Jul 1, 2008 12:00 PM
With Energy costs projected to rise as much as 12% this year, and carbon footprint (total amount of greenhouse gases produced to directly and indirectly support human activities) an issue of increasing importance, cold storage facilities are taking a hard look at their energy consumption. Facilities can save tens of thousands of dollars in yearly electric costs, and cut harmful emissions by thousands of tons by implementing a handful of simple, cost-effective efficiency measures to reduce electrical consumption and have a payback period of three years or less.
There are three main areas of “low-hanging fruit” for a cold warehouse facility seeking to lower electric costs: refrigeration, electrical motors, and lighting, said David Simon, chief executive officer of Evergreen Energy Solutions, a Nevada-based an energy consulting firm specializing in reducing electricity use and cost (www.evergreensolves.com). Typically, refrigeration represents the largest component of the electric bill, generally accounting for 50% to 80% of the total cost.
“The efficiency of refrigeration systems can be improved three ways,” he said. “Put into operation controls to optimize the operation of refrigeration components, add oil lubricants to refrigerant, and treat fans and compressors to improve operating efficiency.”
Various controls can be used to improve the efficiency of refrigeration components. Such controls include:
Fan speed control — uses pressure or temperature signals to control fan speed, reducing electrical consumption when operating at lower speeds.
Lube oil control — monitors and controls compressor lube-oil circuits to ensure proper lubrication and efficient operation.
Defrost control — improves the efficiency of the defrost cycle by defrosting on demand rather than on a simple timer.
“Implementing a set of refrigeration controls can lower a refrigeration system's electricity consumption by 10% or more,” said Simon. “With payback periods as short as one year in some cases, refrigeration controls are a great place to start lowering electric bills immediately.”
Another way to improve a refrigeration system's efficiency is to add oil lubricants to the refrigerant. Oil lubricants serve to reduce friction in the compressor's moving parts, improving mechanical efficiency and lowering power consumption. Such additives may also provide other benefits, such as reducing wear on bearings and improving seal life.
A refrigeration system's electrical consumption also can be lowered by improving the efficiency of rotating motors found in equipment such as refrigeration units, chillers, fans, boilers, and air handlers.
Rotating electrical motors often account for 20% to 30% of a cold storage facility's monthly electric bills, Simon said.
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