By Steve Murphy and Mike Siefert, Edited by Margaret Cook
We sat down with industry experts Steve Murphy, General Manager of POET Biorefining – Laddonia, and Mike Siefert, Director – Generating Assets for the Missouri Public Utility Alliance, to learn more about CHP applications in the agricultural sector.
Steve Murphy: Combined heat and power, also known as cogen or CHP, can provide a variety of facility types with resilience, lower operating costs, and reduced environmental footprints. When paired well, it can benefit the facility and the surrounding residents. POET Biorefining partners with Missouri Public Utility Alliance to provide power to Missouri residents through the Laddonia CHP turbine. POET’s biorefining facility produces ethanol from local corn.
Mike Seifert: The CHP facility uses waste heat from the biorefining process to generate electricity. The turbine produces more power than the bio-processing plant consumes and sends that power to the grid for Missouri utility customers. Here we discuss some of the benefits of this CHP use case.
Steve Murphy: The Laddonia CHP turbine produces more than double the electricity that the bio-processing plant consumes. This extra electricity is exported to the grid and provides another source of reliable baseload energy generation for Missouri and the local area. Both the bio-refinery and the turbine operate 24/7, so this high efficiency system is an ideal complement to intermittent solar and wind generation in rural areas.
Mike Seifert: Missouri residents save on both their electric bill and when filling up their gas tank. The cost for natural gas that fuels the CHP system is split between the utility and the bio-processing plant based on the efficiencies of the CHP system. As a result, electricity is produced at a lower cost, and the biofuel that replaces gasoline is also produced at a lower cost. The capital cost to build and install the system was also split. This savings is even more important as energy prices climb. Gasoline mixed with ethanol is a hedge against volatile global oil markets. Based on fuel prices June 6, 2022, 113 octane bioethanol is selling for $1.50/gallon less than gasoline before taxes and delivery costs. Customers are also supporting local farmers and jobs by buying locally made products, using locally grown corn.
Steve Murphy: Bioethanol has many uses. Bioethanol can be used for pharmaceutical uses, such as natural hand sanitizers and disinfectants, cough syrups, or as a solvent for other medications; for beverage grade consumption; as a fuel for cook stoves in place of propane, wood, or dung;i or as a high-octane gasoline additive. Ethanol is 113 octane and helps to lower the cost of gasoline, especially in a volatile global market.
Mike Siefert: The Laddonia facility helps to reduce greenhouse gases by displacing power generation from other fossil fuels. It also benefits from CHP’s high efficiency, reducing the amount of natural gas needed for each kilowatt-hour of electricity generated.
Steve Murphy: A few POET bioethanol plants also use solid fuel boilers or landfill gas rather than natural gas. Long-term, there are projects looking at anaerobic digesters using manure to produce methane that could then be used in place of fossil fuel natural gas.
Additionally, ethanol produced in POET’s biorefining is a lower carbon intensity than traditional gasoline. Bioethanol has been shown to have a 46% reduction in greenhouse gases compared to gasoline on average. CHP and bioethanol are available today for legacy vehicles already on the road. Ethanol is a cheap, clean way to make premium high-octane fuels. Since ethanol’s chemical structure has an oxygen molecule, it burns much cleaner than aromatics like benzene and toluene that are other options to boost octane. The extra oxygen in renewable bioethanol helps to reduce soot and incomplete combustion that creates other air pollutants in addition to CO2. Hybrid technology paired with high-octane bioethanol fuels like E30 (30% bioethanol at 93 octane) can reduce greenhouse gases compared to traditional gasoline vehicles.
The Laddonia site purchases approximately 28 million bushels of corn to produce 80 million gallons of biofuel for the corn starch along with corn oil, animal feed, and liquefied CO2 from the rest of the kernel. Mike Siefert: Since wind turbines, solar panels, and transmission lines often involve farmland it is important to get farmers onboard with greener energy options. Bioprocessing facilities that help stabilize crop prices and farm incomes help get farmers more interested and open to allow some land to be allocated for other renewable energy in addition to renewable liquid fuels.
Steve Murphy: Reducing waste is important to the Laddonia facility. CHP is key to this mission as it helps reduce waste heat. POET also uses 100% of the corn kernel. The starch is fermented for bioethanol production. The fat, fiber, protein, minerals, and nutrients left over are sold as corn oil for biodiesel or distillers’ grains for animal feed. Nothing is wasted.
POET also recycles a lot of heat and energy using heat exchangers in many locations to reduce the need for incoming energy. POET also strategically reduces the need for heat through use of enzymes. Older technology uses a “cook” process to break down the starch to sugars and then cools it. Instead, POET uses enzymes to break down the starch to glucose for the yeast to consume in a process called “cold cook.” This strategy eliminates the need for the heating and cooling step, reducing energy use in fermentation.
Finally, POET uses wet scrubbers to recover any ethanol vapors that come from fermentation or other areas of the process. The captured water and ethanol are recycled back into the process.
*This interview was edited for clarity.
Steve Murphy has been the General Manager of POET Biorefining – Laddonia for the last 12 years and also had dual responsibility for POET Biorefining – Macon for 5 years (2013-2018). POET is the largest bioethanol producer in the world with 34 bioprocessing plants in the Midwest that produce approximately 3 Billion gallons of biofuel annually. These sites also produce other bioproducts – distillers grain animal feed, corn oil, and liquefied CO2 from the same corn that produces ethanol. The two POET plants in Missouri produce over 130MM gallons of biofuel annually and 25MWH of electricity using CHP in 24/7 operation. Prior to POET Steve worked in the automotive industry for 21 years for a urethane foam seating supplier and has a BS in Chemical Engineering from the University of Missouri – Science and Technology (Rolla).
Mike Siefert is the Director – Generating Assets for the Missouri Public Utility Alliance (MPUA). He has over 35 years in the municipal electric utility industry with primary emphasis on power plant management, operations & maintenance, compliance and managing capital improvement projects. Mike joined MPUA in 2012 after a long career with the municipal electric industry in Florida. He oversees the generation asset portfolio for MPUA-MJMEUC which includes several large coal fired generation units, a large combustion turbine/combined cycle plant, a combined heat and power plants (Laddonia and Macon), a peaking plant consisting of two small natural gas fired combustion turbines and recently eleven (2.5 MW) and one (11.15 MW) Solar Farms. In addition, he supports the MPUA-MJMEUC members with their in-house generation resources, providing technical support and assisting with Southwest Power Pool generation costs. Mike has a Bachelor of Science Degree in Mechanical Engineering Technology from Southern Illinois University.
Margaret Cook, PhD is a research associate at HARC. Learn more.