Greenhouse Gas Emissions Inventory of the Centalized Renewable Energy System (CRES) at Nebraska Innovation Campus

AUTHORS 3 The Centralized Renewable Energy System (CRES) at Nebraska Innovation Campus (NIC) is a heat-exchanger system that utilizes reclaimed, non-drinkable water from the nearby water treatment plant to heat and cool a projected 1.675 million square feet of office and lab space. A greenhouse gas emissions inventory was estimated for the CRES operating at full build-out of the campus in 2035, compared to conventional office space, being a control system with standard chiller and boiler configuration. The control system is estimated to emit 30,787 metric tons of carbon dioxide-equivalent per year (Mg CO2e yr-1), whereas heating and cooling Nebraska Innovation Campus supplemented by CRES is estimated to emit only 15,637 Mg CO2e yr-1 from electricity use for chillers and pumps, roughly 49% less greenhouse gas emissions compared to the control system, at a savings of roughly 9 kilograms of CO2e per year per square foot. ABSTRACT 4 Nebraska Innovation Campus (NIC) is a research campus designed to facilitate new and in-depth partnerships between the University of Nebraska-Lincoln (UNL) and private sector businesses. By connecting the talents of experts, companies, and the university, NIC creates a unique culture of innovation. NIC is adjacent to UNL and strategically provides access to research faculty, facilities, and students. The campus employs the newest and most creative technologies for heating and cooling. The Centralized Renewable Energy System (CRES) uses reclaimed, non-drinkable water from the nearby water treatment plant to heat and cool the 1.675 million square feet of offices and labs at NIC. The award winning closed-loop system transfers thermal energy in underground piping to the entire NIC campus. This system is more efficient than a geothermal system because of the consistent water temperatures provided by Lincoln's wastewater treatment facility. Today, there are less than a dozen similar projects in the U.S., where CRES will be one of the largest and most unique among the similar facilities. Water temperatures from the water treatment plant range from roughly 57 to 75°F and are expected to have flow rates of 16.5 million gallons per day (MGD) in the winter and 10.4 MGD in the summer. At these temperatures, buildings will be able to utilize heat-exchanger and pump configurations that can operate with a 25% energy savings in the summer cooling months (Olsson Associates 2013); in the summer, the heat sink is the water treatment effluent as opposed to air cooling or cooling tower, but electricity is …