Carolina’s most visible commitment to efficiency is at the University’s 32-MW cogeneration plant. This combined heat and power system is used primarily to produce steam, which is piped to 175 campus buildings, including UNC Hospitals, for heating, humidification, hot water heating, sterilization, and making distilled water in laboratories. This steam is also used to generate electricity, with the capacity to meet one-third of the University’s peak demand. This dual function results in an overall efficiency that is twice that of any plant built solely for the purpose of power generation. The cogeneration plant has won multiple awards for cleanliness and efficiency from the U.S. Environmental Protection Agency. In 2008, the EPA recognized UNC for reducing greenhouse gas emissions equivalent to taking 9,011 passenger vehicles off the road. In 2009, the University developed a Climate Action Plan (CAP), which sets attainable and measurable goals to reach climate neutrality by 2050.
Currently the plant is fueled primarily by coal. UNC purchases coal from mines that do not practice mountain-top removal, a mining practice that can irreparably harm local ecosystems. Within the plant, emissions of sulfur dioxide and nitrogen oxide are reduced by generating steam in circulating fluidized bed boilers. Sulfur dioxide is reduced by adding calcium-containing products, such as limestone, to the combustion chamber. Nitrogen oxide production is minimized by keeping the combustion temperature much lower than conventional fossil fuel combustion temperatures, 1,600° F versus more than 2,200° F.
In 2010, Chancellor Holden Thorp commissioned an Energy Task Force to study energy issues on campus. The chancellor accepted all of the group’s recommendations, which included:
- End all use of coal on campus by May 1, 2020;
- Accelerate conversion from coal to a cleaner fuel or fuel mix;
- Source biomass, if used, from certified “sustainably managed” forests, as determined by third-party verification;
- Make best efforts to identify and secure coal that is certified by a third party and sourced from deep mines only;
- Optimize use of natural gas as supplies and costs warrant; and Undertake periodic reviews of the potential for solar thermal and solar photovoltaic system installations.
The first tests in moving from coal to biomass fuels at the cogeneration plant have already taken place. A 20% mix of pelletized & torrefied wood was used in successful pilot burns in fall 2010 and spring 2011.
Cooling the campus is the job of five networked chiller plants. These plants use a combination of electric centrifugal and steam absorption chillers to cool water, which is then pumped to 166 buildings. Two satellite campuses are also served by district chilled water systems. A 5-million gallon thermal energy storage system shifts a portion of the University’s chilled water production to off-peak periods. Electric cost savings range from $108,000 to $459,000 annually, depending on the peak and off-peak electric rates charged by Duke Energy.
In fall 2011, Student Government requested that UNC allocate some of its money into a Green Revolving Fund, which provides low-interest loans to energy conservation, efficiency, and production projects around campus. Chancellor Thorp congratulated the students' innovative thinking and allocated $500,000 to the fund in fall 2011.
UNC Energy Services - http://www.energy.unc.edu/