The University is working steadily to decrease its carbon footprint and move away from using coal.
Campus administrators continually look for ways to reduce overall energy consumption and increase the use of renewable energy while lowering greenhouse gas emissions. It’s part of the University’s concerted effort to get to zero through the Three Zeros Environmental Initiative: net zero water usage; zero waste to landfills; and net zero greenhouse gas emissions.
Since 2007, campus greenhouse gas emissions have been reduced by 19 percent, even as the number of campus buildings has expanded dramatically. A project now underway at the Cogeneration Facility will take those emissions even lower.
The facility’s burners are being restored so the plant can maintain fuel flexibility while doubling the amount of natural gas burned. Construction is expected to be complete by the end of this year, allowing the use of natural gas to increase from 25 percent to 50 percent in 2020. As a result, coal use will significantly decrease, and campus greenhouse gas emissions will be reduced by roughly 5 percent.
“We are constantly moving toward more renewable energy sources, and the foundation of our strategy is maintaining the flexibility to efficiently burn solid, liquid and gaseous fuels,” said Lew Kellogg, executive director of Energy Services, which includes Three Zeros.
When the Cogeneration Facility’s boilers were installed in the late 1980s, coal was far less expensive and more reliable than natural gas, so the plant was configured to burn more coal than gas. Today, as the University moves to stop using coal, and until a practical, affordable and reliable renewable fuel option is available, the Energy Star-rated plant needs to be able to burn much more natural gas, Kellogg said.
Although natural gas is a fossil fuel, Environmental Protection Agency comparisons show that it releases about half the carbon emissions during combustion coal does. Many scientists consider natural gas to be a viable transition to more carbon-neutral forms of energy.
“We want to burn the fuel we use as efficiently as possible so we can maximize the energy produced and minimize any waste,” Kellogg said. “Because the boilers have a good 15 years of life left, it makes sense to engineer them so they can burn more natural gas today without giving up the flexibility to switch between solid, liquid and gaseous forms of renewable fuels as they become available in the future.”
The burner project is an investment in the future. Whereas most facilities that make this kind of change are at the end of their lives, the University facility will be viable – and adaptable – for years to come, said Adam Long, the University’s greenhouse gas specialist.
Even before the restoration project began, the University had cut its coal use in half over the last two decades, from as much as 140,000 tons a year to 70,000 tons a year. “And we actually cut 40,000 tons of that in the best way possible: reducing the need for any fuel through energy efficiency and system optimization,” said Bill Lowery, manager of the Cogeneration Systems.
During the massive campus construction effort that began in the early 2000s, much of the 100-year-old infrastructure that delivered steam to the University and UNC Hospitals was upgraded, Lowery said. “With construction for so many new and renovated buildings underway, we were able to replace or rebuild around 40 percent of the steam distribution system with upgraded, more efficient components.”
Although the campus grew from 10 million square feet to its current 22 million square feet, the upgraded piping system nearly cut in half the thermal losses in the underground network, resulting in annual savings of more than $1 million in fuel costs, he said. Like any change made to the University’s energy systems, this upgrade was designed to pay environmental and economic dividends well into the future.
Cogeneration, which means producing two useful energy forms in one process, yields twice the efficiency a normal power plant does, Lowery explained. At Carolina, steam and electricity are produced, both of which are used to heat, cool and power over 200 buildings for the University and UNC Hospitals, including operating sterilization equipment and making distilled water for laboratories and the hospital.
“We want to burn the fuel we use as efficiently as possible so we can maximize the energy produced and minimize any waste.”
Seventy percent of the energy taken from the fuel sources leaves the Cogeneration Facility as useful energy, Lowery said, whereas a traditional power plant located miles away would yield only a fraction of that efficiency. That’s largely because nearly all the steam generated on campus is used, whereas a traditional power plant condenses unused steam back into water and boils it again, losing two-thirds of the energy.
“Our ability to use four different fuels – coal, natural gas, wood and fuel oil – is exceptional because it gives us incredible resilience,” Kellogg said. “With a Level 1 trauma center at the hospital, more than $1 billion in sponsored research at UNC and the complex needs of 50,000-plus people at a time on campus, we have a lot riding on keeping things up and running.”
To maintain that operational level, campus administrators constantly look toward the future. Evaluating the best mix of fuel sources used to meet the energy needs of a multi-faceted university requires balancing sustainability, economy and efficiency, Kellogg explained.
In addition to incorporating solar energy where feasible, his division is examining economical ways to transport, store and use energy-efficient biofuels and ways the existing fuel-handling systems can be adapted for other fuels.
“We are always looking for better, more sustainable ways to do things,” he said. “We examine every issue in terms of the big picture for the University and how to achieve its goals.”
The burner restoration project is a next step. What began as a measure to lower costs and reduce the University’s carbon footprint in the near term has the possibility to do even more in the long term, Lowery said.
“We know we are going to approach 50 percent gas use in the first year of operation, and our math says we should ultimately be able to do more,” he said. “Our testing will answer many questions so we can take the next logical steps toward reducing both carbon and cost as we prepare for the transition to alternate fuels as they become available.”
— Patty Courtright