At Schlitterbahn Waterpark on Galveston Island outside Houston, parkgoers love the 81-foot-tall Massiv Monster Blaster, which twists, turns, and drops for more than 900 feet. Not only is the slide fun—the attraction from WhiteWater also leverages energy-efficient technology that reduces the park’s carbon footprint and lowers utility bills.
Traditionally, the jets that power guests uphill on rides like the Massiv Monster Blaster run continuously and pump water nonstop. In an attempt to reduce the jets’ impact, WhiteWater introduced an energy-saving proprietary algorithm and leveraged readily available variable frequency drives (VFDs) to dynamically adjust pump speeds while the ride is in operation. This Smart Blast reduces power consumption by more than 50%.
“The new system saves significant power by only ramping up motor speed when it’s needed to drive riders uphill,” says WhiteWater Product Systems Manager Kelly Williams. “It also reduces the wear and tear on the mechanical equipment and is more energy efficient because the motor is not constantly running at a set maximum speed.”
WhiteWater’s Smart Blast is a proprietary system for specific rides. The innovation won an IAAPA Brass Ring Award for Best New Product Technology Applied to Amusements in 2016. But the underlying technology—VFDs and their sister product, variable speed pumps (VSPs)—are off-the-shelf systems that any attraction can use to reduce energy and water consumption. They can be installed on new purchases, retrofitted for older slides, and installed in wave pools.
“Variable speed pumps and variable frequency drives offer a transformative approach to energy efficiency and sustainability,” emphasizes ProSlide Director of Product Development Dan Thomas. “Investing in VSPs or VFDs saves costs and demonstrates a commitment to envi-ronmental stewardship and responsible resource management.”
Saving Money Is Green
Most waterslide systems pump water at a fixed speed. “You can only throttle the outlet,” says Williams. Some parks install butterfly valves to restrict water flow, but Williams likens this to “stepping on the gas pedal and the brake at the same time.”
VFDs and VSPs, in contrast, rely on magnets that are fixed to a rotor to generate a constant magnetic field. They adjust motor speed to match demand and enable precise control over equipment operation.
“You get the benefits of an AC (alternating current) motor in terms of power density and reliability, plus the benefits of a DC (direct current) motor by being able to change the speed,” Williams explains. “This results in massive power savings over the useable life of the attraction.”
Variable speed systems offer several additional benefits as well. They are quieter and help manage peak energy demand by reducing sudden spikes in power consumption. Parts and systems also last longer because there is less pressure on seals, lower motor torque, and less current. The pumps themselves wear out less quickly because they push against less resistance. Additionally, there is less heat and fewer greenhouse gases.
“Operating at lower speeds reduces stress on pump components, extending their lifespan and reducing maintenance needs,” explains Thomas.
“VSPs can also help regulate water flow more efficiently, reducing wastage and promoting sustain¬able water use.”
“VFDs are retrofittable on nearly every product, from every supplier, with an immediate power reduction,” says Williams. “By looking at ways to implement new technology on older slides, parks can find opportunities to reduce electricity usage through eliminating throttle valves. Going one step further, parks can reduce their consumption of water through spinning down a pump to minimum flow when the attraction is idle and waiting for riders.”
Water Hammers
One potential drawback of installing VFDs is that pressure surges can occur when a single pump is used to supply water to multiple nozzles, injectors, or toys. If any one of the water outlets is abruptly turned off or slowed down significantly, air enters the system. When turned back on again, a pressure shock wave, or “water hammer,” can occur when water reaches the outlet again and air leaves the system. This can lead to fractured pipes and damaged seals.
“VFDs are still useful in shared applications,” explains Williams. “But this limits their value because the water must keep flowing through every outlet. This is why we tend to recommend one pump per nozzle on higher-output applications.”
Capital Expenditure
Like many green investments—from fuel-efficient filters to refractive roof coatings—the biggest drawback to variable speed systems is often the initial cost, which can be significantly higher than traditional fixed speed pumps.
Over time, though, attractions that invest in green technology reap savings. In the case of variable speed systems, quantifying these savings depends on several factors, including the size of the pumps, operational hours, tower height, and cost per kilowatt-hour where the water attraction is located.
The case for installing variable speed systems in wave and surf pools may be even stronger. In these attractions pumps channel compressed air into a wave chamber to push the water down and create wave patterns. “You don’t need the pump to be running flat out,” says Williams, though this is the norm in pools that do not have variable speed systems. “With a VFD and a control system, you can carve it way back. It’s an immediate power savings. You will notice a significant reduction in your first power bill.”
“I’ve lost count of how many times clients have told me, ‘I can’t believe we didn’t do this sooner!’” says now-retired WhiteWater mechatronics engineer Keith Campden. “There’s a very compelling case to retrofit wave pools with VFDs.”
Despite these savings, purchasing teams may be reluctant to increase capital expenditure. The same is not true for operations teams. They are often responsible for recurring costs and, thus, more likely to take a different view. For this reason, Williams advises that both operations and purchasing teams be in the same room when making major buying decisions.
