Combined Heat and Power Partnership
Dry Mill Ethanol
- The CHP for Ethanol Facilities Fact Sheet summarizes the technical, economic, and environmental benefits of using CHP to provide electricity and steam for a dry mill ethanol production facility. Download a PDF version (4 pp, 275K) to print and share.
- A new report on The Impact of Combined Heat and Power on Energy Use and Carbon Emissions in the Dry Mill Ethanol Process (PDF) (13 pp, 170K) compares energy requirements at state-of-the-art conventional and CHP-powered ethanol production facilities to show energy savings and greenhouse gas emissions reductions resulting from CHP. The report compares natural gas-, coal-, and biomass-fueled ethanol production facilities.
- EPA's CHP Partnership wrote an article for District Energy Magazine (PDF) (9 pp, 350K) that details innovative joint ownership CHP projects between ethanol facilities and local utilities.
- EPA's CHP Partnership team has conducted a preliminary evaluation of the ability of CHP systems to serve as VOC oxidizers for ethanol facilities. To learn more, download the white paper: Integration of VOC Destruction and CHP in the Ethanol Industry (PDF) (13 pp, 64K).
An Innovative Solution
An innovative partnership between an ethanol plant and rural electric utility is located near the city of Macon, Missouri, where a CHP system was built in 2003. A partnership was forged between the Macon Municipal Utilities (which purchased a natural gas-fired 10 MW combustion turbine) and Northeast Missouri Grain, LLC (which built the CHP system's housing and control building).
Each organization pays for half of the cost of the natural gas that powers the turbine. The project supplies 10 MW of electricity to the utility at 50 percent lower natural gas costs than traditional generation capacity. The project provides nearly 60 percent of the plant's steam needs for ethanol production, while reducing its natural gas costs by 20 percent per year.
The CHP project requires approximately 25 percent less fuel than the typical system of onsite boilers and purchased electricity, and based on this comparison, reduces CO2 emissions by an estimated 30,200 tons per year. EPA recognized the energy and environmental benefits of this project by presenting Macon Municipal Utilities with a 2007 ENERGY STAR® CHP Award.
Analysis by the EPA's Combined Heat and Power (CHP) Partnership shows a strong technical fit for CHP in ethanol facilities and a potential reduction of approximately 15 percent in the energy intensity of dry mill ethanol production. Given the massive construction activity in this sector, the time is right to integrate CHP into new and expanding dry mill ethanol facilities and to ensure that CHP is part of the base design for future cellulosic ethanol biorefineries.
CHP can be a compelling application for ethanol production facilities because:
- Energy is the second highest cost of production.
- Electric and steam demands are large and coincident. For a 15 to 50 million gallon per year (MGY) facility:
- Typical power demand is 2 to 6 megawatts (MW).
- Typical steam use is 40,000 to 150,000 pounds per hour (lb/hr).
- Electric and steam profiles are relatively flat.
- Facilities usually run 24 hours per day, seven days per week.
As of May 2008, more than 145 dry mill ethanol plants are operational in the United States, with a total capacity of approximately 8,500 MGY, and an additional 61 plants are under construction or are undergoing an expansion, with a collective capacity of approximately 5,000 MGY. EPA has been providing outreach and technical assistance to the ethanol industry for the past five years to raise awareness and assist ethanol developers in implementing CHP. Seventeen dry mill ethanol plants now use CHP to generate steam and electricity reliably and efficiently on site; another seven are under construction.
A variety of CHP system configurations are available for dry mill ethanol facilities:
- Boiler/Steam Turbine CHP: Proven technology fired by solid fuel, including coal, biomass, or cofiring. Sized for thermal loads, may limit electrical production. If coal-fired, may pose permitting challenges.
- Gas Turbine CHP: Requires supplemental steam when the turbine is sized to meet the facility's electric load. By adding supplemental firing to the system, it can be sized to meet electric and thermal loads.
- Biomass CHP With Gasification: Least expensive fuel, but the technology is capital-intensive and still being commercialized. Considered "green" electricity if sold; tax credits could be available.
- Integrated Volatile Organic Compound (VOC) Destruction: Produces power with steam from thermal oxidizer or incorporates VOC destruction in turbine or boiler systems; can minimize compliance costs.
- Ethanol/Utility Partnerships: Public power companies and rural electric cooperatives are engaging in joint CHP ownership arrangements with ethanol facilities as thermal hosts in states including North Dakota, Missouri, and Kansas. For details on these win-win projects, see the CHP Partnership's article in District Energy Magazine (PDF), (8 pp, 118K).
The Partnership works closely with The Midwest CHP Application Center to promote CHP in ethanol plants. The Midwest CHP Application Center has developed a number of case studies for CHP at ethanol plants.
The CHP Partnership has presented at numerous workshops and conferences to promote CHP at ethanol plants.
- 2007 Biofuels Workshop & Trade Show - Eastern Region, November 2007 (PDF) (19 pp, 249K) highlights the emergence of CHP facilities that are jointly-owned by utilities and ethanol production plants. Describes the economic benefits of these partnerships–including reduced equipment, operating, and fuel costs–and outlines some popular business models.
- 2007 Fuel Ethanol Workshop & Expo, June 2007 (PDF) (19 pp, 249K) focuses on the significance of CHP in reducing overall energy use and lowering the carbon footprint of the dry mill ethanol process. Also compares net energy consumption between different CHP fuel sources (e.g., coal, biomass, or natural gas).
- 2006 Fuel Ethanol Workshop & Expo, June 2006 (PDF) (14 pp, 171K) describes the voluntary CHP Partnership, depicts typical CHP efficiency for ethanol plants, and outlines a business case for incorporating CHP into the ethanol industry. Includes calculations describing potential fuel savings for natural gas-fired ethanol plants.
- Governors' Ethanol Coalition, February 2006 (PDF) (16 pp, 692K) describes CHP for the ethanol industry; outlines CHP basics and the technology's efficiency and environmental benefits; and features the Russell, Kansas, ethanol plant and its partnership with a local municipal utility.
- Sixth International Decentralized Energy and Cogeneration Conference and Exhibition, October 2005 (PDF) (40 pp, 1.3 MB) outlines the growth in the ethanol industry, including the effect the Renewable Fuels Standard will have on the industry, and how CHP can generate significant cost savings for ethanol production plants. CHP technology and system options are also described.
- Governors' Ethanol Coalition, March 2005 (PDF), (26 pp, 521K) supplies information on the ethanol industry and how CHP is an excellent fit for ethanol businesses. Also includes diagrams and descriptions of CHP technology options appropriate for installation at ethanol plants. Briefly describes some of the policies that states can adopt to improve adoption of CHP by the ethanol industry.