POET Uses Zero-Liquid Discharge System to Reduce Ethanol's Water Demand
photo: Drew from Zhrodague via flickr
With the water required to make corn ethanol again coming into question, this one's apropos: Ethanol producer POET has announced that its Bingham Lake, Minnesota biorefinery is using a new zero-liquid discharge process that cuts back on the water intensity of the ethanol production process:23% Less Water Required
Prior to the zero discharge process the facility used on average 3.42 gallons of water to make one gallon of ethanol. Afterwards that has been reduced to 2.64 gallons of water per gallon of ethanol—a reduction of 23%. Not as much as a drastic reduction as some of POET's promotional materials would have you believe, but a very sizable reduction nonetheless.
Zero-liquid discharge means pretty much what it sounds like: No water is discharged from the plant into the environment in liquid form—steam still leaves the plant.
Keep in mind that this reduction in water usage is only at the production stage and doesn't take into account water required in other areas of ethanol production (growing the corn, etc...)
Good PR or Just Fortuitous Timing?
I don't know if it's PR damage control—a recent article in Environmental Science & Technology examines the water embodied in ethanol in the US—or just coincidence (intuitively I favor the former), but POET is also taking the opportunity to point out other ways that water usage is limited at its other plants.
At one plant in Iowa, most of the water in the cooling process is obtained from a nearby waste water treament plant; all of the water at its Portland, Indiana location is recycled from a nearby quarry; at the Big Stone, South Dakota refinery, 80% of its water comes from cooling ponds at an adjacent power plant and discharged back to the power plant.
More: POET Biorefining
36 Gallons of Water per Mile: Corn Ethanol Uses More Water Than Any Other Biofuel
Ethanol Mandates: The Single Most Misguided Agricutural Program in Modern American History
Common Biofuel Myth: Corn-Based Ethanol To Blame for Global Food Shortages
So Thirsty: Corn Ethanol Uses Up To 300% More Water Than Previously Thought