Operations Illustrated: Alternative Energy Sources
Benefits of Renewable Energy
Finding alternative sources of energy makes sense from an environmental and a financial viewpoint. In spite of headway made in recent years, it’s an uphill battle fighting the public’s general perception of the aggregates industry as less than environmentally friendly. And energy costs are not going down.
One answer? Renewable energy. Because of their geographic location, some producers have been able to move toward renewable energy sources such as wind and solar power — both connected to and removed from the grid.
In 2006, CalPortland Co., based in Glendora, Calif., entered into a long-term agreement with Alite Wind, LLC, to supply power from eight 3-megawatt (MW) wind turbines at its Mojave Cement Plant. Installed in 2007, the 24 MWs of power generated by these turbines for the plant — up to 60 million kilowatts of power per year — is equivalent to the annual energy needs of more than 10,000 homes.
“The Mojave Cement Plant (north of Los Angeles in the Mojave Desert) is in one of the windiest areas in the country,” says Steve Coppinger, director of engineering services for CalPortland. He explains that, while there are other wind turbines on the property that are connected to the grid, the turbines supplying power to the Mojave Cement Plant are completely “behind the meter.”
“The plant is on the grid, but the turbines are behind the meter,” Coppinger says. “The energy the turbines produce amounts to about 35 percent of our needs, so we draw our additional energy from the grid. But everything we collect with these eight turbines reduces the energy we have to pull from the grid.”
The BoDean Co. of Santa Rosa, Calif., has also invested in renewable energy. In late 2010, its Mark West Quarry near Napa Valley began installation of solar panels that would allow the company to operate off the grid. On May 11, 2011, the Mark West Quarry held an official cutover ceremony, as the site became 100-percent solar powered.
“The area where the Mark West Quarry lies is far enough inland that fog creates a minimal impact,” says Bill Williams, BoDean Co. general manager. “While we do get rain in the winter; in the spring, summer, and fall — which is our largest production period — it’s dry and rarely cloudy.”
Unlike the wind turbines at the Mojave Cement Plant, the Mark West Quarry’s solar panels are connected to the grid. When the weather is cloudy, the plant may draw power from the grid. And when it is sunny, enough power is produced that the quarry can feed power back into the grid, even as it uses power for the plant. “It seems to balance out in what we draw from and feed into the grid,” Williams notes.
The ability to provide your own energy via renewable sources, such as wind, is driving some companies to set up energy systems “behind the meter.” In these situations, a portion of the energy needs for the site are delivered independent of the electrical grid — by way of a few wind turbines or solar panels. While the independent system may provide much of the energy for the site, it does not provide all of it. Additional energy needs are met from the grid.
If an alternative energy source has the potential to create more energy than a company needs, such as the solar panels pictured here, there is the option to remain connected to the grid, feeding back into it when surplus energy is created. Other times, if the alternative source cannot create enough energy to meet demand at the site, the company can still draw from the grid.
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