ABB based its solution on the Organic Rankine Cycle technology that facilitates the transformation of gas heat into electricity.
Cement products manufacturing involves clinker-burning kilns that run temperatures up to 1500 degrees Celsius. While modern plants re-use most of the process exhaust heat for material drying, a significant amount of low temperature gas is vented through the stack.
ABB’s system takes the waste heat—even as low as 150 C—and generates power. “The recovery system allows us to produce 10.5 gigawatt hours of electrical energy per year,” says Markus Hepberger, the Holcim plant manager. “This corresponds to the demand for energy of approximately 2,000 households in Switzerland.” The waste heat produces enough operating power to make fossil fuels unnecessary for running the plant.
For decades, alternative energy sources were a great idea that just didn’t produce power at a rate to compete economically with traditional oil, gas and coal. That picture is changing rapidly. For one, fossil fuels used to be cheap. In recent years, oil costs have soared, gas prices have increased and coal has become a carbon-footprint problem.
These changes alone make alternative energy more viable, but a bigger change may be that the cost of alternative energy is coming down as the cost of fossil fuels is going up. Much of the cost reduction in alternative energy has been delivered by automation technology. Automation has brought down the price of producing energy from alternative sources. Automation has also brought down the price of the equipment—solar panels, wind turbines—needed to produce alternative energy.
Making it possible
Many believe that automation has made alternative energies possible, not just less expensive. Even if cost were not a factor, alternative energy needs to match the simple reliability of fossil fuels in order to be viable. Without automation, that wouldn’t be possible. “Alternative energy has been unpredictable. That’s why people have not adopted it. Advanced process control changes that,” says Marc Leroux, marketing manager for collaborative production management at ABB, in Cary N.C.
Automation can take the variances such as burning temperature levels out of alternative fuels and deliver consistency to the plant. “If you’re going to use alternative fuels or byproducts to run a plant at optimal rates, you’re going to use automation to offset the variances that you have in the fuel. This is the perfect application for advanced process control.”
Whether it is wind, solar, biogas or thermal, automation is playing a role in making alternative energy ready for prime time. “Clearly, automation makes alternative energy more efficient and more viable,” says Leif Eriksen, an analyst covering supply chain at Gartner Inc., in Stamford Conn. “In solar, it’s the ability to calibrate the solar banks and move and track the sun.” Eriksen also sees automation as critical to making wind power viable. “Automation is helping get the most out of wind energy, especially in the use of wireless sensors. Automation and wireless sensor technology help make the generation of solar and wind more effective and efficient.”
Alternative energy may soon be viewed as an inexpensive alternative to traditional energy sources. “We’re looking into the use of automation to help reduce the costs of alternative energy sources so they can compete with fossil fuels without the need for subsidies and incentives,” says Jamie Bohan, director of alternative fuels and energy at automation supplier Honeywell Process Solutions, in Phoenix. “The innovation in this area is around advanced sensing and control.”
Part of the way that automation can bring down the cost of alternative energies is to make the equipment less expensive to produce. “In wind, each turbine has about 8,000 parts, and somebody has to make that stuff—bearings, blades,” says Chuck Juda, renewable energy business development manager at Pepperl+Fuchs Inc., an automation supplier in Twinsburg, Ohio. “A lot of automation in the factories that make that stuff is helping to bring down prices.” He also notes that automated production at plants making solar panels has driven down the cost of producing solar power.
Chasing the wind
Wind is the key energy source for the Sotavento Virtual Power Plant in Galicia, Spain. The plant was designed by the Spanish energy company Gas Natural, in conjunction with the Galician Regional Government and Sotavento Foundation. The plant is tasked with assessing the suitability of using hydrogen as a storable form of energy in its gas state.
The plant itself is powered in part by the wind. All electrical power is generated by wind-power aero generators. Like most plants, Sotavento uses a collection of disparate control systems. Gas Natural brought in a system integrator to create an integrated supervisory system based on the Snap PAC System supplied by Opto 22, a Temecula, Calif.-based automation supplier.
The system is used to run the electrolyzers, compressors and hydrogen motor-generator units, as well as to integrate data from the wind generators. The system also provides level and temperature monitoring in the hydrogen storage area. The result is a plant that balances wind and hydrogen to produce a constant power level to Spain’s electricity network. The hydrogen is used to “top up” the power generation to fill in the variances in wind production.
Garbage has never been so useful as it is to Granger Electric, in Lanchester, Pa. The methane produced by decomposition in landfills is 23 times more potent than carbon dioxide. Granger uses wells to oxygenate the waste mass—expediting the decomposition process—and to trap the biogas before it can escape. Separators are then used to clean the gas by extracting methane from the remaining gas substance (carbon dioxide and trace elements).
One of Granger’s biggest customers is a major international food supplier located 13 miles away. The food plant uses Granger’s methane as a natural gas substitute to power its boilers. The biogas supplied by Granger is roughly half the cost of natural gas.
Granger and the food plant exchange gas flow data using Ethernet programmable automation controllers (PACs) supplied by Rockwell Automation Inc., Milwaukee. Granger is hardwired via a T1 phone line to the Rockwell PACs so it can send gas flow information back to Granger’s master PAC.
The food plant itself is spread out, so plant managers deployed radios supplied by ProSoft Technology Inc. Bakersfield, Calif., to communicate to the PAC. “The radios saved us on installation and simplified implementation,” says Joe DiFerdinando, an electrical engineer at Granger.
Coal to gas
Coal is the most plentiful fuel in the world. It’s also pure carbon. Yet one use of coal—gasification—shows promise in converting coal into natural gas or diesel fuel. “Taking coal, and rather than burning it, you gasify it. Heat and pressure strips away the nasty stuff you don’t want in the atmosphere,” says Al Novak, director of alternative energy industries at automation supplier Emerson Process Management, in Eden Prairie, Minn. “What you’re left with is a gas stream that can be turned into natural gas or diesel.”
Novak notes that Emerson is involved in developing coal gasification solutions. “We’re working with a company in South Korea, and they believe they can produce natural gas for half the price,” says Novak. “In China, they’re using coal gasification to make chemicals—coal to ethanol. The driver is cost reduction.”
Coal gasification is still in its infancy as an alternative energy source. “Wind and solar are well known and they use commercially available technology, but coal gasification is more experimental, especially if you want to do it with carbon capture,” says Honeywell’s Bohan. “It’s more for the future.” When that future arrives, coal gasification may provide the greatest promise of all the alternative energy sources, simply because coal is so plentiful.
Automation has provided the breakthroughs that alternative energies needed to become viable against traditional fossil fuels. Plants are finding that alternative energy is a realistic choice for power—in many cases, a preferable choice over traditional energy sources. Automation is at the heart of enabling alternative sources, both through enhancing the use of alternative energy and through making alternative energy product less expensive.
Perhaps the most promising energy solution of all is within an easy reach for automation—efficiency. If a plant can drive down its need for energy through efficiencies derived from automation, alternative energy becomes more viable. “Energy efficiency is overlooked because it is something people can do today. But I can’t overstate enough how important it is for industrial manufacturers,” says Bohan. “Plants can replace fossil fuels with coal gasification or steam or biofuels and make it work because software has helped reduce their energy consumption.”
March 2011, Related Feature - Going for the Wind Above the Turbines
To read the feature article, visit www.automationworld.com/feature-8388
June 2007, Related Feature - Solar Energy Provides Green Fuel
To read the feature article, visit www.automationworld.com/feature-3290