Decarbonisation Technology May 2026 Issue

reducing dependence on fossil fuels, especially their use in higher blends ( US EIA, 2025 ). Other advantages of using bioethanol arise from its chemical properties, such as its high octane number,

Biogenic CO

Saccharication + yeast

Mash

Grains

Milling

Fermentation

Distillation

Bioethanol

Stillage

high evaporation temperature, and

Pelleting / thickening

Grain meal Sugar Yeast Biethanol

Drying

higher oxygen content compared to other fuels, which improve the

Evaporation

DDGS/Protein

Figure 2 Simplified process schema for bioethanol production

efficiency of combustion in internal combustion engines ( Kazmi, et al., 2025 ). Bioethanol production begins with the microbial or enzymatic fermentation of various feedstocks. Fermentation is a process in which microorganisms convert the sugars, primarily found in the starch portion of crops, into ethanol and CO 2 . During this process, the CO 2 produced is captured, which is the first value-added product of bioethanol plants. After fermentation, the resulting mixture, known as mash, a combination of solids and liquids derived from the feedstocks, proceeds to distillation and purification steps to separate and refine the final product: bioethanol. Only the starch portion of the feedstock is fermentable during this process, while other components, such as proteins and fibres, remain in the mixture. The remaining product after distillation is called stillage, which consists of leftover solid and liquid material. Stillage is a valuable byproduct because it contains proteins, fibres, nutrients, minerals, and oil. These components can be processed further to produce dried distillers’ grains (DDGs), a nutrient-rich feed ingredient used for animal nutrition (see Figure 2 ). The production efficiency of bioethanol refineries is impacted by challenges that arise during each process step and unit. Common issues include fouling, mineral deposition, complications with final product quality, and air pollution from hazardous air pollutants (HAPs). These problems can significantly impact plant efficiency, reduce production volumes, compromise product quality, and, in severe

cases, result in shutdowns and financial losses. While some challenges can be addressed by adjusting process conditions, most often they require the use of chemical treatments. While chemical products are commonly used as preventive measures, it is essential to ensure their compatibility with the overall process to maintain optimal performance and avoid unintended consequences. Kurita supports this industry with innovative chemistries designed to reduce air pollution, prevent deposits, enhance fermentation, and improve corn oil recovery to increase fuel ethanol manufacturer profitability. One example of a solution for reducing air pollution through chemical addition is Voxout 70C. This is a ‘fermentation-friendly’ CO2 scrubber chemical additive treatment, designed to help plants cope with HAPs when unable to meet compliance via mechanical scrubbing alone. Voxout 70C consists of ammonium bisulphite (ABS) plus a proprietary catalyst, which facilitates a quicker and more complete conversion of acetaldehyde, resulting in significantly lower levels of bisulphites being sent to fermentation. Case study: application of Voxout 70C in a dry-grind fuel ethanol plant In a case study conducted at a dry-grind fuel ethanol plant in the Eastern United States with a nameplate capacity of 100 million gallons per year (MMGPY), the Kurita team was brought in to reduce acetaldehyde levels to 10 ppmv. To achieve this, Voxout 70C was tested alongside