Lean, Mean, Energy Machines

January 1, 2002
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Last year's California energy calamity was a wakeup call to improve efficiency in food and beverage plants

California's energy crisis bears an uncomfortable resemblance to Gary Condit and other transitory news stories of 2001: after a few months in the national limelight, both were vague and distant memories by the time winter rolled around.

The story of the married congressman and his assignation with a missing intern was of dubious merit from the start, designed to titillate rather than inform. California's rolling blackouts and skyrocketing energy prices, on the other hand, exposed half-baked energy policies and the risks they pose to major energy users, notably food manufacturers. The media lost interest in the Condit melodrama after Sept. 11. Similar disinterest seems to have overcome the energy crisis, as California's shortages have abated and energy prices nationwide have tumbled.

Energy efficiency is a tough sell, especially when prices are low and supplies are plentiful, but last year's California crunch succeeded in putting machine and plant efficiency on manufacturing's radar. It also yielded some strategies that other food processors should consider to reduce their exposure to a similar situation at their plants.

"California's electric rates are basically frozen at about 40 percent higher for the foreseeable future," reports Ed Yates, executive vice president of Sacramento-based California League of Food Processors. "Gas prices have returned to nominal historic levels.

"The short term looks stable, but I don't know what awaits in 2003 and beyond. Processors are hanging in there and adjusting their operations and procedures to cope."

"It's a very challenging time, and there's a lot of uncertainty," adds Glen Lewis, western region procurement manager for Del Monte Corp. "Energy efficiency alone cannot overcome it."

The tradeoff for reliable energy supplies has been higher prices, with electric tariffs anywhere from 10 to 80 percent higher at year end in California, depending on time-of-day. "All you can do is look at optimizing the demand side," Lewis reflects. "Not only motors and other equipment, but all aspects of operations management."

Electric tariffs hover in the 18 to 19 cents per kilowatt hour in the noon to 6 p.m. period, Yates says, about twice the off-peak rate. Frozen food companies have taken steps to minimize operations during those hours, and processors of seasonal crops have tried to shift as much activity to off-peak hours as possible. A 20 percent dip in last summer's tomato crop -- California accounts for 40 percent of worldwide tomato processing, according to Yates -- helped ease demand, and the economic slump is buffering energy users from strains to the supply-demand balance.

Much of Lewis's focus has been scheduling and other tactics that shift consumption patterns away from peak tariff periods and toward day parts when energy prices are more affordable. An operations and energy management specialist, he is responsible for Del Monte's fruit and vegetable production plants, working from his Modesto, Calif., office. "You're somewhat hamstrung and helpless on the tariffs, so the best you can do is focus on demand-side process efficiencies and technologies," Lewis says.

He advocates a comprehensive review of each plant and its operations. Can energy-intensive processes be shifted to non-peak tariff periods? Is the sequencing of tasks being done in the most cost efficient way? "Motors and lights are good starting points, but to limit your evaluation to that is very myopic," he says. "You have to do an operations assessment, not just an energy assessment."

Looking at energy in isolation caused some processors to reexamine cogeneration, particularly with availability in question. "In retrospect, a lot of money was wasted on self-generation projects," notes Yates. "The price of electricity isn't quite high enough to justify co-generation, and most of the state's processors operate seasonally."

By recirculating half of the exhaust from a fluid bed dryer, engineer James Schak was able to slash overall energy demand by 20 percent for this hybrid cyclone/bag collector system.

Right message, wrong time

The tumult of a year ago is still fresh in California processors's minds, so they are making changes. In Wyoming, electricity prices reached 30 cents per kW before abating, and natural gas prices walloped users nationwide last winter. But the return of cheap energy prices has pushed efficiency into the background for many.

Promoting the payback from super-efficient motors probably looked like a good idea when suppliers formulated their Motor Decisions Matter campaign, which commenced in June. Backed by premium-motor manufacturers such as Emerson, GE, Siemens and Reliance/Rockwell, the campaign was predicated on a U.S. Department of Energy finding that only one in 10 buyers were considering energy operating costs when sizing, repairing or replacing electric motors. Given that electric motors account for 60 percent of U.S. industry's energy consumption, the consortium saw an opportunity to help manufacturers economize by teaching them how to calculate the economic payback on premium-efficiency motors.

Unfortunately, electrical and other fuel costs began to wane about the same time. By the fall, spring's operating assumptions no longer were valid. Just as consumers stopped entertaining thoughts of trading in their SUVs for a Geo, manufacturers started looking elsewhere for capital investments with a quick return.

The Energy Policy Act of 1992 raised the bar on electric motor performance. The mechanical energy output of a standard efficiency motor is within 4 percent of the performance of a premium-efficiency motor. But even a modest improvement can be enough to justify buying a premium motor, though it can mean waiting three years for a return on investment.

"We believe that premium efficient AC motors account for something under 30 percent -- probably 25 percent -- of the installed motor base," estimates Rick Payton, director of motor marketing for Rockwell Automation's power systems business unit in Greenville, S.C. "Customers used to want a payback in three years. Now they want it in one year.

"When the lights went out in California, it was a huge wakeup call for us to get back out in the market and tell the motor-efficiency story again," Payton continues. The era of cheap energy that began in the early '80s resulted in the story falling on deaf ears, and a similar fate may torpedo this retelling.

"Electricity is still a hell of a bargain," agrees Jerry Pollack, drive systems application engineer in Rockwell Automation's Cleveland office. "The educational work we're doing today on pumps and fans is the same that we were doing in the late '70s, and it's like we're saying it for the first time."

Condition monitoring runs smack into the same wall. Vibration analysis and other tools are considered aids to machine maintenance, and intuitively one would assume that a precision alighed machine draws less power than a misaligned unit. But debate surrounds the issue of energy consumption, with some experts insisting that well-aligned machines only realize Reactive Power savings, which have no bearing on the Real Power consumption that is the basis for electricity charges.

Miami-based Ludeca Inc. undertook a comparative study at GM Powertrain in Toledo, Ohio, to determine the impact of shaft energy losses on Real Power consumption. Ludeca technicians performed 15-minute spin tests on coupled machine sets, one of which was misaligned to the degree judged typical of new installations before precision alignment is performed. Machines were operated unloaded and with a 25 percent load.

The unloaded, precision-aligned machine used 9.1 percent less energy than the misaligned unit, the technicians determined. With a 25 percent load, the savings dropped to 2.3 percent. "We should expect somewhat smaller energy savings for an induction motor loaded between 75 and 100 percent, perhaps somewhere in the neighborhood of 1 percent," researchers concluded. "Nevertheless, a most remarkable finding is there apparently exist measurable differences in Real Power consumption between aligned and misaligned machines."

In fact, 60 percent loads are fairly typical for industrial motors, Rockwell's Pollack suggests. Grossly oversized fans and blowers are more the rule than the exception, he says, because systems typically are designed for worst-case normal loading and a prediction of future needs.

Food plants are loaded with inefficient compressed-air systems and conveyors powered by fractional HP motors tied to gearboxes that magnify their inefficiencies, Pollack says. Add to that stubbornly low penetration for adjustable speed drives, and the potential savings are enormous. "We don't seem to be making any progress," he says ruefully. "On centrifugal loads, retrofitting variable speed drives is relatively straightforward. If you slow the motor 10 percent, the load drops like a rock."

The most visible energy-intensive units in a food plant usually are the compressors that drive the refrigeration system. Boosting motor efficiency is only part of an effective strategy. Shedding load to avoid peak demand penalties can yield a much faster payback. That was the experience at ConAgra's beef and pork processing plant in Mason City, Ia.

A dozen compressors consumed half the plants electricity to cool the 200,000-sq.-ft. facility. Equipment startups in the morning produced demand spikes that resulted in penalties of up to 50 percent of the base rate. By installing an Allen-Bradley power monitoring module, managers were able to level demand. They also generated energy-consumption data that was essential to claim an $80,000 rebate from the local electrical utility.

Unfortunately, rebates from utilities often go unclaimed, Payton points out, and industry is looking for alternative ways to distribute incentives. One alternative is to channel the rebates through distributors to motivate them to sell efficiency-enhancing devices. Another is Efficiency Vermont, the nation's first statewide energy-efficiency utility. Surcharges previously collected by the utilities have been pooled under Efficiency Vermont, which actively promotes the funds' availability to individuals and business. In the program's first 18 months, rebates totaling $188,000 were distributed to food and beverage companies, program administrators say.

Among the recipients is Cabot Creamery, a farmer-owned cheese cooperative that's part of Agri-Mark. When the company's Middlebury, Vt., plant was in the market for a new 250 HP motor to power the ammonia system's screw compressor. Efficiency Vermont dangled a rebate that would make up for half the $12,000 additional cost of a premium-efficiency motor. "Farmers are stewards of the land," points out project engineer David Brault, "and they take conservation very seriously." But since the premium motor would also cost $18,000 less a year to operate, "it was a no-brainer" to take the rebate and buy the high-efficiency motor, he adds.

Roadblocks to efficiency

Equipment manufacturers are under the gun to deliver their systems at the lowest possible cost, so premium efficiency components are unlikely. "The OEM is looking for a motor he can source from a number of suppliers quickly and get it at a relatively low price," Rockwell's Pollack notes. Unless the buyer insists on efficient components, they won't be incorporated, but that scenario seldom plays out.

Misconceptions and a lack of understanding of the engineering dynamics behind complex systems can prevent food clients from specifying efficient equipment, observes James A. Schak, process engineering manager with the Witte Co., Washington, N.J. For example, recycling the exhaust from fluid bed dryers has been recognized in engineering circles as an effective drying efficiency for 20 years, yet "only about 10 percent of our dryers have had the technology," he says. The ratio is starting to increase, but poor understanding of drying dynamics and failure to accurately estimate savings still make it a tough sell.

Schak recently designed a two-stage drying system that combines an economical cyclone dust collector with a more efficient bag collector (upper right in diagram) to dry seeds. Half of the exhaust air is recirculated back into the dryer without clogging the air heater. The fresh air used in the second-phase of the dryer achieves the lowest final moisture possible. Assuming the system runs 120 hours a week, recirculating exhaust will save $24,300 year if gas costs $5 per million Btus.

"When you're looking at $9 per million Btus, it's ridiculous not to recirculate," he says.

But many manufacturers mistakenly believe that recirculating exhaust will increase moisture levels in the exhaust air and cause condensation. They fail to consider that the dew point of the recirculated air is so far below the exhaust's temperature that condensation in the exhaust dust collector isn't an issue. "Drying has been viewed as an art," Schak reflects, "but you can consult a psychrometric chart and see that you never get close to the dew point with 99 percent of these systems."

Of course, manufacturers are more interested in reducing initial costs than adding to them when purchasing equipment in the six- and seven-figure range. But as California's experience with deregulation makes clear, removing portfolio management responsibility from regulated utilities and assigning it to the power marketplace either produces supply disruptions, price increases or both.

The California experience also underscores the role of greater efficiencies. Since 1998, incentive programs are credited with a 1,600 megaWatt reduction in electric consumption that otherwise would not have occurred in the Golden State. Absent those efficiencies, current prices might be even more onerous.

Mechanical efficiency is not a tough sell with engineers. Financial managers are another story, and price elasticity tends to undermine the cost assumptions in payback models. But progress is being made, and a better understanding of the true costs of manufacturing should accelerate it.

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