Depending on the season and the airport’s need, DFW heats or cools the glycol at night, taking advantage of off-peak pricing from energy companies. During the peak periods of the day, Crites says that DFW can turn off the chillers and feed off of the super-cooled glycol by pumping it around the building. By doing this, the airport has reduced its peak period demand for energy by 85 percent.
Crites says that DFW has also found success in retro-commissioning buildings. In partnering with the energy systems lab of Texas A&M University — the consulting arm to the Texas Commission on Environmental Quality — the airport has found ways to make existing buildings more efficient. The lab’s findings revealed that due to poor thermostat placement, air handlers were pumping into the wrong areas. Once the building was retro-commissioned, DFW saw a 25-percent reduction in that building’s energy requirement.
DFW is now receiving both environmental and cost benefits with the installation of the largest volume compressed natural gas (CNG) station in the U.S., which feeds the largest fleet of CNG vehicles in the nation. According to Crites, the station — which pumps 150,000-170,000 gallons of CNG a month — is not considered a source of revenue, but rather as a cost offset. Last year, the DFW station pumped 1.3 million gallons of CNG fuel, saving over $2 million had those same vehicles been fueled by gas.
“There’s been a reluctance to take on [new] things just because of the lack of hard data,” says Crites. “Well now that we have measurable results, as we make this information known, the guys who are most excited about sustainable development lately have been the chief financial officers, because they’re starting to see improvement on the bottom lines.”
James Harger, senior vice president, marketing and sales with Clean Energy, a CNG provider, says the biggest reduction in emissions comes with changing a diesel powered vehicle to CNG. “When a diesel bus [averaging 15,000 gallons per year] is taken off the road and a natural gas bus is put in its place, it’s the equivalent of taking 325 automobiles off the road in terms of emission reduction,” Harger says. He states that the conversion will also cause a 20 percent reduction in greenhouse gases.