BioCycle Magazine

Symphony Of The Microgrid At An Urban University

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Perched on the wind-sculpted bluffs above the Pacific Ocean, the University of California San Diego (UCSD) is one of the world’s leading research universities, with an average R&D budget of $1 billion in each of the last three years. Research includes over 50 years of investigating climate change at UCSD’s Scripps Institution of Oceanography, making it no surprise that the university operates one of the world’s most advanced, low emission microgrids.

“There is definitely a movement toward microgrids for communities, industries and military bases that are looking to increase three things: reliability, survivability and resiliency when natural or manmade disaster occurs,” says Byron Washom, Director of Strategic Energy for UCSD’s campus. This 42-megawatt microgrid, however, is more than just a backup in case of disaster. It self-generates 92 percent of UCSD’s annual electricity load and 95 percent of its heating and cooling load, which is no mean feat, as UCSD has 11.6 million square feet of buildings. Six million of the total square feet have been added in the last 10 years, an area equal to 60 percent of the Pentagon, Washom adds.

Washom likens the operation of the university’s state-of-the-art microgrid to a symphony, where many instruments must seamlessly integrate a multitude of notes into a beautiful serenade, and where each must know how and when to cede performance to the most optimally placed instrument. “Within microgrid development, gas turbines or fuel cells are an essential cornerstone in order to firm up the generation reliability,” he explains. “And of the two fuel choices for those, natural gas and biofuels, biogas fuel is by far the best environmental choice. [With biogas] you avoid the intermittency issue. You firm up your reliability of supply.”
Directed Biogas

Biogas is a stellar feature of UCSD’s microgrid, and marks a first for the state. The biogas is generated by the Point Loma wastewater treatment plant, conditioned to natural gas pipeline quality and injected into the pipeline as renewable natural gas. The UCSD fuel cell utilizes an equivalent amount of fossil natural gas. This arrangement is referred to as “directed biogas” (see “Directed Biogas To Power Fuel Cells,” June 2011). “The Point Loma wastewater treatment plant was flaring excess methane, so we entered into a partnership and raised funding for a purification plant,” says Washom. “It’s the first time in California someone has taken surplus methane from a wastewater treatment plant and injected it into an SDG&E (San Diego Gas & Electric) pipeline based on industry standards, which I can guarantee were written never to be met. But we did!”

Kenneth Frisbie, managing director of BioFuels Energy LLC, the university’s partner in the project, concurs with Washom that they were the first to meet California’s Rule 30 requirement for purifying waste methane to meet the 990 BTU standard to inject it into a utility pipeline. The Point Loma plant was flaring 1.1 million cubic feet per day.

Frisbie says they use an Air Liquide biogas purification system to comply with Rule 30. In addition to purifying the gas, other requirements for interconnection included a study to determine if the nearest pipeline had enough capacity to take the gas. “We were lucky to be able to interconnect into that pipeline,” says Frisbie. “No capacity increases needed to be done.” It cost $1.6 million to determine that BioFuels could connect to a pipeline situated approximately 1,000 feet from the treatment plant.

Washom acknowledges the pivotal role the university played. “UCSD was the philanthropic agent for the orchestra. Had we not been the financial partner to take the directed biogas, it would not have occurred. Someone could have stepped forward and said if you can purify [the gas] and inject it into the pipeline and get renewable credits, we will be happy to use it in our turbine. But we said, 'Not only do we want the directed biogas, but we want to use it in a fuel cell because a fuel cell converts to electricity without combustion, and gives ultra low emissions.’”

The result: UCSD campus has the world’s largest fuel cell — 2.8 MW — that uses wastewater treatment plant methane. “It’s a swap,” says Washom. “People in Point Loma are locally using our methane, and we’re using their natural gas coming from the north and headed in their direction!”

He notes that the size and efficiency of the fuel cell is stunning. Covering an area the size of a tennis court and combined with an absorption chiller, it will reach 68 percent efficiency (approximately 48% electricity and 20% chilling capacity). “To put that in perspective, our central utility plant, 10 times the size, won an EPA EnergyStar award in 2010 by reaching 66 percent efficiency, and it was only one of three to get the award!,” explains Washom. “We have reduced the size of the power plant by an order of magnitude and simultaneously boosted efficiency into the same stratosphere as the best in class. Very seldom do you reduce something by an order of magnitude in size and still maintain efficiency.” He adds that the pollutants coming out of UCSD’s fuel cell are barely measurable.

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