September 19, 2014

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Total Liquefaction of Biomass

Title: Total Liquefaction of Biomass
PI(s) : Roger Ruan, and Paul Chen (2001)
Dept :  Biosystems and Agricultural Engineering
Funding Source : US Army Natick Research Center, AURI

Summary

OVERALL GOAL AND APPROACHES
The overall goal of this proposed project is to turn sugar cane industry into an energy self-sufficient industry that produces not only sugars but also feed, chemicals, materials, and energy. This project falls into the specific grant uses (1)A,C, (2)D, (3)B, C and (4) defined in the RFP.
The approaches to reach the goal are:

  • Improving sugar cane production (traditional vs. energy cane, better suited for biobased industry, genetic alteration to improve yield and non-sugar quality);
  • Improving manufacture of traditional products (sugars, or NCS, feeds);
  • Developing energy production technologies (gasification, fermentation-ethanol, direct combustion);
  • Developing technologies for production of chemicals and materials from fibrous sugar cane residues, wastes/byproducts generated during sugar production (extraction, fermentation, liquefaction); and
  • Comprehensive study of agronomics, economic, and bio-energy balance

OUTCOME AND BENEFITS
The outcome of this project will shape sugar cane into an energy crop, and create a new economic platform for the nation’s sugarcane industries, which will support sustainable Hawaiian agriculture. Specifically, the research are expected to result in an improved biomass (sugar cane) production, harvest, handling and recovery system, and an energy self-sufficient biorefinery that produce not only sugars, but also energy, feed, chemicals, and materials.

An economy based on renewable resources such as biomass will certainly supplement energy and material production from fossil resources, and offer strong possibility of displacing the use of petroleum, while having positive impacts on the environment and rural economies. Perhaps most importantly to US farming industry, producing energy, chemicals and materials from renewable biomass resources means new markets for agriculture. Opening new uses for agricultural crops can reduce the effect of food commodity market limits on agricultural product prices, and deliver higher returns to farmers.

Description

INTRODUCTION
ENERGY, ECONOMY, AND ENVIRONMENT RELEVANCE
Sugarcane is among the plant kingdom’s most efficient converter of sunlight into chemical energy stored in sugars and fiber. In Hawaii, sugarcane can produce in excess of 150 tons fresh weight of biomass per acre and industry-wide, it averages around 100 tons per acre. Traditionally, the main products of sugarcane are sugar, molasses, and fiber for fuel. These three yield products are obtained from the harvested (millable) cane while the tops and trash are removed by burning the crop in the field prior to harvest. Evolving technologies for the conversion of each of these fractions into higher value bio-based industrial products, including energy, is rapidly expanding the potential for this crop to meet a part of the nations needs to offset dependence on petroleum and to improve energy security, balance of payments, environment, and rural economy.

The sugarcane industry in Hawaii is one of the top biopower producers in the nation[1] and has the capability to increase its role by implementing its long-term strategy to eliminate its long standing practice of preharvest burns. Industry estimates indicate the burnt leaves represent approximately 30% of the available total fiber.[2] This represents a significant underutilized feedstock for biobased product development. Environmental concerns emphasize the need to identify an alternative use for this resource while global competition in the global market indicate the need for the industry to reconfigure its’ revenue profile for long term economic viability.

If this integrated solution is proven successful, a similar system can be adopted in Southern United States where sugarcane or other high productivity energy grasses can be grown. Midwest agriculture generates a tremendous amount of biomass that can also be utilized to produce biopolymers. Among them are corn stover, beet pulp, soybean, and sunflower hulls, along with wheat and forest waste.

In all cases, although some residue is beneficial to protect the soil from erosion, most residues can be safely taken out of the fields for valuable utilization, which has the potential to be a win-win situation for the producer, processor, and the environment. The farmer wins from the product sales, reduced cultivation costs and possible carbon credits for the greenhouse gas offset. The processors make value-added industrial products which are previously produced from petroleum. The environment benefits from improved agricultural practices and fewer green gas emissions.

TECHNICAL RELEVANCE
Energy Cane Concept
The biomass produced by sugarcane might have high sugar and low fiber contents as in commercial varieties, or it might be low in sugar and high in fiber as in wild relatives of sugarcane. Since both sugar and fiber can be converted in a processing factory into industrial raw materials (Figure 1), a wide range of products can be produced from this crop. In addition, biotechnology is now making it possible to modify the genetics of the sugarcane plant so that the raw material input is different so that totally unique products might be manufactured directly in the green plant, improving the plant as a biofactory.

Energy Self-Sufficiency
Biomass not only provides food, feed, fiber, and a wide range of necessary products like shelter, packaging, clothing, and communications, but also is a source of a large variety of chemicals, materials, fuels, and energy. The processes for producing sugars, feeds, chemicals, materials, etc., could be improved and developed to the point of energy self-sufficiency of sugar cane industry. For example, steam from burning bagasse can be used to generate electricity for plant operations, or directly provide heating for biomass conversion processes such as fermentation and liquefaction. A precommercial biomass gasification research facility on Maui successfully demonstrated the technical feasibility of producing fuel gas (biogas) from sugar cane bagasse. The biogas could be utilized in gas turbines for generating electricity and for producing methanol fuel for transportation purposes. Study is necessary to develop an integrated technical plan for energy conversion for sugar cane industry.

Biorefinery Concept
For more than a century, petroleum refinery has been a most important part of the world economy. Many usable commodities are derived from an adjustable conversion of petroleum. New technologies, new laws, and increasingly environmentally aware public are ushering in a new materials base for the 21st century. It is called “carbohydrate economy”. Many polymeric materials conventionally derived from petrochemicals can also be produced from renewable resources such as biomass. The market potential for bio-based products is very promising. The “2003 Roadmap for Biomass Technologies in the United States” forecasts a large increase in bio-based products. Production of chemicals and materials from biomass will increase substantially from approximately 12.5 billion pounds, or 5 percent of the current production of target U.S. chemical commodities in 2001, to 12 percent in 2010, 18 percent in 2020 and 25 percent in 2030.

Sugar cane is a perfect feedstock for biorefining. Sugars and molasses are very easy to convert. However, technology is needed for efficient conversion of fibrous portion of the crop. Many technically feasible approaches are available to convert biomass to biopolymers. However, no large-scale commercial facility is operating to date. This situation can be attributed to a combination of the following three factors, technical inadequacy, economical non-competitiveness, and lack of understanding of the industrial need.