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Sustainable 2nd Century

Sustainable 2nd Century

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  • Climate
  • Renewable Energy at UC Davis

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  • UC Davis West Village tracks its progress toward zero net energy

    UC Davis West Village, the nation’s largest planned zero net energy community, continues to work toward its goal of producing 100 percent of the energy it uses.

  • Biodigester turns campus waste into campus energy

    More than a decade ago, Ruihong Zhang, a professor of biological and agricultural engineering at UC Davis, started working on a problem: How to turn as much organic waste as possible into as much renewable energy as possible. Today, on Earth Day, the university and Sacramento-based technology partner CleanWorld are officially unveiling the UC Davis Renewable Energy Anaerobic Digester (READ) at the campus’ former landfill.

Campus Progress: Renewable Energy at UC Davis

The University of California is pursuing carbon neutrality in a very serious way through our research, teaching, and operations. UC faculty have created a roadmap and the executive summary has been published. A summit to discuss the roadmap was held October 26-27, 2015, at which California Governor Edmund G. (Jerry) Brown, Jr. and UC President Janet Napolitano both discussed their commitments to the UC achieving carbon neutrality and pursuing solutions that can be used globally.

In order to meet our climate neutrality goals, UC Davis actively pursues renewable energy sourcing. Learn more about our projects:

Photo: Aerial photo of large array of solar photovoltaic panels with campus and city of Davis in background

Aerial photo taken of the South Campus Large Solar Power Plant, August 2015, looking northwest with the Davis campus in the background

UC Davis South Campus Large Solar Power Plant

UC Davis has taken a major step forward in securing affordable renewable energy for the campus with the South Campus Large Solar Power Plant. The plant finished construction and began producing electricity in August 2015. This project will help the campus reduce greenhouse gas (GHG) emissions and is part of the path to a carbon neutral future.

Here are some common questions and answers about the project:

Where is the UC Davis solar power plant?

The solar plant is located on the UC Davis campus, on 62 acres south of Interstate 80. The extent of the plant can be seen in the photo above. The campus also has about one megawatt of generating capacity installed elsewhere on campus, including parking lots and rooftops. West Village has about 4 megawatts installed, and operates its own grid with service from Pacific Gas & Electric. UC Davis will continue to look for opportunities to exploit rooftop solar. However, rooftop solar is relatively expensive compared to the large, standalone UC Davis solar plant that is located close to a substation, enabling a fairly simple interconnection to the campus grid.

How much power does the solar plant produce?

The solar plant has a 16.3 megawatt capacity (peak DC) production, making it the nation’s largest “behind-the-meter” solar installation on a university campus. On-site inverters convert that power to AC for delivery to the campus. The AC capacity of the system is 13 megawatts. The system will generate over 33 million kilowatt-hours per year, which is about 14 percent of the campus’s electricity needs. This annual production is expected to reduce the campus’ carbon footprint by about 14,000 metric tons of GHG emissions.

The large solar power plant was sized to be in sync with campus electrical needs. Our contracts with PG&E do not allow the campus to “export” power back into their network if we generate more electricity on site than we need. As a result, all of the power generated by the large solar power plant must be used on-campus. UC Davis supports year-round, energy-intensive research even when school is not in session. Over the course of a year, the minimum electrical demand by the campus is about 19 megawatts. During peak production, campus on-site renewable energy projects generate a maximum of about 14 megawatts of electricity. The 5 MW “buffer” between our minimum use and the maximum on-site production ensures that we never generate more power than we can use.

Track the plant's production in real-time, as well as learn more about the Davis campus energy supplies and uses. The infographic is based on 22 years of energy use and costs, and the real-time displays show total campus energy use, including electricity, natural gas, and on-site renewable generation. In the real-time graphs, viewers can click the various energy sources on and off to see how each contributes to the whole.

How does the solar plant fit with campus sustainability goals?

UC Davis is targeting carbon neutrality (net zero greenhouse gas emissions) for our directly controlled greenhouse gas emissions and our purchased electricity (known respectively as Scope 1 and Scope 2 emissions) by 2025. The Davis campus’s current greenhouse gas emissions are approximately 134,000 metric tons CO2e (total UC Davis emissions are approximately 207,000 metric tons CO2e). This power plant, coupled with other solar photovoltaics on campus, the campus biodigester, and purchases of other solar and hydroelectric power are expected to result in making 60 percent of the campus electricity supply carbon-free.

What about conserving energy instead of building solar power plants?

Both energy efficiency and converting to renewable energy sources are critical to reducing our carbon footprint. UC Davis uses less electricity now than 20 years ago, even though we have grown substantially in population and buildings. But our teaching, research and support activities require energy, so we have to both reduce our demand and "green up" our supply.

How do the solar panels work?

SunPower designed and built the single-axis tracking system. The solar panels are cleaned by a robotic cleaning system that will help maximize energy production and use less water than more traditional panel cleaning methods.

How much did the solar plant cost?

Construction of the plant was implemented using existing funds set aside to pay campus utility bills. It was completed as a public-private partnership with SunPower to reduce campus costs by leveraging the tax incentives available only to private firms.

UC Davis buys the power under a “power purchase agreement” with SunPower. The facility has first year electricity prices of 6.7 cents per kilowatt-hour. By comparison, the average homeowner in the area pays about 20 cents per kilowatt-hour. It is also expected to be less expensive than buying wholesale electricity off of the grid.

The system is anticipated to cost the same as or slightly less than current electricity costs during the first year of operation compared to business as usual. It is cost-effective over the long term. In the 20th year of the contract, the campus will only be paying about 8 cents per kilowatt hour. That is because the contract with SunPower provides predictable pricing for the next 20 years. The price will track projected market rates for the first six years and then become steadily cheaper than the estimated cost of buying electricity on the open market.

How was SunPower selected for the project?

The campus implemented a public procurement process, and SunPower had the lowest net cost among all qualified firms.

Photo: View of tanks and piping at the Davis campus renewable energy anaerobic digester

View of the Renewable Energy Anaerobic Digester, April 2014

Renewable Energy Anaerobic Digester (aka "the biodigester")

In April 2014, UC Davis officially opened the Renewable Energy Anaerobic Digester (READ), a waste-to-energy facility located at the former UC Davis campus landfill. Technology at the facility incorporates inventions resulting from pioneering research on anaerobic digestion by UC Davis Professor Ruihong Zhang and licensed by the University to CleanWorld, a start-up company seeking to bring biodigester technology to a commercial scale. The READ facility was jointly developed by CleanWorld and UC Davis.

At full capacity, the READ facility can handle 50 tons of organic waste per day. A three-stage thermophilic anaerobic digestion system is used with a total working volume of 450,000 gallons. The facility has four California Air Resources Board approved 200 kW microturbines and a 125 kW Rankine-cycle engine-generator for converting waste heat from the microturbines into additional electricity. Approximately 690 kW of the electrical generation capacity is provided by biogas generated at the facility with an additional 235 kW of capacity from landfill gas. The READ facility has been operational since January 2014.  

At full production over 18,000 tons per year of waste will be diverted from local landfills and the UC Davis campus grid will receive approximately 5.6 million kilowatt hours of renewable energy annually.

Photo: Aerial image from Google Earth of buildings and parking lot with solar PV panels on them

Aerial image from Google Earth shows rooftop solar at the Winery, Brewery and Food Science Laboratory and solar panels shading cars at Parking Lot 1.

Rooftop and Parking Lot Solar

In January 2012, the campus "flipped the switch" on solar photovoltaic installations on various central campus building rooftops and a parking lot; the installations total 756 kW of production capacity, or on average 1,290,000 kWh per year. This solar is a power purchase agreement with Mainstreet Power, and is a 20 year contract. Installations are located at the Winery, Brewery and Food Science Laboratory (near the Robert Mondavi Institute), Parking Lot 1, Graduate School of Management and University Conference Center, Tercero Dining Commons, Segundo North (Adler, Miller and Thompson Halls), Segundo Services Center, and Secundo Dining Commons. All of the panel are fixed (no tracking).

In addition, West Village is served by an on-site, 4 MW production capacity, solar system through a power purchase agreement with SunPower. The West Village solar is located on rooftops and parking lots and is also a fixed panel installation.

Sources:

University of California Sustainable Practices Policy

University of California Carbon Neutrality Initiative

UC Davis Large Solar Power Plant, environmental review documents

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