How High Temperature Fermentation Impacts Ethanol Yields

Fermentation is like tuning a high-performance engine. Every part—from the fuel mix to the temperature gauge has to be just right. But what happens when the engine overheats? In ethanol plants, high temperature fermentation can throw the whole system off balance. Let’s look under the hood and troubleshoot the most common issues that stall your fermentation.

High-temperature fermentation brings a variety of benefits to fuel ethanol production, including increased yields, faster fermentation times and reduced cooling costs. However, high temperatures can also increase the toxicity of ethanol to yeast cells—inhibiting fermentation. Ensuring the right thermotolerant yeast strain and conditions are key for optimal performance but there are additional steps ethanol producers can take to potentially limit the negative impact. Explore our top three tips for managing high temperatures below—both before and during fermentation.

Three top tips for high temperature fermentation

Increase the probability high temperature fermentation will finish

If you anticipate that fermentation is going to reach temperatures above 95°F, there are a few ways to increase the probability that the fermentation process will finish—without reducing the temperature. These methods can either be used individually or in combination depending on your preferences. These include adding additional nitrogen, decreasing the dry solids (%DS) percentage and staggering the enzyme loading.

Improve monitoring

In high temperature fermentations, keeping a close eye on the data is crucial. This helps you to characterize the high temperature excursion and see if it was for an extended period or if the temperature is still rising, for instance. It’s also an opportunity to check the cell counts and viability of the yeast, making any necessary adjustments or additions.

Maximize heat exchange efficiency

Since cooling water is a finite resource and every fermentor has a specific heat exchange capacity, maximizing efficiency in ethanol plants is essential. This means minimizing the amount of heat that needs to be handled in the cooling tower and reducing wastewater.

Remember, in high temperature fermentations, little can be done after 15-24 hours to make a significant difference —but there are a wide range of methods that can be used before or during fermentation to help manage this process. For more detailed advice on each of our top tips.