Sugar Cane Ethanol Plant

Executive Summary

As the alternative energy industry continues to grow in the United States, Global Impact Chemical Corporation (GICC) has taken interest in producing vehicle biofuel from plant matter such as sugarcane. With a capital cost limitation of 1 billion USD, a process plant design and the corresponding economic analysis were devised. Liberia, Guanacaste Province, Costa Rica was chosen as the plant’s location due to inexpensive cost and proximity to rich natural resources. Due to market demand of anhydrous ethanol in the United States and hydrous ethanol in Brazil, both forms of ethanol may be produced with the proposed plant design.

Research on current ethanol manufacturing processes guided the final design of the ethanol plant. The proposed design was divided among three major processes: milling, fermentation, and separations. An electricity cogeneration system and an additional bagasse hydrolysis process assist in keeping the proposed plant self-sufficient and increase ethanol production. Microsoft Visio and Aspen HYSYS were used to design complete process flow diagrams and simulate the fermentation and separations processes. All other calculations were performed in Microsoft Excel. It was estimated that an initial feed of 147 tons per hour of sugarcane, milled and fermented with the bacteria S. Cerevisiae, produced the desired total of 20,000 kg/h of hydrous ethanol and 19,500 kg/h of anhydrous ethanol. Aspen Economic Analyzer aided in estimating the cost of the sized equipment in each of the three major processing steps. The total capital cost of the plant, as designed, is estimated as $465.9 million.

Economic analysis predicts a net present value of $240 million on a twenty-year basis. Furthermore, the estimated rate of return is 19.7% after twenty years, with a pay-back period of 4.10 years, satisfying the desired payback time of three years. A gross margin percentage of 70% after plant startup was calculated, thus the plant’s potential financial performance is significantly better than the average range of 40-50%. According to the analysis, the proposed sugarcane ethanol plant design would be economically viable and would provide GICC with a promising first step towards a biofuel for alternative fuel vehicles.

Introduction

Fuel ethanol has been an important alternative fuel for decades. With petroleum prices reaching upwards of $100 per barrel on a regular basis, the market for fuel ethanol is poised to grow even further. Currently the largest producer of ethanol in the world is Brazil, where a combination of fuel composition standards, supplier incentives, and low sugarcane prices combine to make the production of sugarcane ethanol a lucrative opportunity. The market in Brazil appears to be nearing saturation, however, as evidenced by a growth rate in production of only 5% from 2009 to 2010 [1]. This pales in comparison to the near 30% growth that the US market has experienced over the last 5 years. It is believed that much of this growth is due to the high gasoline prices in the country and that this may be addressed by an increase in the production of alternative fuels. Our team has decided to pursue the design of a sugarcane ethanol plant to be located in Costa Rica which will serve both the domestic, Costa Rican market, and the US market. Costa Rica offers an area with low sugarcane prices which will allow us to follow the more efficient sugarcane-fed process instead of the cornbased process pursued in the US. Costa Rica also offers free-trade agreements [2] which allow the ethanol to pass into the US tariff free, providing a significant advantage over Brazilian competitors.

Anhydrous ethanol, contains 99.5 wt% ethanol, while hydrous ethanol contains only 95 wt% ethanol. Anhydrous is required for vehicle use in the United States, as opposed to Brazil which uses hydrous. The key difference is an azeotrope that is required to be crossed in the ethanol-water mixture to distill to anhydrous ethanol.

The actual design of our plant was driven by current manufacturing processes found in literature. The design is split up into four main sections for simplicity which are milling, fermentation, separations, and utilities. Aspen HYSYS was used to model the separations process unit while Microsoft Excel was used in the design of the fermentation and milling units. All Process Flow Diagrams were produced in Microsoft Visio.