CHP Energy Plant Saves Millions at Army Base
When an ice storm crippled central Kentucky in January 2009, knocking out power to the military base at Fort Knox for five days, U.S. Army officials vowed it would never happen again.
But even before the storm, efforts were underway to develop a separate source of on-site power stemming from the 2007 Energy Independence and Security Act, which required a higher level of energy security at military installations. This year, Fort Knox completed a $60 million energy project that provides the sprawling base with 44 MW of peak-load power. Four of six gas-fired Cat® G3520C generator sets supply power to the base 24/7 through a combined heat and power (CHP) system. The installation also includes 10 Cat 3516 diesel gensets that are used primarily for backup power. The gas and diesel units are housed in six separate power stations that comprise the micro grid at the 109,000-acre base, which is located 35 minutes south of Louisville. The power stations all utilize Cat ISO Switchgear, which integrates monitoring and control of the Cat generator sets in a single-source package. Beyond providing energy security, the new power system is reducing the base’s energy costs by an estimated $8 million per year—with $4.5 million of the savings coming from the CHP system. The other $3.5 million is derived from peak shaving during periods of high demand, such as the summer, when highs can exceed 90 degrees for weeks at a time. Total project payback is expected in approximately seven and one-half years.
A world leader with the Energy Act of 1995, all government agencies were tasked to reduce energy consumption at a rate of 1.5 percent, year over year.
“So that’s goal number one, and Fort Knox is achieving that, as one of the best, if not the best military base in the world in terms of overall energy reduction,” says Tom Abele, a vice president for project developer Harshaw Trane. Adding to the overall sustainability effort, Fort Knox expects to complete a project converting methane gas from shale gas reserves on undeveloped
land that is part of the base into enough electricity for the entire post, deputy garrison commander Emmett Holley said in a published report. Harshaw Trane was hired to provide energy security to the base, and the challenge was to do it in a way that paid for itself, Abele says. “We ran multiple scenarios and considered various solutions, including alternative fuels, biodiesel, waste-to-energy, coal and big turbines,” he says. “Nothing made as much sense as CHP.” On average, Fort Knox purchases about 22 MW from the local utility, Louisville Gas & Electric, and the rest will come from its own power plant. “In terms of kilowatt hours, only about 25 percent of the power for the base will be produced here,” Abele says. “The rest of the power will still be purchased, but it will be without those high demand penalties, and that’s where you start to achieve load unity or power unity.” CHP systems are efficient, as they capture heat that is generated when producing power. Buildings use the captured heat in their facilities in various forms, such as steam heat, hot water, and in chillers to produce air conditioning. This can dramatically lower annual heating bills. At Fort Knox, Ireland Army Community Hospital is a prime customer for CHP, as waste heat from the generators is used to heat the building, sterilize equipment, and cook the food for patients and staff. The gas generators also provide about 80 percent of the steam and chilled water that the hospital requires. Captured heat from the gensets is converted into chilled water to serve Fort Knox’s data center, which requires constant cooling. “So our savings come from demand reduction, or kilowatt consumption avoidance,” Abele says. “In this case, we’re air conditioning and heating the hospital, which is essentially a 400-bed facility. We are providing all the air conditioning for an extremely large data center at the Human Resources Center, and we’re also providing heating and air conditioning for a shopping center, a PX and a furniture store. “So when you add up all of the energy avoidance from the thermal side of the combined heat power, and the avoided energy to provide the heating and air conditioning for those facilities—add that to the electricity savings of the CHP, and it totals about $4.5 million,” he says. An economic dispatch model developed by Fellon-McCord dictates when it makes the most sense for Fort Knox to purchase power, and when it makes sense to generate its own power. The model has been refined to the point where it indicates every 15 minutes how much power the base should purchase and/or produce on its own.
Partnering with Boyd CAT Cat dealer Boyd CAT Power Systems provided 16 of the 21 total generator sets for the project, as well as serving as a consulting partner when the system was engineered. To find the right mix of generators, consideration was given as to how each building on the campus is used, which helped determine where each genset should be placed, said Steve Killian, a sales engineer for Boyd CAT Power Systems. “Boyd CAT Power Systems’ involvement was critical to successful implementation, and they’ve been here since startup,” says Greg Lee, an operations engineer for Nolin RECC, the onsite owner-operator of the power plant. “This has been a lengthy process and certainly the biggest that we have ever taken on as an organization,” Lee says. “Along the way, no matter how well you’ve prepared, there have been certain things that just couldn’t be forecast. Fortunately for us, we’ve had the Boyd CAT technicians and engineers who can resolve any issues we encounter, or put us in touch with the right people at Caterpillar.” The selection of the Cat generator sets at Fort Knox was based on the fact that they were the right fit for the project, their reputation for durability, and also the close proximity to the resources of Boyd CAT in Louisville. “The efficiencies of these generators, as well as the sizes that we needed, really matched up with how we wanted to spread. hem out across our distribution system,” Lee says. “We never wanted to be in a situation where we had one or two or three really large, centralized generators. We wanted the redundancy of several smaller generators. That way we aren’t putting all of our eggs in one basket.” The switchgear was installed and programmed by Caterpillar ISO, based in Alpharetta, Ga. The Cat switchgear is essential for Nolin to coordinate the use of all the generators across the base. “They were able to help us find a way to interface each individual switchgear PLC with our economic dispatch PLC, which provides the automated control from one central location,” Lee says. Caterpillar and Boyd CAT Power Systems have been involved in several critical aspects of the project, which is expected to be fully complete in March 2015, Lee says.“Caterpillar and Boyd CAT has been involved almost from the beginning, and they’ve been able to help us achieve the results that we want.”