Decision-Making for Biomass-Based Production Chains

The Basic Concepts and Methodologies

Sebnem Yilmaz Balaman

• Publisher: Academic Press
• Year: 2018
• ISBN:
  9780128142790
• Topic: Physical Sciences
• Subtopic: Energy

Decision-Making for Biomass-Based Production Chains: The Basic Concepts and Medothologies presents a comprehensive study of key-issues surrounding the integration of strategic, tactical and operational decision levels for supply chains in the biomass, biofuels and biorefining sectors. Comprehensive sections cover biomass resources, harvesting, collection, storage and distribution systems, along with the necessary technical and technological background of production systems. In addition, the basics of decision-making, problems and decision levels encountered in design, management and operation phases are covered. Case studies are supplied in each chapter, along with a discussion and comparative analysis of topics.

The book presents a clear vision of advances in the field. Graduate students and those starting in this line of research will also find the necessary information on how to model this kind of complex system. Finally, this comprehensive resource can be used as a guide for non-expert industry decision-makers and government policymakers who need a thorough overview on the industry.

• Examines analytic methodologies for complex decision-making when designing, deploying and managing biomass and bio-based products supply chains
• Includes real-life examples of main sustainability indicators, standards and certification schemes from the European Union, United States and worldwide
• Explores the progress of decision-making procedures to provide a detailed perspective for effective selection of the most reliable solutions for each kind of problem
• Provides detailed, in-depth analyses of various models and frameworks for their implementation, challenges and solutions
• Presents multi-criteria and multi-objective decision-making and modeling approaches, including mathematical modeling, simulation-based modeling, and artificial intelligence-based modeling

Chapter 1

Introduction to Biomass—Resources, Production, Harvesting, Collection, and Storage

Abstract

The main aim of this chapter is to show that a comprehensive understanding and perspective, on the basics of biomass sources, is required to develop efficient modeling and solution frameworks and solve the real-world problems effectively by selecting the most appropriate methodologies considering the characteristics of available biomass sources. To this aim, this chapter presents a comprehensive introduction to the biomass concept, covering the main biomass resources utilized commonly throughout the world under three categories of biomass, energy crops, residues, and wastes, as well as production, harvesting, collection, handling, pretreatment, and storage processes for all overviewed biomass resources. Information is also given on recent trends in biomass production that offer new biomass alternatives. Eventually, a discussion and a comparative analysis of the topics covered in the chapter are provided to reveal the impacts of different types of biomass resources, as well as biomass production and other related activities, on methodology selection, and application for decision-making in biomass-based production problems.

Keywords

Biomass sources; energy crops; residues; wastes

Chapter Outline

• 1.1 Biomass Concept and the Main Biomass Resources 1
  • 1.1.1 Dedicated Energy Crops 2
  • 1.1.2 Residues 8
  • 1.1.3 Wastes 13
• 1.2 Recent Trends in Biomass Production 19
• 1.3 Discussion 20
• References 22
• Further Reading 23

1.1 Biomass Concept and the Main Biomass Resources

Biomass is a biological material derived from living, or recently living organisms available on a renewable basis, which contains complex mix of carbon, nitrogen, hydrogen, and oxygen. Biomass resources, sometimes referred to as bio-renewable resources, are all forms of organic materials, including plant matter both living and in waste form, as well as animal matter and their waste products. Various biomass resources are converted into bio-products by different conversion processes in biomass-based production chains throughout the world. But the key to utilizing biomass resources in a beneficial way is to focus on the most appropriate resources, considering the characteristics of the conversion and handling systems, and use them at an appropriate scale. A good understanding on biomass resources as well as their production, collection, handling, pretreatmenttreatment, and storage is critical for efficient design and management of biomass-based production chains. This chapter presents a comprehensive overview on biomass resources, as well as production, harvesting, collection, handling, pretreatmenttreatment, and storage processes, for all overviewed biomass resources under three categories of biomass, energy crops, residues, and wastes. Fig. 1.1 depicts the biomass resources focused in this chapter.

Figure 1.1 The classification of biomass resources covered in this chapter.

1.1.1 Dedicated Energy Crops

Until the first oil crisis of the 1970s, when a sudden rise in the price of oil led to the first push for the development of renewable energy production, energy crops have been largely ignored in favor of growing food crops to feed people and animals. After this period, many governments supported the development of novel nonfood crops for energy production in addition to food production. Interest in crop production for energy purposes is now increasing as the economics of extracting fossil fuel-based energy becomes more expensive and there is an increasing concern over energy security. In addition to volatile and increasing oil prices, numerous reports draw attention to the substantial cost to humankind of not acting to reduce the current rate of increase in greenhouse gas emissions. As the use of fossil fuels significantly contributes to climate change, the need for alternative energy sources to save carbon is placed at the top of the global agenda. However, the global population continues to grow at an alarming rate, and people both need to be fed and are consuming more energy. This raises trade-offs and questions of “Food versus Fuel,” how much land and other resources are available, what are the priorities, and how should they be divided between food and fuel production? Over the years, the large-scale production of energy crops has become a highly controversial topic, in that each crop must compete for arable farmland for food purposes, and as to whether or not it is sustainable or viable to use such large areas of farmland and forests, to produce dedicated energy crops, has been the subject of much debate. These questions should be answered and trade-offs should be considered while designing and managing biomass-based production systems and supply chains, especially in planning the land-use for energy crop production.

Dedicated energy crops are defined as nonfood energy crops that are unsuitable for human or animal consumption, and are grown primarily for the purpose of producing biomass, to be converted into energy and/or fuel on marginal land dedicated to provide biomass. Dedicated energy crops can be investigated in two general categories; herbaceous energy crops and woody energy crops.

1.1.1.1 Herbaceous Energy Crops

Herbaceous energy crops, also referred to as grassy or forage energy crops, are high-yielding lignocellulosic crops that remain in cultivation for several seasons and are harvested, on average once a year, after taking two to three years to reach full productivity. Energy crops within this definition are perennial in nature, so that they can be cut and harvested for biomass over successive years without recultivation or sowing, and the whole crop can be harvested and used for energy production.

They have several advantages over other types of energy crops, such as, they have efficient solar energy conversion resulting in high yields, need low agrochemical inputs, have a low nutrient and water requirement due to their extensive rooting system, which holds onto fertilizers and water, have low moisture levels at harvest, and plants with perennial growth habits also have the benefits of low establishment costs and fewer annual operations (Fernando et al., 2017; Adams and Lindegaard, 2016). These include grasses such as switchgrass, miscanthus (also known as elephant grass or e-grass), bamboo, sweet sorghum, wheatgrass, tall fescue, kochia, etc. Among them, switchgrass and miscanthus are the most commonly used biomass resources because they are adaptable to many climatic zones, require relatively low water and nutrients, are adaptable to low-quality land, and have a minimum of 10 years productive life (10 years for mischantus, 10–20 years for switchgrass) (Allen et al., 2014). Also, they have positive environmental impacts because of their deep roots and ground cover, so that the cultivation of them in marginal soils has the potential to restore soil properties (fertility, structure, organic matter) and reduce erosion (Stewart et al., 2015).

1.1.1.2 Woody Energy Crops

Woody energy crops (also referred as short-rotation woody crops), mainly consist of fast-growing hardwood tree species that are harvested within five to eight years of planting. These include poplar, willow, eucalyptus, silver maple, eastern cottonwood, green ash, black walnut, sweetgum, and sycamore. Among them, poplar and willow are also referred as Short-Rotation Coppice.

Woody energy crops feature high biomass productivity, that is, higher than long-rotation forest systems grown on forest land (Hauk et al., 2017). They also require a low level of input when compared with annual crops. In addition, the production of woody energy crops requires few working steps and little to no pesticide and fertilizer; hence the production of biomass is energy efficient (Don et al., 2012). They also have positive external effects, such as reduced soil erosion and increased soil quality. Despite these benefits, they are not widespread in North America and many European states, such as in southern Germany, due to long investment periods and perceived economic disadvantages (low profitability and high risk) (Don et al., 2012).

Short-rotation woody crops can be specified as purpose-grown trees that are planted as purpose-grown wood on sites that enable high productivity and proximity to the processing plant. These purpose-grown trees offer a variety of inherent logistical benefits and economic advantages, compared with other lignocellulosic energy crops, because of their ability to provide a stable supply of feedstock and relatively lower collection and handling costs (Hinchee et al., 2009). The fact that trees provide a renewable inventory of available biomass through year-round harvest and a continuity of growing, year by year, results in a flexibility in harvest time that leads to advantages, such as minimized inventory holding costs, reduced degradation losses associated with storage of annually harvested biomass, as well as production, distribution, and storage throughout the year ensuring full capacity utilization at a processing plant. In addition, the flexibility that trees can be harvested at different times aids in accommodating annual fluctuations in biomass supply due to natural reasons (e.g., disease, pest, or drought).

1.1.1.3 Plantation and Harvesting of Dedicated Energy Crops

1.1.1.3.1 Site Selection and Preplanting Site Preparation

Since herbaceous energy crops are perennial, and that they will exist on the dedicated plantation site for at least 15–20 years, site selection is an important phase of designing supply chains for the production of herbaceous energy crops. These crops can reach up to 3.5 m in height, hence their impact on the local landscape, particularly if the site is close to a footpath or an adjacent landowner, needs to be considered when selecting the plantation site.

Currently, the leading countries in areas planted for energy generation from Short Rotation Coppice (SRC) are Sweden and the United Kingdom (Mola-Yudego and González-Olabarria, 2010). SRC can be planted on a wide range of soil types from heavy clay to sand, including land reclaimed from gravel extraction and colliery spoil (DEFRA, 2007). As SRC requires more water for its growth in comparison with any other conventional agricultural crop, the plantation site should have a good moisture-retentive soil. The area of the site should be adequate (large and regular shaped) for large harvesting machinery is involved. At the end of a three-year growing period, the SRC will be up to 8 m tall, hence creating a three-dimensional mass in the landscape. For this reason, it is important to design and construct SRC plantations to prevent adverse views on the landscape.

It is essential to establish the plantation site correctly and effectively, to avoid possible future problems, since the crop has the potential to be in the ground for at least 15 years. For effective establishment and crop management to guarantee high yields, thorough site preparation is essential.

As the first step in the site preparation for herbaceous energy crop plantation, the site is sprayed with a suitable herbicide, to control perennial weeds in the autumn before planting and the site should be cultivated immediately before planting in the following spring. Therefore, soil aeration will be improved and root development will be supported to enhance the establishment (Planting and Growing Miscanthus, Best Practice Guidelines, 2007). For the case of SRC plantation site preparation, at least 10 days before plowing the SRC plantation site, herbicide application is required.

1.1.1.3.2 Planting and Harvesting

Herbaceous energy crops are established from seed, which is generally available from commercial suppliers. First-year growth is insufficient to be economically worth harvesting, hence, after planting, a minimum of two to three years is required to achieve maximum annual yields. Weed control is important during the first year (Wolf and Fiske, 1995). Although irrigation is necessary to grow switchgrass and other warm-season plants, permanent irrigation may not be cost-effective for herbaceous energy crop systems. The deep and extensive root system of herbaceous energy crops enables them to sustain good growth even in periods of infrequent rainfall. Despite this fact, Ocumpaugh et al. (2003) stated that a watering interval of seven days or less was critical to obtaining seedling survival of 90% or more in all soils.

Underground storage organs (also known as rhizomes) of Miscanthus, of which pieces can be replanted to produce new plants, naturally provide slow spreading. Miscanthus is quite an adaptable energy crop by means of its roots that can extract water to a depth of around 2 m, and it grows on a range of soils, from sand to high organic matter soil. However, the yields are strongly influenced by annual rainfall frequency and soil water retention at any site. To obtain a high yield of herbaceous energy crops, key determinants are sunshine, temperature, and water availability, of which annual variability results in annual yield variations. Also, any site-specific microclimatic conditions will affect the annual yield.

The key determinants that influence SRC yield are water availability, weed control, light, and temperature. The root system and stumps of SRC are well-established where the nutrients are able to be stored to guarantee vigorous growth for the shoots. The high moisture content of the soil in the spring and the adequate amount of sunshine in the summer make March an ideal planting time for SRC. The large initial investment cost of plantations may be intimidating since there is no financial payback for four years from the initial establishment. However, in the United Kingdom grants are available to support establishment and in Sweden an extensive scheme of subsidies was developed between 1991 and 1996, being reduced after that time (Mola-Yudego and González-Olabarria, 2010). Although SRC is a relatively low-return crop, it requires low-maintenance, and planting SRC is a way of utilizing difficult and idle fields with little need for pesticides or treatments.

Harvesting of herbaceous energy crops has usually been accomplished using conventional mowing, raking, and baling equipment on slopes of less than 35 degrees (Wright et al., 2011). The timing of the harvest depends on the primary aim of crop-use and may occur once or twice during the growing season, that is, twice if harvested for forage, once if harvested for bio-energy production. Harvesting can take place during the winter or from late February to early May, as long as weather conditions permit. However, delayed harvests may cause some loss of biomass. To obtain a dry and baled product, which is desirable for energy generation purposes, the crop is cut with a forage harvester, then baled with a number of different types of baler, each suitable for different scales of energy production facilities and producing bales in different shapes (e.g., rectangular, round, and compact rolls).

Harvesting of SRC takes place on a two- to five-year cycle, and are carried out in winter when the soil is frozen (usually from December to mid-March). There are four different types of harvesting SRC; direct-chip harvesting, harvesting as entire rods, harvesting into round bales, and harvesting into billets (Caslin et al., 2010). To store the SRC more easily, shoots are harvested as whole stems, which then can be dried until the next autumn when the moisture content of the wood will decrease to about 30% on average. Then, the dried stems can be either converted into wood chip or cut further into billets depending on use. In the cas...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1. Introduction to Biomass—Resources, Production, Harvesting, Collection, and Storage
• Chapter 2. Biomass-Based Production Systems
• Chapter 3. Biomass-Based Supply Chains and Logistics Networks
• Chapter 4. Sustainability Issues in Biomass-Based Production Chains
• Chapter 5. Uncertainty Issues in Biomass-Based Production Chains
• Chapter 6. Basics of Decision-Making in Design and Management of Biomass-Based Production Chains
• Chapter 7. Modeling and Optimization Approaches in Design and Management of Biomass-Based Production Chains
• Index