Industrial strength energy efficiency

When it comes to energy efficiency, the focus is usually on the home but far greater savings await in commercial and industrial environments.

What do you think of when you hear the phrase, “energy efficiency?”  Compact fluorescent (CFL) lighting?  Maybe Energy Star appliances or adding insulation to your attic.

What all of these things have in common is that they are all residential solutions, but despite their greater numbers residential customers use far less electricity than do commercial and industrial customers.  Certain industries (e.g. cement, steel, aluminum) use enormous amounts of power, but the efficiency conversation rarely touches on these users.

That’s unfortunate because industry is where the big potential savings are.  Consider that while all lighting (residential, commercial, industrial combined) accounts for around 5.5 percent of total electricity consumption, electric motors in industrial applications alone use nearly five times as much, fully 25 percent of all electricity consumption.

Motor control devices known as drives allow motor speed to ramp up and down with demand instead of being run at a constant speed and then braked to modulate the output, a very inefficient process.  Drives essentially act like dimmer switches, but here’s where physics really closes the deal.

The relationship between a motor’s speed and the amount of power it uses is not one-to-one (i.e. linear).  In fact, power varies with the cube of the speed. Doubling the speed means increasing the power draw 8X.  It works in reverse, too: reducing the speed by half means reducing the power by a factor of 8.

To understand what this means in real-world terms, consider the following example using data from the US Energy Information Administration.

The average US home uses around 1,600 kWh per year for lighting.  In a best-case scenario, switching the whole house from incandescent bulbs to CFLs would yield about 1,200 kWh per year in savings.  On the other hand, a moderately sized supermarket of 50,000 square feet (4,645 m2) will use about 143,000 kWh per year for cooling alone.  To use a very conservative estimate, applying variable speed drives to the HVAC system might reduce energy consumption for cooling by 20 percent, which equates to 28,600 kWh in savings.

In other words, it would take 24 “average” homes to convert entirely to CFLs in order to produce the same energy savings as one drive system in a relatively small application.

In fact, drives have been shown to reduce energy consumption in motors by as much as 70 percent or more in some situations, and when you consider that large industrial facilities measure their consumption in MEGAwatt hours (i.e. 1,000 kWh), the potential for substantial efficiency gains becomes obvious.

So, would you rather convince hundreds or even thousands of families to change tens of thousands of light bulbs, or would you rather convince one business to invest in an efficiency technology that typically pays for itself in less than two years?


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Image credit: Daniel Rothamel on Flickr

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About the author

Bob Fesmire

Bob Fesmire is a Content Manager at ABB, based in Cary, North Carolina. He has written more than 150 articles and white papers on a variety of topics including energy efficiency, industrial automation and big data. In addition to his work at ABB, Bob is also the co-author of Energy Explained, a non-technical introduction to all aspects of the energy industry.
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