One of the most popular attractions at SeaWorld Cleveland in Ohio is Dolphin Cove. SeaWorld animal care staffers teach their guests about dolphin anatomy and behavior, and show them how to give the signals used to put the graceful aquatic creatures through their performances.

Besides instructing its patrons about dolphin physiognomy and eating habits, SeaWorld could teach them about energy savings. It replaced the throttling valves of Dolphin Cove filtration pumps with adjustable speed drives, or ASDs.

Adjustable speed drives save energy at SeaWorld Cleveland's Dolphin Cove where future oceanographers feed the attraction's playful inhabitants.

Dolphin Cove's filtration pumps keep the attraction's 375,000 gallons of water free of contamination. The throttling valves were used to vary the output of the pumps' electrical motors, which were designed to run at constant speeds. Throttling motor output, although a typical configuration for many pumps and machines, wastes energy, because output varies but motors run consistently at peak power. Adjustable speed drives can change the voltage and frequency of the electricity sent to a motor, and thus adjust the motor's rotational speed to meet the desired pump output level. This improves overall pump efficiency.

"We first approached the Edison Electric Institute in the winter of 1997 to see if retrofitting the Dolphin Cove pumps with ASDs would be economically feasible," said Brian Oblisk, a wastewater treatment engineer and manager of water quality at SeaWorld Cleveland. Edison Electric Institute in Washington is an association of shareholder-owned electric companies that foster energy-efficient technologies.

The institute brought SeaWorld Cleveland together with FirstEnergy, the park's electricity provider, based in Akron, Ohio. For its part, FirstEnergy sought to provide more competitive services to customers such as SeaWorld in the face of the looming deregulation of Ohio utilities.

In September 1997, FirstEnergy engineers installed a three-phase power meter to a single Dolphin Cove pump to establish a baseline of its electrical consumption. The pump was a Sie-mens 30-hp, continuous duty, 1.5 service factor motor, with a nominal efficiency of 91.7 percent. The Ohio utility then used the ASDMaster software from the Electric Power Research Institute of Palo Alto, Calif., to analyze four Dolphin Cove pumps.

EPRI developed ASDMaster to analyze electrical motors' energy use, the benefits of equipping them with adjustable speed drives, the economics of ASD use, the ASD equipment itself, and to locate equipment vendors. "The ASDMaster includes over 100 interactive instruction pages that explain the basics of ASD application from a total system perspective," according to Roger Lawrence at EPRI's adjustable speed drive demonstration office.

"Using basic data about the system, and the way in which it was operated, ASDMaster told us what energy savings we could expect by retrofitting the pump systems with ASDs," explained Doug Hohlbaugh, the FirstEnergy representative who oversaw the project. Hohlbaugh and his colleagues installed a test ASD on the pump they studied to confirm their calculations.

ABB Industrial Systems of New Berlin, Wis., won the bid to supply a test ASD. A key consideration was that it not be a high-frequency unit, which could disturb the dolphins. Zesco Inc., ABB Industrial Systems' Cleveland- area representative, recommended and commissioned the ACS 500 series pulse width modulated drives for Dolphin Cove.

Like all PWM drives, the ACS 500s rely on computer software to control the frequency and voltage delivered to motors.

Metering performed by FirstEnergy after the ACS 500 was installed confirmed that adjustable speed drives would reduce pump electrical demand. Zesco then equipped all four Dolphin Cove filtration pumps in April 1998. "Since ASD installation, each pump's electrical demand has dropped from 21.7 kilowatts per hour to 17.8," Oblisk said. "This represents an $1,800 annual savings per pump. Because total installation costs are more than $5,000 per pump, the system will pay for itself in 3.5 years."

"Retrofitting the Dolphin Cove exhibit showed not only that ASDs work, but that our client can realize further savings by using this application in exhibits throughout the park," added Hohlbaugh. Indeed, based on the success of the Dolphin Cove project, SeaWorld Cleveland commissioned Zesco to equip the 20-hp Siemens electrical motors on the filtration pumps at its Whale and Dolphin Life Support exhibit, home of Shamu the Killer Whale, and Shark Encounter exhibit with adjustable speed drives during November 1998.