Ethanol production in the United States began to take off in the late 1970s and early 1980s, when oil prices surged, and the country sought to reduce its dependence on foreign oil. The U.S. government responded by enacting economic policies to promote the production and use of renewable fuels, including ethanol.

In addition to economic policies that included tax incentives, the U.S. government also established the Renewable Fuel Standard (RFS) in 2005, which mandated that a certain amount of renewable fuel, including ethanol, be blended into gasoline each year. This policy has continued to drive demand for ethanol and has helped to make it a major industry in the United States.

According to the Renewable Fuels Association, there are currently more than 200 ethanol biorefineries operating in the United States, with a total annual production capacity of over 16 billion gallons. In 2020, the industry produced over 13 billion gallons of ethanol, making it the largest producer of renewable fuel in the country.  The industry also contributes significantly to the U.S. economy. According to a study by ABF Economics, the ethanol industry supported nearly 350,000 jobs in 2020 and generated over $43 billion in economic activity.

Moreover, ethanol production has environmental benefits, as it can help reduce greenhouse gas emissions and improve air quality. The industry has also helped to support rural communities by providing a market for corn and other agricultural crops, and by providing jobs and economic opportunities in these areas.

The ethanol industry is subject to a number of environmental regulations aimed at controlling pollution and reducing emissions of volatile organic compounds (VOCs). VOCs are a group of chemicals that can have harmful effects on human health and the environment, and they are emitted during the production and use of ethanol.  During ethanol production, various gases containing VOCs are produced, such as methanol, ethanol, acetaldehyde, and acetic acid. These gases are harmful to the environment and human health if released into the atmosphere.

Air Pollution Control Solutions for Ethanol Production

One way that the industry controls pollution and VOC emissions is by using advanced pollution control technologies, such as regenerative thermal oxidizers (RTOs) and thermal oxidizer (TOs), which are used to control emissions from ethanol production processes. Both of these technologies are designed to destroy VOCs and other air pollutants by using high temperatures to break down the pollutants into less harmful compounds before they are released into the atmosphere.

Both thermal oxidizers and regenerative thermal oxidizers (RTOs) are types of pollution control technologies used in the ethanol industry to control emissions of volatile organic compounds (VOCs) and other air pollutants. However, there are some key differences between the two technologies that can influence their use in different ethanol plants.

Thermal Oxidizers in an Ethanol Plant:

Thermal oxidizers, also known as afterburners, are simple combustion devices that use high temperatures to break down VOCs and other pollutants in the air stream. They work by mixing the exhaust gas with fuel and air, then igniting the mixture to burn off the pollutants before they are released into the atmosphere.  Typically, there is no heat exchanger in the TO, and as a result the exhaust gas is released at an elevated temperature.  One way to help capture the energy available in a TO exhaust stream is to use a secondary heat recovery system.  The energy available can be used to generate steam that is used in the plant.

Regenerative Thermal Oxidizers in an Ethanol Plant:

RTOs, on the other hand, use a more complex process to control emissions. RTOs consist of two or more chambers filled with ceramic media, which absorb heat from the exhaust gas as it passes through the unit. The heat is then used to preheat the incoming exhaust gas, which helps to reduce the amount of fuel required to maintain the high temperatures needed to break down VOCs and other pollutants.  Unlike the TO, the clean exhaust stream is released at a relatively low temperature.

RTOs vs TOs

The choice between using a thermal oxidizer or an RTO in an ethanol plant may depend on a variety of factors, such as:

  1. the plant’s production volume
  2. the types and quantities of pollutants emitted
  3. the available space and resources.

RTOs generally have a higher capital cost than thermal oxidizers, but they are also more energy-efficient resulting in lower operating costs.


Aftermarket Services for Ethanol Production

Ethanol producers place a premium on up-time and production with little to no interruptions.  As a result, oxidizer maintenance is critical.  Ethanol production can be considered a harsh environment for pollution control equipment, and regularly scheduled service visits help to ensure reliable operation of both TOs and RTOs.

The CMM Group has experience working with ethanol producers and understands the criticality of their air pollution control equipment.  We offer on-site engineering and service support, with flexible scheduling at competitive rates.  We work on all RTOs, whether it was sold by CMM or by another OEM.  Examples of typical aftermarket services that The CMM Group provides to the ethanol industry include:

  • RTO Valve Rebuilds – Whether poppet, butterfly, or rotary valves, The CMM Group can provide maintenance services to help ensure this critical component to all RTOs is functioning properly.
  • RTO Media Replacement – Due to the potential for particulate and harsh operating conditions, replacing the media in an RTO is likely to occur. CMM can work with ethanol producers to engineer a media bed replacement that will provide a balance between thermal efficiency and life expectancy of the media.
  • RTO Coldface Repairs – The coldface of the media is a critical component for reliable operation of the RTO. The coldface is responsible for supporting the ceramic media heat exchangers.  Due to the corrosive environment and organic particulate that is present in ethanol production, the coldface should be inspected and repaired as needed.  This item is typically addressed in conjunction with a media bed replacement.  CMM provides repairs and retrofits using robust designs and materials for improved operation.
  • Insulation Repairs / RTO Refractory – Whether in a TO or RTO, the internal insulation of the combustion chamber is an important part of the long-term health of the equipment in your Ethanol plant. An insulation failure can result in a “hot-spot” forming on the exterior shell of the equipment, which can lead to metal failure and expensive and time-consuming repairs.  CMM inspects RTOs and TOs internally as well as externally to find signs of refractory  By taking a proactive approach, insulation replacement will typically remedy and potential issues before they arise.
  • RTO Media Cleaning – Often times, cleaning or washing the RTO media beds can extend the life of the media. In conjunction with RTO bakeouts a media wash-out is designed to remove build-up in the media beds that restricts airflow through the RTO and reduces thermal efficiency and overall performance of the equipment.  CMM has experience performing media bed washouts in an efficient manner to reduce down-time and increase effectiveness of the wash-out.

Download Brochure: Engineered Solutions and Aftermarket Services for the Ethanol and Biofuels Market

The CMM Group offers reliable equipment and services that are designed to give ethanol producers peace of mind that their air pollution control equipment will be operational and meet the regulatory requirements that ethanol producers are required to maintain.  Learn more about our capabilities by contacting us.