Whereas Part I of this article ("Improving Energy Efficiency in Pharmaceutical Manufacturing Operations — Part I: Motors, Drives and Compressed Air Systems", Pharmaceutical Manufacturing, Feb. 2006) focused on motors, drives and compressed air systems, Part II will review, briefly, potential improvements in heating, ventilation and air conditioning (HVAC) systems, overall building management and boilers. Research in this article was first published last September, in an extensive report developed by the Energy Analysis Department at Lawrence Berkeley National Laboratories for the Environmental Protection Agency’s Energy Star Pharmaceutical Focus. The 90-page guide, “Energy Efficiency Improvement and Cost Saving Opportunities for the Pharmaceutical Industry,” is available in pdf format at www.energystar.gov.
The U.S. pharmaceutical industry spent nearly $900 million on energy in 2002. As energy costs increase, more companies are looking into energy efficiency measures (to view this table — a one-page PDF — click the Download Now button at the end of this article). Considered individually, each measure may offer small savings, but combined they add up to significant savings and short payback periods.
First, let’s consider HVAC systems, which consist of dampers, supply and exhaust fans, filters, humidifiers, dehumidifiers, heating and cooling coils, ducts, and various sensors . HVAC systems in manufacturing portions of facilities are closely supervised by the FDA and must meet other global regulatory standards, so energy efficiency measures that affect the work environment must conform to current Good Manufacturing Practices (cGMP). Although cGMP allows for new techniques, the reasons for using them must be explained — the additional time required, and the risks associated with a delay in approval of building plans, may have led some drug companies to stick with less energy-efficient designs.
Nevertheless, investing in newer technology frequently pays off. At its plant in Rzeszow, Poland, for example, Novartis installed microprocessor controls on its HVAC system that could be programmed to better balance plant heating based on outside temperatures, and reduce heating loads on the weekends. The company expects this new system to reduce overall heat energy consumption by 10% .
There are many energy efficiency measures that can be applied to HVAC systems; some significant opportunities are discussed below.
Non-production hours set-back temperatures. Setting back building temperatures (that is, turning temperatures down in winter or up in summer) during periods of non-use, such as weekends or non-production times, can lead to significant savings in HVAC energy consumption. Similarly, reducing ventilation in cleanrooms and laboratories during periods of non-use can also lead to energy savings.
At Merck’s Rahway, N.J. laboratory facilities, HVAC systems are designed with once-through air exchange based on safety considerations. To improve the energy efficiency of these systems, Merck utilized control technologies to lower selected room temperatures from 72°F to 64°F during nights and weekends. An interlock with room lighting overrides the set-back. This control strategy was implemented for rooms where lower temperatures would not impact scientific equipment, and covered 150 individual laboratory spaces encompassing over 350,000 square feet of floor space. The energy savings from this project totaled nearly 30,000 MBtu per year. The energy-related carbon dioxide (CO2) emissions avoided through this project amounted to over 1,700 tons per year .
Adjustable speed drives (ASDs). Adjustable speed drives can be installed on variable-volume air handlers, as well as recirculation fans, to match the flow and pressure requirements of air-handling systems precisely. Energy consumed by fans can be lowered considerably since they are not constantly running at full speed. Adjustable speed drives can also be used on chiller pumps and water systems pumps to minimize power consumption based on system demand. Genentech installed ASDs on variable air volume air handlers in its Vacaville, Calif. facility, leading to significant reductions in energy consumption and expected annual savings of around $23,000 per year .
Heat recovery systems. Heat recovery systems reduce the energy required to heat or cool facility intake air by harnessing the thermal energy of the facility’s exhaust air. Common heat recovery systems include heat recovery wheels, heat pipes, and run-around loops. For areas requiring 100% make-up air, studies have shown that heat recovery systems can reduce a facility’s heating/cooling cost by about 3% for each degree (Fahrenheit) that the intake air is raised/lowered.
In 2004, Merck installed a glycol run-around loop system to recover heat from HVAC exhaust air at a 37,000-square-foot laboratory building in Rahway. After installation, the building could pre-heat and pre-cool up to 120,000 cubic feet per minute (cfm) of outside air with recovered energy. The savings associated with this measure amounted to roughly 265 MBtu per year, which led to avoided CO2 emissions of over 30 tons per year .
Improving HVAC chiller efficiency. The efficiency of chillers can be improved by lowering the temperature of the condenser water, thereby increasing the chilled water temperature differential. This can reduce pumping energy requirements. Another possible efficiency measure is installing separate high-temperature chillers for process cooling .
Sizing chillers to better balance chiller load with demand is also an important energy efficiency strategy. At Genentech’s facility in Vacaville, two 1,400-ton chillers and one 600-ton chiller were chosen instead of three equally-sized chillers. This selection was made in an effort to operate the chillers at as close to full load as possible, where they are most efficient. The two larger chillers are run at full load and the smaller chiller is run to supply additional cooling only on an as-needed basis, reducing energy needs. The cost savings associated with this chiller selection strategy were estimated to be $113,250 per year .