Accelerating a transition from fossil fuel-based energy sources to renewables is a key component of the university’s sustainability and climate action goals. Thanks to the efforts of the Stanford Energy Systems Innovation (SESI) program, Stanford achieved 100% renewable electricity in the spring of 2022 after its second solar generating station went online. This transformative energy system led to an 80% reduction in greenhouse gas emissions, three years in advance of the target set in the university's long-range planning process.
The 14 sites of rooftop solar panel technology across Stanford generate 4.5 megawatt alternating current (MWac) of solar energy that feed directly into campus operations. These arrays were purposefully selected from over 60 possible campus locations based on factors such as impact on historic buildings, orientation, roof size, and construction impacts.
Stanford’s commitment to renewable energy is also supporting California’s solar energy market. The university has partnered with photovoltaic (PV) energy companies to create long-term power purchase agreements (*PPAs), which led to the construction of the Stanford Solar Generating Station #1 in 2016 and the Stanford Solar Generating Station #2 in 2022.
*A PPA is when a developer installs and operates a solar energy grid and then sells the power generated back to the customer at a fixed price, allowing organizations like Stanford to receive renewable energy and pricing stability without needing to actively manage facilities.
Located in Southern California, the 2016 solar generating station is a 54-MWac facility utilizing single-axis tracking technology, a system where panels tilt on one axis to follow the sun’s movement throughout the day for maximum energy production. The 2022 solar generating station, a 63-MWac facility located in Central California, features an innovative 50-MW lithium-ion battery. This battery can store an estimated 200 megawatt hours (MWh) of solar power, ensuring that consumers receive renewable electricity not only when the sun is shining, but 24 hours a day and seven days a week.
The addition of the second solar generating station brought the university’s renewable capacity to over 120% of its annual electricity consumption, generating an abundance of about 340,000 MWh annually. The university is then able to contribute the excess of the university’s annual electricity consumption from these two facilities through Renewable Energy Certificates (RECs), contributing to a greener California electric grid.
Because of Stanford’s renewable electricity contracts, the university is able to use RECs to help achieve its renewable electricity targets while stabilizing its electricity costs. One REC represents 1-MWh of electricity generation, and serves as a way to distinguish ownership of the environmental benefits of renewable energy production. Since physical electricity is often distributed on a shared grid, it becomes impossible to trace exactly from where one’s electricity is sourced. RECs allow individuals and organizations to track their generation of renewable power, even if that power was funneled into a shared energy system.
Trading RECs helps organizations ensure the financial stability of investment in renewable electricity. In Stanford’s case, the contracted solar PPAs exceed the equivalent of the institution’s annual electricity consumption. Stanford may opt to redistribute those RECs in the market so that others can acquire them to meet their own renewable electricity needs. Inversely, the institution could acquire more RECs to help meet its renewable electricity commitment in the future.
