04-12-2012, 04:57 PM
Energy Efficiency Improvement and Cost Saving Opportunities for the Corn Wet Milling Industry
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ABSTRACT
Corn wet milling is the most energy intensive industry within the food and kindred products group (SIC 20), using 15% of the energy in the entire food industry. After corn, energy is the second largest operating cost for corn wet millers in the United States. A typical corn wet milling plant in the United States spends approximately $20 to $30 million per year on energy, making energy efficiency improvement an important way to reduce costs and increase predictable earnings, especially in times of high energy-price volatility.
This report shows energy efficiency opportunities available for wet corn millers. It begins with descriptions of the trends, structure and production of the corn wet milling industry and the energy used in the milling and refining process. Specific primary energy savings for each energy efficiency measure based on case studies of plants and references to technical literature are provided. If available, typical payback periods are also listed. The report draws upon the experiences of corn, wheat and other starch processing plants worldwide for energy efficiency measures. The findings suggest that given available resources and technology, there are opportunities to reduce energy consumption cost-effectively in the corn wet milling industry while maintaining the quality of the products manufactured. Further research on the economics of the measures, as well as the applicability of these to different wet milling practices, is needed to assess the feasibility of implementation of selected technologies at individual plants.
Introduction
As U.S. manufacturers face an increasingly competitive global business environment, they seek out opportunities to reduce production costs without negatively affecting product yield or quality. Uncertain energy prices in today‘s marketplace negatively affect predictable earnings, which are a concern, particularly for the publicly traded companies in the corn wet milling industry. For public and private companies alike, increasing energy prices are driving up costs and decreasing their value added. Successful, cost-effective investment into energy efficiency technologies and practices meets the challenge of maintaining the output of a high quality product despite reduced production costs. This is especially important, as energy-efficient technologies often include —additional“ benefits, such as increasing the productivity of the company.
Energy efficiency is an important component of a company‘s environmental strategy. End-of-pipe solutions can be expensive and inefficient while energy efficiency can be an inexpensive opportunity to reduce criteria and other pollutant emissions. Energy efficiency can be an efficient and effective strategy to work towards the so-called —triple bottom line“ that focuses on the social, economic, and environmental aspects of a business1. In short, energy efficiency investment is sound business strategy in today's manufacturing environment.
Voluntary government programs aim to assist industry to improve competitiveness through increased energy efficiency and reduced environmental impact. ENERGY STAR, a voluntary program managed by the U.S. Environmental Protection Agency (EPA), stresses the need for strong and strategic corporate energy management programs. ENERGY STAR provides energy management tools and strategies for successful corporate energy management programs. The current report describes research conducted to support ENERGY STAR and its work with the corn wet milling industry. This research provides information on potential energy efficiency opportunities for corn wet milling. ENERGY STAR can be contacted through www.energystar.gov for additional energy management tools that facilitate stronger energy management practices in U.S. industry.
In the following report, energy efficiency opportunities in the corn wet milling industry2 have been assessed. Almost $25 billion value is created from corn crop production. Wet milling uses 15% of that corn to make starch, ethanol, sweeteners, feed products, vegetable oil and other byproducts.3 Within the food and kindred products group (SIC 20), corn wet milling is the most energy intensive industry, using 15% of the total energy in the food industry (EIA, 2001). In addition, energy costs are the largest operating cost in corn wet milling and a large percentage of the total costs in corn wet milling (Hohmann and Rendleman, 1993). For a typical plant processing 100,000 bushels per day, approximately $15 to $25 million per year are spent on energy, whereas $250 to $300 million are spent on capital costs (Singh, 2002a). In this report, ways are presented to decrease these costs and increase energy efficiency.
This report begins with a description of the trends, structure and production of the industry in the U.S. The main production processes and the energy use in corn wet milling plants along with its end-uses are then summarized. In the remainder of the report is an examination of energy efficiency opportunities in corn wet milling plants. Measures and technologies that have successfully been demonstrated in individual plants in the U.S. or abroad, but that may still be implemented in other U.S. plants, are presented. Although new technologies are developed continuously (see e.g. Martin et al., 2000a), The
1 The concept of the —triple bottom line“ was introduced by the World Business Council on Sustainable Development (WBCSD). The three aspects of the —triple bottom line“ are interconnected as society depends on the economy and the economy depends on the global ecosystem, whose health represents the ultimate bottom line. 2 See Chapter 2 for a discussion of the classification of the corn wet milling industry that is used in this report. 3 Based on 2001/02 marketing year (USDA, 2002)
report is focused on practices that are proven and currently commercially available. Some of the technologies that may hold promise for the future but are still in the research and development phase are included in Section 5.8.
This report aims to serve as a guide for energy managers and decision-makers to help them develop efficient and effective corporate and plant energy management programs through information on new or improved energy-efficient technologies.
The Corn Wet Milling Industry
Corn wet milling is a relatively sophisticated process producing a variety of products for the paper, food, beverage and other industries. Table 1 gives an overview of the output from corn wet milling industries on a physical output basis and value basis for the last year information is available.4 Corn wet milling plants require a large capital investment and are bound by large economies of scale. Most plants in the U.S. process at least 100,000 bushels per day (bu/day, or 2,800 ton/day) and operate continuously for nearly 365 days per year, although approximately one quarter (ten) of the plants are smaller and have capacities less than 100,000 bu/day5. Capacities for U.S. plants are estimated in Appendix A.
Two major outputs of corn wet milling are corn sweeteners and ethanol. Both corn sweeteners and ethanol are made from the starch in the corn. Sweeteners fall into three major categories: corn syrup or glucose syrup, dextrose and high fructose corn syrup. Ethanol is an increasingly important component of the U.S. fuel supply. About 60% of the ethanol produced in the U.S. currently comes from corn wet milling6, generally produced in the refining factories along with starches and syrups. Corn starch is another important corn refining product, with both food and industrial applications, such as the paper and corrugating industries. Corn oil, produced from the germ component, is the other main high value product. Corn refining also produces many byproducts that are used in animal feed. Appendix B lists products by each corn wet milling company, along with a listing of their plant locations and company headquarters.
Corn refining has been the fastest growing market for U.S. agriculture over the past twenty years (CRA, 2002). Refiners currently use about 15% of the $25 billion corn crop (USDA, 2002). Some other grains are wet-milled in the U.S. today, but corn far exceeds the combined total of all of them (Matz, 1991).