CO2 Monitoring: a New Grain Management Tool

The 2009 harvest, characterized as unusually late, wet and followed by a warmer-than-average winter, has raised grain quality concerns among grain handlers, processors and users across the country. Over the past decade, grain quality has been generally good and taken for granted, but faced with today’s grain condition challenges, grain elevator operations managers are looking for better ways to monitor their stored grain.

A joint research effort by Kansas State University, Purdue University and BinTech, with help from The Andersons, Inc., has answered their call. They’ve developed a new method of measuring grain quality by using CO2 readings as an early indicator for problems such as spoilage, mycotoxins or insect infestation. High CO2 levels indicate a problem because as grain decays and breaks down, it gives off heightened levels of CO2. The higher the level, the more deterioration is likely.

The research project, now in its 10th year, has resulted in the first-ever continuous CO2 monitoring system, BinTechCO2, which will be commercially available in June this year. Using this system can aid in making educated business decisions, such as when to move, process or sell grain.

K-State/Purdue/BinTech research project

Dr. Dirk E. Maier, Ph.D., P.E., professor and department head of grain science and industry at Kansas State University, initially began monitoring CO2 levels in 1998 on small 500-bushel-bins at Purdue University’s Post Harvest Research Center while serving as associate professor and extension agricultural engineer at Purdue. The first goal was to determine the smallest amount of CO2 activity that could reasonably be measured, and reveal what that activity represented in terms of grain spoilage in the structure.

“CO2 levels can be used as an early indicator of spoilage activity and we wanted to find out what the alert levels are — at what point should people take proactive grain quality management steps,” says Maier.

They found that cause for alarm occurs when the bin’s CO2 level reaches three to four times greater than the background CO2 level on a consistent basis. Generally, the background level for CO2 is around 400 ppm. Readings around 1,000 ppm indicate the bin should be watched; readings of 1,200 to 1,600 ppm means further investigation is required because there likely is a problem.

They also determined that a slow but growing background level can be indicative of an issue. For example, if the background level starts at 400 ppm and grows to 600 ppm and then 800 ppm over a span of weeks, it indicates there’s something at a low level going on in the bin, perhaps insect infestation.

In 2000, Bob Marlow, operations manager of The Andersons, Inc. Delphi, IN facility, located 20 miles outside of Purdue University, signed on to be a part of Maier’s study. The research team applied the same technology used on the smaller bins at Delphi’s 500,000-bushel-bins. Today, a total of 20 pilot facilities in Indiana and Kansas are participating in field work and producing data for the project every day.

Guy Fromme, P.E., founder and general partner of BinTech, Louisville/Boulder, CO, played an integral role in Maier’s research from the beginning by providing custom-made, permanently mounted CO2 sensors. Over time, the project answered basic questions regarding sensor placement in the bin, number of sensors required in the bin and how to design a sensor that addressed the air-entrained grain dust while having the desirable characteristics of low maintenance and low cost.

The result is BinTechCO2, the grain industry’s first commercially available fixed CO2 monitoring device that will be available for purchase this summer.

A new tool in the box

The most accurate way to describe BinTech CO2 is as a grain management tool. The system works with a small solar-charged control box that mounts on the bin roof. The control box collects and buffers in-bin data and sends that to BinTech’s secure central server once or twice per day.