Switching Gears to Save Energy Costs

Jan. 1, 2011
High efficiency motors and gear reducers can make a dramatic impact on energy cost and consumption.

Efficient warehousing and distribution centers owe some of their efficiency to the electric motors that drive everything from conveyor belts to overhead doors. Today’s motors have become an essential part of facility operations, and play a key role in any plan to reduce energy and operating costs.

Industrial Energy Consumption

According to the U.S. Department of Energy (DOE), the industrial sector has been the country’s largest energy user, currently representing more than one-third of the country’s total energy consumption. One component factoring into this excessive energy use is electric motors, which account for an estimated 65 percent of industrial electrical use. Additionally, more than $30 billion is spent annually on electricity dedicated to electric driven systems, of which, nearly 70 percent goes to motor systems.[1]

With the continuing trend of increasing energy demand and rising energy costs, conserving energy is extremely important. That’s hard to do in warehouses and distribution centers where electric motors are almost always on. However, there is a way to reduce energy consumption and costs while increasing efficiency.

Gear Reducers

Gear reducers may be one of the most cost-saving components of a power transmission system. While it is true that switching to an energy efficient motor is a smart investment in most cases, it is only part of the overall energy savings equation. According to the DOE, greater attention to power transmission system management can reduce motor energy costs by up to 18 percent while also boosting productivity, reliability and profitability.

Substantial energy and operating cost savings are gained by combining premium efficient motors with highly efficient gearing, and the choice of gearing can have a significant impact on energy usage. Gear reducers are commonly used for speed reduction and torque multiplication; however, during this process the gearing consumes a certain percentage of power. Obviously, as power losses are reduced or minimized, system efficiency improves.

If appropriately sized for the application, gear reducers provide reliability and measurable efficiency. They are available in several materials, styles and configurations, and come in a variety of gearing types, including worm, helical, spur, bevel and planetary.

Worm gear reducers are the most common types of gearing in the industrial marketplace because of their low initial cost, long service life and ability to withstand high overloads. However, one of the drawbacks of worm gear reducers is their relatively low efficiency. Much friction is caused by the worm gear design and at high ratios this can cause the reducer to be only [approximately] 50 percent energy efficient.[2]

Replacing them with in-line helical reducers can result in energy savings from higher reducer efficiency and also provides the opportunity to reduce motor horsepower. Helical gearing technology delivers a wide range of ratios while maintaining 98 percent efficiency per stage of reduction; helical-bevel right-angle gearing technology delivers efficiencies of up to 95 percent. Conversely, a single stage worm gear reducer’s efficiency can be as low as 50 percent.[3]

Helical gearing owes its efficiency to how the torque is transmitted between gears through rolling motion. For a worm gear, torque is transmitted through sliding motion between the worm and the worm gear. This sliding motion causes considerable friction and heat, which leads to greater efficiency loss than other types of gearing.

The efficiency of helical gearing ensures that a high proportion of the energy being input into the speed reducer is multiplied and transmitted into torque rather than being wasted on mechanical losses inside the gearbox. Compact, high efficiency products are now available to directly interchange to most major brands of worm gear reducers. This provides a unique combination of both compactness and power transmission efficiencies and offers the maximum speed reduction in the smallest package.

Mandates, Rebates and Incentives

The Energy Independence and Security Act (EISA) went into effect December 19, 2010, and has far reaching implications for many industries. While the act has numerous goals and mandates – 300 pages worth – the EISA addresses raising the efficiency of industrial electric motors and expands the range of motors that are in question.

Although not affected by the EISA legislation, high efficiency gear reducers can certainly lessen energy consumption. Currently there is no legislation specifically for gear reducers.

However, a few of the industry’s forward-thinking manufacturers are proponents of Congress introducing laws targeting the efficiency of gear reducers.

Electric motors and their accessories may not be the highest-priorities of equipment buyers, but being aware of energy issues, both before and after purchase, can improve a facility’s “green profile”—in terms of both environmentalism and dollars. Incentives, tax credits and accelerated depreciation are helping companies upgrade to premium motors and gear reducers, which decrease energy costs and lower CO2 emissions.

Some states are both mandating efficiency and offering incentives for upgrading to energy efficient technology. For example, in California efficiency has been a key policy for 30 years, and it is widely credited with keeping per-capita power consumption flat. But it’s also an ongoing battle.

“We’ve been so incredibly inefficient as an economy and as a society, that there is more and more to do,” says Dan Adler, president of the California Clean Energy Fund, a nonprofit venture fund set up in the wake of the energy crisis nearly 10 years ago. “The low-hanging fruit grows back when it comes to energy efficiency; you have to keep picking it.”

California’s legislature and governor realize that maintaining the economic health of California’s business and industry is vitally important but not at the cost of precious resources and emitting carbon. To that end, in 2006, the Legislature passed and Governor Schwarzenegger signed AB 32, the Global Warming Solutions Act of 2006, which set the 2020 greenhouse gas emissions reduction goal into law. Assembly Bill 32 will compel California companies to document by 2012 the steps they are taking to reduce carbon footprints, with a target of 20 percent reductions by 2020.

Surprisingly, because of California’s massive and growing economy, the state is the 12th largest emitter of carbon in the world despite leading the nation in energy efficiency standards and its lead role in protecting its environment.[4]

Several states east, the Wisconsin Food Processing Plant and Food Warehouse Investment Credit is being applied to modernize or expand food processing plants or food warehouses. It is a refundable tax credit for businesses using technologies certified by the Wisconsin Department of Commerce.

Tax credits are earned by incurring eligible expenses for modernization or expansion of a food processing plant or food warehouse. This includes constructing, improving or acquiring buildings or facilities, or acquiring equipment for food processing or food warehousing.

The Business Case

It doesn’t matter whether a production, warehouse or distribution center is 10,000 square feet or one-million square feet, there is a strong business case for sustainable practices and operations. Sustainability cuts costs and contributes to operating efficiencies.

About 16 percent of commercial building space nationwide is warehouses,[5] which represents a significant opportunity for improved operations, lower operational costs and reduced environmental impact. Energy efficient motors that utilize gear reducers help facility managers value these changes not just from an environmental standpoint but from an economical one as well.

[1] http://www1.eere.energy.gov/industry/bestpractices/motor_challenge_national_strategy.html

[2] Werger, Jennifer. “Food Processing Machinery: Improving Energy Efficiency,” Applied Industrial Technologies, published 2009, FoodProcessing.com

[3] Fulton, Mike. “Maximizing Energy Savings by Replacing Motors and Reducers,” Plantservices.com

[4] http://gov.ca.gov/press-release/4111/

[5] http://smartenergy.arch.uiuc.edu/pdf/Warehouse%20Niche%20Market%20Report.pdf