More Copper Equals Big Energy Savings
Generous use of copper pays off many times over in savings of energy and money. This was the message reiterated at a meeting of copper industry executives earlier this year by three experts: Austin H. Bonnett, vice president of engineering, U.S. Electric Motors Div., Emerson Electric Co., St. Louis; David S. Dodge, director of engineering, Magnetek/Power Magnetics Inc., Gardena, California; and Thomas E. Shepherd, retired associate director of physical plant, Massachusetts Institute of Technology, Cambridge.
More copper cuts I 2R losses. Respect for this immutable law of physics is common in the design and specification of electric motors. The most recent figures are for 1991 when an impressive 42% of the largest motors built in the U.S.A. were of high-efficiency design with lowest losses, according to Austin Bonnett. However, adherence to energy-efficient design declines as motors get smaller. Only 5% of motors under 5 HP are of high-efficiency design.
High-efficiency motors not only save a lot of energy, Bonnett added, but also operate cooler and last much longer than conventional motors of equal power. (The chart below details these savings.)
|Energy Efficient Motor
3HP, 1800 RPM,TEFC
230/460 V, 1.15 svc factor
insul: Class F, NEMA: B
Full Load Eff: 89.5%
Standard Efficiency Motor
|Annual Savings||@ $0.06 per kWh||@ $0.08 per kWh|
|Simple Payback||Annual Savings||Simple Payback||Motor Load Situation|
|Example savings gained by specifying premium-efficiency motors. When used for more than one shift, premium motors can pay for their added cost in under a year.
Source: General Electric Motors
|2,000 hours/year (1 shift)||$20.00||2.1 years||$26.00||1.6 years|
|4,000 hrs/year (2 shifts)||$40.00||1.0 years||$52.00||0.8 years|
|8,760 hrs/yr (Full Time)||$86.00||0.5 years||$114.00||0.4 years|
High-efficiency Transformers: Untapped Opportunity
One of the nation's greatest opportunities for energy savings is in voltage stepdown transformers, said Dave Dodge of Magnetek. He explained that doubling the amount of copper in one of these transformers raises its cost by 50%. However, energy savings over the usual 15- to 20-year life of stepdown transformers recoups this added cost very quickly and many times over, especially in high energy cost areas.
Unfortunately, according to Dodge, only engineers specifying such transformers for some power utilities and for naval vessels are buying high-efficiency models. Other engineers and buyers, specifying approximately one million stepdown transformers annually for use in buildings and outdoors, are choosing conventional versions because they cost less to buy.
Unfortunately, this cuts off the transformer user from the cost savings they would enjoy if a high-efficiency unit had been specified.
As in motors, the high-efficiency transformers also operate cooler and last longer. The high-efficiency versions, Dodge said, are also much quieter.
More Copper Helps Save $100 Million
Tom Shepherd is another advocate of generous specification of copper. He insisted on next-size-up cabling throughout the 109-building MIT campus. This not only cut energy losses, but ensured delivery of proper voltages where needed for voltage-sensitive equipment. Another benefit was postponement of costly recabling, because the heavier cables could deliver more power safely as demand inevitably rose.
Next-size-up cabling, using larger diameter wires than called for by the National Electrical Code, was one of many saving measures Shepherd instituted from 1972 until he retired earlier this year. The result was total savings of $100 million. MIT invested only $11 million to gain these impressive savings, and half this investment was recouped in rebates from the local utility.
Arguably one of the most effective facilities managers in American education, Shepherd noted that America's higher education institutions must spend some $60 billion in the coming years to repair or replace facilities erected in the 1960s and earlier. This offers a lot of opportunities for cost savings through increased use of energy-saving copper.
Government Encourages Higher Efficiency
Greater use of high-efficiency motors, transformers and cabling will be encouraged by a new federal program. "Our purpose is to encourage those who put up large buildings to specify higher-efficiency electrical products wherever possible," said John Hoffman, director of the Global Change Program at the Environmental Protection Agency.
The Administration is also promoting use of high-efficiency motors and variable-speed drives in factories, Hoffman added.
Emerson Electric: 314/595-8400
GE Motors: 800/626-2004
Also in this Issue:
- Copper Alloy Essential to Bloodless Surgery
- Copper Highlights Resource Conservation House
- More Copper Equals Big Energy Savings
- Copper and Brass Strengthen Stained Glass