Ethanol producer Mid-Missouri Energy achieves energy savings while increasing production through advanced process control technology.
In his January State of the Union address, President George W. Bush called for an increase in U.S. production of alternative fuels to 35 billion gallons a year by 2017, or nearly seven times current U.S. capacity.
That prospect—part of a Bush plan to reduce U.S. gasoline consumption by 20 percent over the next 10 years—would seemingly bode well for U.S. ethanol producers. But at the same time, the rising price of corn, ethanol's primary feed stock, has been cutting sharply into ethanol plant margins. "A year ago, we were often paying less than $2 a bushel for corn, but we've paid up to $4 here recently. So the price of corn has doubled," says Chris Wilson, plant manager at Mid-Missouri Energy Inc., a farmer cooperative-owned ethanol producer in Malta Bend, Mo.
The higher corn prices, along with general energy price volatility, are keeping the pressure on ethanol producers such as Mid-Missouri to be certain that their plants are operating as efficiently as possible.
Mid-Missouri took a big step in that direction last summer, when it installed an advanced process control (APC) application from Pavilion Technologies, an Austin, Texas, software provider. During a five-month period from April through August, Mid-Missouri installed Pavilion's Ethanol Dryer Control application, one of four modules offered by the vendor for use in ethanol plants.
The Dryer Control application relies on model predictive control (MPC) technology to optimize the process of drying the residue mash, called stillage, which is extracted from the distillation columns that produce alcohol from fermented corn mash. When dried to customer specification, the stillage is converted into what is called dried distillers grains with solubles (DDGS). This material is sold as a high-protein livestock feed ingredient, as a by-product of the ethanol production process.
The MPC technology uses a reference model of the drying process to monitor about 30 different variables to predict future process behavior and calculate an optimum set of control moves, based on real-time sensor data. The same technique is applied to associated evaporators. The resultant commands are fed back every 30 to 60 seconds to Mid-Missouri's Siemens APACS distributed control system (DCS).
Compared to Mid-Missouri's previous manual control method, the Pavilion application affords much tighter control, minimizing natural gas use in the dryers, as well as steam production for the evaporators, both of which save energy, says Miller. In the Mid-Missouri process, flash steam off the evaporators is also used to drive the distillation process, a step that is likewise optimized by the Pavilion application.
"If you run your distillation columns too cold, you will actually lose alcohol at the bottom of your columns, and that can never be reclaimed," Miller explains. Based on data from temperature sensors in the columns, the Pavilion application " allows us to run a real tight control where we're not overinducing steam or energy into our columns, but we're putting in just the right amount to keep product from being lost out the bottom," he says.
After about six months of operation, Miller says he has been pleased with the results produced by the Pavilion technology. Benefits from the application " appeared almost instantly" after installation, in the form of improved plant controllability and easing of the control burden on operators, he says. Other benefits also quickly became apparent, he notes, including improved consistency of product and increased plant throughput.
In the end, Miller says the application is saving Mid-Missouri Energy about 2 percent on energy costs, while increasing ethanol production by about 6 percent. In all, the co-op expects the Pavilion application to produce benefits in excess of $3 million annually, he adds, based on 2006 ethanol market prices.
In fact, Mid-Missouri is now moving ahead with a project to install Pavilion's full ethanol plant solution. That package, known as the Pavilion8 Ethanol Control Solution, includes modules that apply the same kind of MPC techniques to control of the distillation, water balance and fermentation processes, in addition to the drying process. Installation began last November, and is expected to be completed later this year.
The Mid-Missouri plant—which had a nameplate capacity of 40 million gallons of ethanol per year when it began operations in February 2003—is now producing at a rate of 50 million to 55 million gallons per year, says Miller. And one goal of installing the plant -wide Pavilion solution is to push that capacity to a consistent 60 million gallons per year. "I believe that's fully feasible," says Miller. " And we're now putting in the groundwork to make that possible."
TopEthanol isn't new. Henry Ford originally designed the Model T to run on the corn-based fuel, which currently accounts for roughly 3 percent of the nation's fuel consumption. Researchers at the University of California, Berkeley, say, however, that ethanol could replace 20 percent to 30 percent of fuel usage in the United States in just a few years—in part through cars converted to burn a mixture of ethanol and gas.
And so, as the country faces the dual dilemmas of oil dependence and global warming, leaders, including President Bush, are touting ethanol as a possible fuel of the future—and ethanol producers such as Tom Branhan are turning to IT to help them boost production.
Branhan is CEO of Glacial Lakes Energy, which operates an ethanol plant in Watertown, S.D. His company started using predictive control software from Pavilion Technologies about a year ago to help boost production and reduce the amount of natural gas used to run the plant. Since then, the company—which converts more than 17 million bushels of corn per year into 50 million gallons of ethanol—has increased production by as much as 10 percent while cutting its natural gas usage by up to 3 percent. " Adding computer control to our production process has allowed us to stay ahead of the curve," Branhan says.
Even though the basic technique used to make the fuel—distilling corn to make alcohol—hasn't changed much in a century, the process of producing high-grade ethanol can be tricky, Branhan points out. The corn is ground up and cooked, and the resulting starch is mixed with water to form a mash. By adding yeast, the mash is fermented and then pumped into a distillation system where the manufacturing process is completed. Throughout the process, producers need to monitor moisture levels, air flow and other variables such as the flow of natural gas that powers the plant's machinery.
By using control technology, ethanol producers can more effectively monitor these variables and make data visible to plant operators, Branhan says. For example, the computerized system allows Glacial Lakes' plant operators to more closely analyze the amount of water in the ethanol. They can then take steps to maximize the water content in the fuel, enabling greater production.
Predictive control technology was first used in oil refineries in the 1970s and is now used in petrochemical plants as well as power plants and paper mills. Tom Fiske, a senior analyst at ARC Advisory Group, says that by building control technology into plans for new ethanol plants, producers can be sure that they will be operating efficiently.
"The ethanol industry is still young,"observes David Culver, director of operations at Glacial Lakes. And greater automation, Culver adds, will help this industry face growing demand for its product.
TopWhat can one person - you, for instance - do to reduce pollution, decrease America's dependency on foreign oil and stimulate our economy? Use ethanol. Buy vehicles that run on ethanol. Ask your gasoline distributor to stock and clearly label gasoline pumps that feature ethanol.
You can have a voice. You can make an impact. You can vote with your dollars. You can do your part to promote the increasing use of renewable fuels.