Integrated Forest Biorefineries

By Lew Christopher

The Royal Society of Chemistry

Copyright © 2013 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-1-84973-321-2

Contents

List of Abbreviations, xxi,
Chapter 1 Introduction, 1,
Chapter 2 Vegetable Oil as a Fuel: Can it be used Directly?, 5,
Chapter 3 Biodiesel Properties and Specifications, 31,
Chapter 4 Oxidation Stability of Biodiesel, 51,
Chapter 5 Low-Temperature Flow Properties of Biodiesel, 80,
Chapter 6 Dependence of Other Properties of Biodiesel on Fatty Acid Methyl Ester Composition and Other Factors, 107,
Chapter 7 Major Resources for Biodiesel Production, 168,
Chapter 8 Diesel Engine Efficiency and Emissions using Biodiesel and its Blends, 140,
Chapter 9 Present State and Policies of the Biodiesel Industry, 204,
Chapter 10 The Food Versus Fuel Issue: Possible Solutions, 231,
Subject Index, 239,

CHAPTER 1

Integrated Forest Biorefineries: Current State and Development Potential

LEW P. CHRISTOPHER

Center for Bioprocessing Research and Development and Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City 57701, South Dakota, USA

Email: lew.christopher@sdsmt.edu; Tel.: + 1-605-394-3385

1.1 Introduction

The motivation for development and use of biofuels is currently driven by several important factors: 1) diminishing reserves of readily recoverable oil; 2) increasing demand and prices of petroleum-derived fuel; 3) concerns over increasing greenhouse gas emissions and global climate change; 4) growing food needs; and 5) desire for energy independence and security. The total energy world consumption in 2005 was 488 EJ with U.S. consumption of 22% of the world total, which is expected to surpass 650 EJ by 2025 and grow approximately 40% over the next 25 years. Future oil supply is not unlimited or assured as currently available petroleum fuel reserves are estimated to become nearly depleted within 40 years. Crude oil prices have risen from less than $20/ barrel in the 1990s to nearly $100/barrel in 2007 with a current annual volatility of crude oil prices exceeding 30%. Government-controlled national oil companies and organizations, many in countries that are unstable or prone to conflict, command and control more than 75% of the world’s known oil reserves and global oil production. The U.S. imports 10 million barrels of oil per day of the existing oil reserves of 1.3 trillion barrels.

In 2004, fossil fuels accounted for 86% of the U.S. total energy consumption, with an additional 8% from nuclear power and only 6% from renewable sources, including 3% of biomass-derived biofuels. Biomass, however, is the single renewable resource on earth, reproduced at 60 billion tons per year (as organically-bound carbon), that has the potential to supplant the use of liquid transportation fuels and help create a more stable energy future. In general, around 30% of the world’s primary energy is derived from biomass with around 430 g carbon produced per square meter of land per year. The U.S. and other regions of the world have abundant biomass resources which are much more evenly distributed and accessible throughout the planet than the oil reserves. In their “billion ton vision”, the U.S. Department of Energy (DOE) reported that nearly 1.3 billion dry tons of biomass could become available to produce biofuels and displace more than 30% of the nation’s consumption of liquid transportation fuels. However, the biomass share of the U.S. energy supply in 2004 was less than 3% of the total, compared to 40% and 23%, derived from petroleum and coal, respectively. Although biomass ranks well below petroleum, natural gas, and coal and is about one-half of nuclear, it surpasses hydroelectric and other renewable sources, and in 2009, the share of biomass in the total U.S. energy consumption exceeded 4% for the first time.

While ethanol production from corn and sugarcane (first generation biofuels) is a well-established process, cellulosic ethanol (second generation biofuels) is yet to be commercialized. The DOE Roadmap envisages large-scale production of second generation biofuels to become a nation-wide reality beyond 2020. The cellulosic biomass base is composed of a wide variety of forestry and agricultural resources that include forest thinning, wood mill residues, logging residues, paper waste, tree trimmings, grass clippings, energy crops such as switchgrass and miscanthus, sugarcane waste (bagasse), wheat straw, rice straw, corn stover and corn cobs.

According to the “billion ton vision” of DOE, two-thirds of the biomass resources in the U.S. represent agricultural waste, whereas about a third is forest-based. Forests cover 30% of the earth (about 3.9 billion hectares) and play a major role in preservation of biodiversity, soil conservation, and prevention of climate change serving as a major carbon dioxide sink. The forest resources are sustainable and provide long-term economic benefits to more than 1.6 billion people with a market of forest products estimated at $327 billion per year. Wood is used to produce heat for domestic and industrial purposes, and due to its strength properties, it is the primary construction material in more than 145 countries around the world. Wood is also used as a chemical feedstock to produce charcoal, tar, pitch, pulp fibers, paper, etc. Therefore, the wood-based value chain includes wood products, paper products, energy, and wood-derived chemicals. Due to the wood’s increasing use and demand, approximately 130 000 km2 of forest are lost as deforestation every year. In addition, large areas of forest lands are littered with an unnatural accumulation of stunted, overcrowded trees and woody debris. Decades of fire suppression have disrupted the natural fire cycle of U.S. forests. Fires on these overstocked stands are more intense and harder to control than forest fires in previous decades, and they often result in catastrophic crown fires that kill large areas of forestlands. An estimated 8.4 billion dry tons of material needs to be removed from the national forests to reduce the risk of fire hazard, insect infestation, and disease. This vast source of biomass is available for production of wood products, chemicals, and energy. The biomass-derived energy use is projected to grow 35% from 2010 to 2024.

To combat the above processes, sustainable forest management practices need to include activities such as forest carbon credits, afforestation, reforestation, and the active support of government, forest companies and landowners. Government policies, carbon credits and carbon markets can be used as a tool to offset greenhouse gas (GHG) emissions. “Carbon credit” is a generic term for any tradable certificate or permit representing the right to emit one ton of carbon dioxide or the mass of another greenhouse gas with a carbon dioxide equivalent to one ton of carbon dioxide. Since GHG mitigation projects generate credits, this approach can be used to finance carbon reduction schemes between trading partners and around the world though carbon markets. Plant-derived biofuels as a carbon-neutral technology have to achieve at least 60% lower emissions than petroleum fuel based on lifecycle studies that include all emissions resulting from making the fuel from the field to the tank. Meeting these goals will require significant and rapid advances in biomass feedstock and conversion technologies; availability of large volumes of sustainable biomass feedstock; demonstration and deployment of large scale, integrated biofuels production facilities; and development of an adequate biofuels infrastructure.

The use of non-food cellulosic biomass to produce biofuels presents a solution to the growing food vs. fuel debate – the dilemma regarding the risk of diverting farmland or crops for biofuels production in detriment of the food supply on a global scale, thereby having potential adverse impacts on food price, land use change, carbon and energy balance. For example, the share of corn destined to ethanol production in the U.S. reached 25% in 2007 and according to a recent study for the International Centre for Trade and Sustainable Development, the market-driven expansion of ethanol in the U.S. increased corn prices by 21% in 2009, in comparison with what prices would have been, had ethanol production been frozen at the 2004 level. However, the United Nation’s Organization for Economic Cooperation and Development (OECD) released a report in 2008 that provided estimates according to which up to 12% of the global coarse grain production and 14% of global vegetable oil production could be used for biofuels without having any significant impact on food prices.

The Energy Independence and Security Act (EISA) of 2007 established a lifecycle GHG standard of 20% emission reduction for corn-based ethanol, based on the 2005 emission level, which would discourage the use of coal for process heat and limit further expansion of corn-based ethanol plants. The life-cycle analysis (LCA) studies mandated by EISA, dealing with data quality, allocation, system boundaries and sensitivity analysis, can profoundly shape the conclusions of biofuels production and land use change analysis. Using GHG and energy as functional units, the biofuel LCA accounts for the inputs and outputs of biofuel production, characterized in terms of energy requirements and yields, economic costs and benefits, and environmental costs and values. Most LCA results for lignocellulosic crops conclude that biofuels can supplement energy demands and mitigate GHG emissions to the atmosphere because fermentation-derived ethanol is already part of the global carbon cycle. Also, blending oxygenates such as ethanol and methyl tertiary butyl ether (MTBE) are well recognized for causing reduced carbon monoxide levels by improving the overall combustion of the fuel. However, global equilibrium economic models have estimated that indirect land-use change associated with an increased use of corn-based ethanol could potentially double GHG emissions associated with that fuel pathway in the next 30 years. This model is based on projections which suggest that biofuels would cause farmers to convert forests and grasslands to new agricultural lands that would otherwise be conserved. Measuring what really changes as a result of bioenergy policies and crops compared to what is expected to occur in their absence is an important challenge that must be addressed to improve land-use accounting. To protect ecosystems and improve livelihoods through more sustainable land-use practices, the forces that actually drive deforestation should be better understood. From this perspective, pro- vided environmental preservation concerns are met, deforestation could be minimized, if much underutilized land is used for biomass production.

EISA contains a number of provisions to increase energy efficiency and the availability and use of renewable energy in the U.S. One key provision of EISA is the setting of a revised Renewable Fuels Standard (RFS). The revised RFS mandates the use of 36 billion gallons per year (BGY) of renewable fuels by 2022. The revised RFS has specific fuel allocations for 2022 that include use of: 16 BGY of cellulosic biofuels; 4 BGY of advanced biofuels; 1 BGY of biomass-based biodiesel; and 15 BGY of conventional biofuels (e.g., corn starch-based ethanol). This potential resource is more than sufficient to provide feedstock to produce the required 20 BGY of cellulosic biofuels by 2022 – the year in which the revised RFS mandates the use of 36 BGY of renewable fuels. By 2030 the target is to replace 30% of the transportation fuel supply with biofuels, equal to 60 billion gallons of ethanol, which would require the use of approximately 0.75 billion tons of biomass.

In 2009, the U.S. produced 10.94 billion gallons of ethanol, and together with Brazil, both countries accounted for nearly 90% of the world’s production. In 2010, the ethanol production in the U.S. reached 13.30 billion gallons which exceeded the RFS mandate for the previous year – 2010, whereas in 2011, 13.95 billion gallons of ethanol were produced. In U.S. alone, the number of ethanol biorefineries increased from 110 (as of January 2007) to 209 (as of January 2012). For the same period, the ethanol production capacity increased by more than 60% – from 5.5 BGY to 14.9 BGY (http://www.ethanolrfa.org/pages/statistics/). The recent increase in ethanol production was driven by a combination of high crude oil prices, RFS for domestic renewable fuel consumption, tax credits for ethanol blenders, and large net exports in 2010 and 2011.

However, ethanol production in the U.S. is still mainly corn-based, therefore, breakthrough technologies are needed to make cellulosic ethanol cost-competitive with corn-based ethanol. Although significant progress has been recently made towards commercialization of cellulosic ethanol, there are still economic, social and environmental challenges that need to be addressed. These include significant and rapid advances in biomass feedstock and conversion technologies; availability of large volumes of sustainable biomass feedstock; demonstration and deployment of large scale, integrated biofuels production facilities; and development of an adequate biofuels infrastructure. A minimum profitable ethanol selling price of $2.50/gallon can compete on an energy-adjusted basis with gasoline derived from oil costing $75–$80/barrel. At the lower oil prices ($45–$50/barrel), cellulosic technology may not be as competitive and could require policy supports and regulatory mandates to drive the market. The biofuels and bioproducts strategies need to be based on a thorough assessment of opportunities and costs associated with the upward pressure on food prices, intensified competition for land and water, and deforestation. As the feedstock costs comprise more than 20% of the production costs, it has now been widely recognized that biomass waste such as agricultural and forest waste can provide a cost-effective alternative to improve the economic viability of bioethanol production. Despite technology advancements and declining processing costs for biofuels production, the profit margins for ethanol plants have been shrinking due to increasing feedstock costs and soaring prices of agricultural commodities. Costs and subsidies for biofuels are partly compensated by the expected economic, environmental and social benefits including increased energy security and reduced dependence on imported fossil-based fuels; diversification of energy and chemicals supply and markets; reduction of GHG emissions to mitigate climate change; job creation opportunities in rural areas; and overall improvement of quality of human health and life.

The supply and demand forces of market fundamentals have contributed to volatility in oil prices in recent years, and by transitioning toward higher energy efficiency and additional domestic sources of renewable fuels, such as biofuels, there is high potential to reduce U.S. market uncertainty and increase energy security. The depleting oil reserves and the use of traditional fuel with the associated logistics issues can be offset by deploying biorefineries that integrate various conversion technologies to derive energy and chemicals from locally available biomass resources. Furthermore, co-products such as corn gluten feed and meal, corn oil, glycerin, natural plastics, fibers, cosmetics, liquid detergents and other bioproducts, will increase with biofuel production and improve profitability. Currently, however, of the 100 million metric tons of chemicals produced annually in the U.S., only about 10% are biobased.

1.2 Integrated Forest Biorefineries

A biorefinery is a facility that integrates biomass conversion processes and equipment for sustainable processing of biomass into a spectrum of value-added bio-based products (food, feed, chemicals, materials) and bioenergy (biofuels, power and/or heat). The biorefinery is analogous to today’s petroleum refinery, which generates multiple fuels and products from petroleum. However, in contrast to the petroleum-based products, the biorefinery products are non-toxic, biodegradable, reusable and recyclable. The biorefinery takes advantage of the various components in biomass and their intermediates, therefore maximizing the value derived from the biomass feedstock. It employs a multidisciplinary approach that integrates physical and mechanical methods, chemical and biological conversion, catalysis and biocatalysis to obtain high-efficiency, low-cost, and low-energy consumption. Biorefineries are continuously evolving as new advancements in research of biomass feedstock, related processes and products become available for sustainable energy production – a challenge and an opportunity that we currently face in our endeavors to transition to a biobased economy and society.

An Integrated Forest Biorefinery (IFBR) is a biorefinery that can process forest-based biomass such as wood and forestry residues to bioenergy and bioproducts including cellulosic fibers for pulp and paper production (Figure 1.1). As lignocellulose consists of four major components – cellulose, hemicellulose, lignin and extractives (Table 1.1) – the IFBR has four production platforms that can be used in an integrated manner for production of biofuels and high-value bioproducts. A unique feature of the IFBR is that the cellulose platform is predominantly dedicated to production of pulp and paper rather than cellulosic ethanol. The existing prototype of the future IFBR are the pulp and paper mills, in particular the chemical pulp mills. The pulp and paper industry has the world’s largest non-food biomass collection system that pro- vides a primary source of cellulosic feedstocks. The U.S. paper and forest products industry made a commitment to increase the development of biomass fuels with the strategic goal of evolving existing pulp and paper mills into forest biorefineries that export substantial amounts of renewable, sustainable energy and chemical products while continuing to meet the growing demand for traditional pulp, paper and wood products. The pulp and paper mills are most suited for biorefinery large-scale developments as they are located near the forest and agricultural residuals and have existing infrastructure to transport the raw materials and finished products. In the U.S. alone, mills collect and utilize over 120 million dry tons of wood per year as a raw material and pro- duce power from biomass of which nearly 60% is derived from wood residuals and spent liquors. Furthermore, pulp and paper mills also have a highly trained workforce capable of operating energy and biorefinery systems. The U.S. pulp and paper industry is the world’s largest manufacturer of forest products that employs nearly 1.3 million people with a payroll of over $50 billion per year. In 2010, the U.S. produced 76 million tons of paper and paperboard and nearly 50 million tons of wood pulp. However, the U.S. pulp and paper and other fiber processing industries need to create additional revenues and diversify their products and markets to remain competitive. This would enhance the profitability of these facilities thereby providing a higher degree of technological and market flexibility and economic independence. There are a number of reasons that necessitate the conversion of pulp and paper mills into IFBRs: 1) unstable, fluctuating oil prices and uncertainties about oil reserves; 2) strong, increasing off-shore competition; 3) global warming and increasing GHG emissions; 4) global movement toward and incentives for green fuels and chemicals.

(Continues…)Excerpted from Integrated Forest Biorefineries by Lew Christopher. Copyright © 2013 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.