Cogeneration Plant Generates Success
The 270 employees of the USDA's Agricultural Research Service (ARS) research animal diseases at the NADC's 80-building, 450,000-sq-ft center located in Ames, IA. Opened in 1961, the center has about 250,000 sq ft of building devoted to housing animals, with offices taking up most of the remaining space.
Many of the animal research areas are biocontainment areas that require HEPA and other air filtration methods and all of the air ventilation is 100% outside, single-pass air. The air is conditioned at 10-15 changes/hr to meet animal care standards, and nearly all of the center's systems require redundancy.
Dennis L. Jones, facility engineer for the center, says about 90% of the facility's energy is used in conditioning outside air. The center's $1.2 million to $1.6 million annual energy bill had accounted for 7% of its total operating funds, including salaries and benefits, etc., according to Jones. In 1997 a decision was made to attempt to reduce the facility's energy expenditures, improve operational and maintenance efficiency, and improve indoor air quality (IAQ) and employee comfort with minimal expense.
Collaboration Delivers ConsistencyFor several years, NADC had been working with Johnson Controls utilizing the GSA Federal Supply Schedule to purchase and expand its Metasys(r) Building Automation System. The system monitors and controls the power plant, hvac systems, and pressurization of the laboratory area and animal housing facilities.
The Metasys system also integrates security through Cardkey(r) access control. Proximity card readers control access to the administration areas, research laboratories, and animal holding areas. An NADC-Johnson Controls team meets monthly to keep projects on track.
But as the facility's energy requirements increased and funds were not available for renovation and upgrades, NADC turned to Energy Savings Performance Contracting (ESPC) to finance major facility energy conservation and control improvements with no costs to taxpayers. Using the streamlined DOE Midwest Super ESPC contract, NADC selected Johnson Controls as the vendor. Continuing its collaborative effort with NADC staff, Johnson Controls audited the buildings and developed a plan to save energy and money while increasing employee productivity. They also coordinated the funding and guaranteed the results.
A USDA modernization plan also called for the demolition of several major buildings over the next decade. The plan required the power plant to remain open during construction of the new $440 million facility consolidation and renovation. Johnson Controls considered a variety of payback items. Short-term considerations included lighting and heat recovery systems in existing buildings, and longer payback items including chillers and a utility rate review.
Cogeneration Power SavingsPerhaps most noteworthy is the inclusion of a cogeneration power unit. This natural-gas-driven combustion turbine generates 1.2 MW of electricity, and then uses the heat from the combustion process to generate steam through a heat recovery boiler. "The cogeneration unit was the cash cow. It was appealing to us for several reasons, but mainly for the reliability of energy," says Jones.
NADC is now able to produce electricity for less than the current utility rate, and the steam is essentially a free byproduct used to run sterilizers and generate hot water. The installation of the cogeneration system allows NADC to purchase electricity and gas on interruptible rates, reducing the overall cost of utilities.
Installation of the natural-gas-driven turbine and a 1.8-MW diesel generator provides NADC with the capability to generate all their electrical needs on site, should availability of commercial power be restricted. The on-site generation brings flexibility to NADC. Decisions can be made on whether it is more economical to generate all or part of the electrical needs on site or to purchase commercial power, Jones adds.
The project reduced annual energy costs by at least 30%, exceeding the goals of Presidential Executive Order 13123, and Jones says it has saved or avoided an average of $550,000/yr in energy costs. Additionally, use of the new cogeneration system has reduced combustion emissions and the project improved IAQ and safety conditions for employees while reducing lighting maintenance.
"On average, it has roughly reduced our electric costs by a quarter, and for me, as a facility manager, it has given me generating capacity so now I can handle all loads at our facility," says Jones.ES