Charlotte, N.C.-based Nucor Corp.—a steel recycling company—faced a range of inefficiencies when it purchased the Marion Steel Co. in Marion, Ohio. The previous operators relied on estimates to determine the amount of steel to be placed in the furnace. Inaccurate estimates were leading to unsatisfactory end products that had to be recycled again. Meanwhile, the plant was struggling to comply with state energy regulations.

To correct the problem, Nucor introduced a scale and weighing system using control products from National Instruments Corp. (NI) , of Austin, Texas. “The system gives us better control of the scrap metal, which means we’re not under-utilizing or over-utilizing the capacity of the furnace,” says Dave Brandt, electrical engineer at Nucor. “Using the National Instruments controller, we can efficiently measure the weight of what we’re putting in the furnace.”

The weight control allows operators to run a more efficient process. “When we have the right weight, we can eliminate reheating and other unacceptable processes,” says Brandt. “The controller helps save energy by optimizing the performance.”

Another energy problem that plagued the plant was the electric flickering that occurred when a large amount of energy was used to heat the furnace for recycling. The flickering was inconvenient for Marion residents and prompted monetary penalties for Nucor. To end the flickering, Nucor installed an online reactor in series with the furnace that measures the amount of energy drawn from the power grid. If the furnace approaches the prescribed limit, the system can quickly change methods to reduce the amount of power being drawn.

Nucor is part of an emerging trend of bringing control tools and technology to the management of energy. In the case of Nucor, the goal was to create a more efficient manufacturing process. But many plants are using automation systems to reduce energy for costs savings and to reduce their carbon footprint.

Plant operators are more concerned about energy consumption these days. Just a few years ago, energy consumption was not a large concern at plants. Energy was cheap and few cared how much you burned. But two trends have changed the consciousness of plant managers. The cost of energy has soared, and the need to reduce carbon emissions has become a powerful social motivator.

Track & reduce

So plants have turned their attention to reducing energy consumption, both to save money during difficult economic times and to drive down carbon emissions. Since you can't change what you can’t measure, plant managers are looking to their automation systems to keep track of energy consumption and to reduce overall use. In some cases, it’s a matter of making the plant more efficient—and thus less of an energy hog—and in other cases, plants are integrating automation with heating, ventilation and air conditioning (HVAC) systems to measure and reduce energy consumption.

Plants are under pressure to reduce their energy consumption, and not just for cost savings. Whether it’s government regulations or simply being a good citizen, reducing carbon emissions has become important in just the past three or four years. “In renewable energy and efficiency, there’s a lot going on,” says Brian MacCleery, green technology engineer at NI.“The motivating factor is cost, but there’s a growing realization that being environmentally friendly and saving money go hand in hand. A kilowatt of power is a pound of coal. Saving kilowatts saves on emissions.”

Concerns about the environment may be as important as cost savings at this point. “If you read the press and listen to officials in the European Commission or Washington, it’s clear that politicians want less carbon emissions,” says Laurent DeMortier, president of the Energy Management Business at Alstom, a transport and energy infrastructure provider based in Washington D.C. “Spending less is not the only motive. Energy consumption savings is as much about the environment.”

One of the quickest ways to reduce energy consumption is to conduct an energy audit and make the plant’s facility more efficient. “Usually with a building, you have a building monitoring system. We interface to that system so we can optimize how the energy is used,” says DeMortier. “By merging control with the IT (information technology) in the building system, we can send signals to manage the building’s needs. If you have solar energy, you can program the system to switch to grid when the sun’s not out and switch to solar when the sun is out.”

Surging gremlins

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