Recovering to Reduce

Today’s ethanol producers are looking for ways to maximize their efficiency, cut costs and reduce their CI score. A Florida-based technology provider has found a way to help plants do all three by utilizing waste heat from DDGS dryer exhaust.
By Melissa Anderson | April 13, 2022

Superior efficiency is the hallmark of low-cost ethanol production. The industry’s top plants consistently achieve greater-than-average margins because they spend less and get more from each bushel of corn processed. Now, mounting incentives for carbon intensity (CI) reduction are boosting the efficiency motive for biofuel producers. And while lowering CI is more about energy reduction than cost cutting, Bioleap’s innovative Dryer Exhaust Energy Recovery (DEER) system helps producers do both, and more.

“The DEER system reduces ethanol plant energy use by over 20% and recovers [process] water, which reduces the plant’s need for freshwater,” says Wayne Mitchell, Bioleap CEO and founder. “There are no other shovel-ready technologies like this out there that provide this magnitude of carbon reduction.”

Mitchell says the idea for DEER came from ethanol plant energy audits, which identified the dryer system as a large user of energy where heat had not been recovered and integrated into plants. Half a dozen ethanol plants have already installed the DEER technology, drawn to its ability to meaningfully reduce their carbon intensity at an attractive ROI.

“While the quality of the energy available from ethanol plant dryers is relatively low grade, the DEER system was designed to recover and upgrade that energy into a form that is usable [and can] be recycled back into the plant’s evaporator system,” Mitchell says.

Each DEER system installation, which comes with process guarantees, starts with a high-tech facility assessment. The system’s physical integration begins with a 3D laser scan of all areas of the facility where DEER-related components will be installed. The 3D laser scan is extremely accurate in representing the existing facility, making the design and installation easier and substantially reducing the chances of unforeseen circumstances in the field. Taking approximately nine months from contract signing to system operability, DEER is designed to be a “valve in/valve out,” addition to an ethanol plant, allowing producers to bypass the system if necessary. That, however, has not yet been necessary.

“To date, once DEER is put into operation, no plant has opted to, or needed to, bypass it,” Mitchell says. “Tie-ins for DEER can be made during normal plant maintenance shutdowns, so there are no disruptions to the plant’s normal operations to install [the system].”

Thus far, DEER has been installed at (and in continuous operation at) seven locations across the Midwest, with two additional DEER projects currently under design/construction with start dates in 2022. The oldest DEER system has been in operation for five years, operating since May 2017 at Siouxland Ethanol LLC in Jackson, Nebraska.

Siouxland Ethanol first learned of Bioleap’s DEER system at the 2016 International Fuel Ethanol Workshop & Expo. Nick Bowdish, president and CEO of both Siouxland Ethanol and Elite Octane LLC,  located in Atlantic, Iowa, was in attendance. There, on the trade show floor, he spotted a sign signaling an opportunity to cut a plant’s natural gas consumption per gallon significantly.

“The Fuel Ethanol Workshop in 2016 was a key milestone in Siouxland Ethanol’s pursuit of lowering the carbon intensity of ethanol production,” Bowdish says. “Less than a year later, Siouxland Ethanol was the first corn ethanol plant in the United States to install and commission the DEER system. Nearly five years later, we are still as pleased with the system as the day we purchased it.

Bowdish continues, “The Bioleap DEER system is a good fit for any corn ethanol plant that produces DDGS, desires to lower its carbon intensity and is striving to be a low-cost producer.”

A prominent ancillary benefit of the DEER system, according to Bowdish, is that, for ethanol plants set-up with a package boiler and regenerative thermal oxidizer (RTO)—rather than a thermal oxidizer/heat-recovery steam generator (TO/HRSG)—the Bioleap technology acts like a wet scrubber in front of the RTO. The system helped Siouxland maintain peak production with an undersized RTO by removing carryover particulate that found a way past the DDGS dryer cyclones.

“Elite Octane commenced production in July 2018. After maximizing throughput of this facility with an additional fermenter, Bioleap’s technology was the first capital expenditure we made,” Bowdish says. “The DEER system came online at the end of 2021 and is meeting our expectations. The financial return has only improved since the time of making the decision, as natural gas prices have increased.”
Since its creation, the DEER has been upsized by more than 30% to allow for additional energy recovery, Mitchell explains. While the original DEER design was aimed at recovering energy into the ethanol plant evaporator system, several additional modules that work in conjunction with DEER have allowed it to recover more energy, which can be used in other areas of the plant: distillation, cook, slurry and liquefaction.

“After the advent of new add-on modules, such as our AHR-Side Stripper module and our SHARK (Slurry Heating and Reduced backset) module, several plants with existing DEER systems have purchased add-on modules and further increased their energy efficiency by 5 to 10%,” Mitchell says.
Bioleap characterizes the savings to an ethanol plant on a BTU-per-gallon level, which translates easily into cost savings based on natural gas expenditure before and after installation. On average, ethanol plants are saving 6,290 BTU per gallon of ethanol produced—and some are saving as much as 8,500. For plants that can monetize carbon reduction, the DEER system typically reduces the CI score of their fuel by three to four points, if not more. Also, with the reduction in freshwater requirements, water use savings can be found, depending on the plant’s water source and quality requirements. The latter two potential savings vary widely from plant to plant.

Ethanol plants that have installed the DEER system have reported experiencing minimal to no additional operating and maintenance costs. Mitchell says the only moving parts in the DEER system are pumps for moving water, which have been highly reliable. The net electrical impact of DEER is neutral to a slight savings post installation.

The DEER system itself does not have any seasonal variations in performance. The primary variable affecting the system’s recovery rates is the amount of energy available in the dryer exhaust, and there are some seasonal variations in the plant’s ability to utilize recovered energy from the system. “More energy is needed in the winter months as the raw materials are entering the plant at much colder temperatures,” Mitchell says. “This allows the DEER to supply additional recovered energy to offset the cold.”

Today, more than ever, ethanol plants across the United States are looking for ways to maximize their efficiency to cut costs, reduce CI and enhance revenue. Mitchell believes the best way to do all three is through reduction of energy usage, which also moves the industry toward a more sustainable future. With technologies like the DEER system, the industry is a step closer to getting there.  

Author: Melissa Anderson