Just as farmers are determined to reduce the footprint of their operations, ethanol plants are relentless in their efforts to cut water usage. Thanks to technology and some oldfashioned ingenuity, many plants are trimming their usage of water by one-third or more.
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And that’s no simple task, considering water remains vital to ethanol production. It is used for the boilers and the heating process, and plays a key role in cooling the operation, primarily in fermentation and distillation. Water is also used in each plant’s slurry process for corn.
“We really have tried to optimize our water usage in the plant,” says Erin Heupel, Lead Environmental Engineer for Sioux Falls, S.D.-based POET Design and Construction. “When we site a plant, we look at alternative water resources to supply those plants.”
POET biorefining facilities in Portland, Ind.; Big Stone, S.D.; Bingham Lake, Minn.; and Corning, Iowa, are among those that have utilized alternate water sources. Each plant is tapping into sources that would typically be unlikely candidates for drinkable water.
A UNIQUE PARTNERSHIP
In 2006, when Portland, Ind., residents learned a POET biorefining plant was coming to town, there were two immediate reactions: excitement and concern.
People wanted to know exactly how the plant would affect this community of 6,200 people, recalls Portland Mayor Bruce Hosier. One of the public’s chief concerns had to do with the area’s groundwater supply.
“There was some concern as to how the plant’s water needs would impact that particular area,” Hosier says. “That was pretty much resolved when they were able to partner with the stone quarry.” The new plant announced that it had plans to use quarry water instead of groundwater.
POET Biorefining — Portland pipes water from the Portland-based Meshberger Brothers Stone Corp. quarry, located a quarter-mile away. Water that was previously channeled down the Salamonie River in order to make room for quarry operations is now routed for use at the plant. Water is then fed into a 10-milliongallon retention pond constructed by POET. Beyond that, all that is required is for the water to run through a filtration system before entering the ethanol plant. “The water that comes from the quarry covers 100 percent of our [production] needs,” says Greg Noble, General Manager of POET Biorefining — Portland.
Hosier says the plant is well respected by residents, particularly because the end result was exactly what POET officials promised during the planning process.
“It was a wonderful opportunity for a partnership to develop. It was environmentally friendly and didn’t have any adverse effects on the wells in the area,” he says. “Sometimes you have to think outside the box. Here, we have a quarry dumping hundreds of thousands of gallons of water per day into the river. POET was able to tie it together, along with the quarry, to form a terrific partnership that works for both entities.”
WASTE NOT, WANT NOT
Ethanol plants don’t use as much water as one might think.
In 1998, it took 5.8 gallons of water to process a gallon of ethanol. In less than a decade, technology has cut that amount nearly in half. Because POET recycles all ethanol process water, its plants require about three gallons of water per gallon of ethanol, which is below the industry average of 3.5 gallons. Of the water taken into the plant, the majority is returned to the environment through steam to the atmosphere or environmentally safe surface water. Only a small percentage of the water is actually consumed in the ethanol process.
By comparison, it takes 1,851 gallons of water to refine one barrel of oil, 24 gallons of water to produce a pound of plastic and 62,600 gallons of water to produce one ton of steel, according to the U.S. Geological Survey.
REDUCE AND REUSE
When the city of Corning, Iowa, built its wastewater plant several years ago, no one imagined there would ever be a use for the runoff. It certainly could not be used for drinking, laundry or bathing. Consequently, every day, a large amount of treated water from the plant was simply released into a nearby river.
All of that changed last year with the start-up of POET Biorefining — Corning. The ethanol plant reuses the water from the treatment plant instead of taking additional fresh water from the community.
Richard Hogan, who chaired the Corning Municipal Utilities board at the time, says the wastewater idea was born of necessity. The city wasn’t sure the water plant could handle the ethanol plant’s water needs.
“The biggest concern from the community was whether we would have enough water left over in case another industry was to come along,” Hogan says.
Ultimately, the decision was made to make water previously piped into a nearby river available for the plant’s cooling tower. The net result is that far less treated water is required from Corning’s water system.
“It turned out to be a win-win situation for both us and the city,” adds Greg Olsen, General Manager of POET Biorefining — Corning. “The city wins because it doesn’t have to treat 100 percent of the water we get. We win because we don’t have to worry about a supply interruption, and we know that it is good for the environment.”
‘UNWANTED’ RESULTS
Like the plants in Portland and Corning, the water plan at POET Biorefining — Bingham Lake involves water that, until now, was essentially unwanted.
The plant is working on a plan to take advantage of an aquifer that runs below the town’s landfill. Because of concerns of possible leachate from the landfill, it was never considered a source for drinking water.
As it works to develop the alternate water source, the decade-old plant will continue to tap the Windom, Minn., water system, five miles away. The concern at Windom is similar to that in Corning: The wells are operating over capacity.
[Optimal Efforts]
The new water option arose three years ago when the aquifer was discovered by Red Rock Rural Water, a regional water supplier based in Jeffers, Minn. Dominic Jones, Manager at Red Rock Rural Water, called Dave Easler, General Manager at POET Biorefining — Bingham Lake, to ask if the POET plant would be interested in developing this water source. Easler agreed that, while it may not be good for consumption, it is an ideal source for industrial water.
POET then spent six months researching the water source, and ordering test wells and lab reports. Once that was finished, it worked more than two years to get the necessary state permits for the project.
Plans are now in motion for POET to construct a water treatment plant at a site a half-mile from the landfill and nine miles from POET Biorefining — Bingham Lake. The pipe leading from the water plant to Bingham Lake is almost complete. Easler estimates the plant will invest about $2.2 million for the entire project.
“We anticipate they will start the project as soon as the ground thaws in the spring and finish sometime in October,” Easler says. “Once the water treatment plant is operational, the water will serve the entire needs of the ethanol plant.”
Ultimately, the investment will save 140 million gallons of drinkable water per year for Windom’s water supply.
CONSERVING THE SITUATION
Water conservation is nothing new for POET Biorefining — Big Stone. Since 2002, the plant has been using recycled water from the cooling ponds at the Big Stone Power Plant, a coal-fired electricitygenerating plant located a half mile away.
“About 90 percent of our water comes from the Big Stone Power Plant’s cooling ponds,” says Blaine Gomer, POET Biorefining — Big Stone General Manager. “We pipe the cooling pond water to our plant and run it through a filtration process to clean it up. Then we use that filtered water in our processes.”
The remaining 10 percent of the plant’s water comes from the Big Stone City Municipal Water. That water is used for boiler operation and other potable water needs.
Gomer says recycling the water from the power plant’s cooling ponds is an ideal situation. “The water from the cooling ponds comes from excess lake water off of Big Stone Lake,” he says. “The plant fills the ponds in the spring during the snow run-off.
“We take [the water], clean it up, and whatever we don’t use, we will send back. It is a recycling process,” Gomer says.
FULL STEAM AHEAD
As America’s ethanol plants grow more technologically advanced, we will continue to see more innovations in reduced water use, as well.
“A major premise of ethanol is to help improve our environment,” Heupel says. “It is a green process to start with, and any way we can find to increase the efficiencies and reduce the usage of water only enhances the green product.
“I think most plants take it seriously and want to be good stewards of our environment.”
To learn more about the water usage process at POET, visit poet.com/sustainability
