campus buildings.

Stanford will use the green electricity produced at both the Stanford solar plant and from installations on campus rooftops, along with the California energy grid, to power campus buildings and the new facility.

Another major part of the the school's new energy system in the on-campus Central Energy Facility (CEF) that relies on a heat-recovery process that is 70 percent more efficient than the 28-yr-old cogeneration process Stanford has been using. Project officials say the CEF will meet more than 90 percent of campus heating demands by capturing almost two-thirds of the waste heat generated by the campus cooling system to produce hot water for the heating system. To make that exchange possible, Stanford has replaced 22 miles of underground pipes and retrofitted 155 buildings to convert the campus from a steam- to hot-water-based system.

"By significantly reducing natural gas usage and electrifying the campus heating and cooling system, we enabled the university's energy supply to be substantially transitioned from fossil fuels with volatile and unpredictable long-term prices to clean renewable electricity sources with affordable costs fixed for a very long time," said Joseph Stagner, executive director of Sustainability and Energy Management at Stanford, in a recent press release.

Key partners in building the SESI plant include Whiting-Turner as contractor; the San Francisco office of Affiliated Engineers Inc.; Portland, OR-based ZGF Architects; Milwaukee, WI-based Johnson Controls Inc.; and Washington, D.C-based Siemens.

SESI began supplying campus energy on March 24, simultaneously with the decommissioning of the 30-year-old, natural-gas cogeneration plant, which supplied virtually all of the university's needs.