**3.1. A value chain model for bioenergy production**

electricity generation [22]. Due to the high level of moisture content, combustion promoters are usually used in order to improve the conversion efficiency. Coal is the most frequently used promoter, and co-combustion of biomass/biodegradable waste with coal has dominated the bioenergy production market in some countries, i.e. Sweden, Japan, etc. However, envi-

, SOx

efforts and costs to deal with so that the environmental influence is minimized.

are the major bottleneck for this method for bioenergy recovery [23]. Furthermore, as the common challenge of incineration plant, the flying ash is another pollutant that needs lots of

Thermochemical conversion utilizes constant and high temperature combined with catalysts to convert biomass inside the boiler to biofuel and bioenergy through changing their physical properties and chemical structure [24]. The main technologies of thermochemical conversion of biomass and biodegradable waste include pyrolysis, gasification, liquefaction and torrefaction [25], among which pyrolysis and gasification are considered the most promising ones [26]. Pyrolysis is a fundamental method to transform biomass into crude-like liquid bio-oil [27], and after the chemical decomposition, the liquid bio-oil can be converted to the combustion fuels mainly used for transport and chemical industry [28]. The principle of pyrolysis process is the combination of thermal and chemical decomposition with the help of catalysts at relatively lower temperature

C) and longer vapor residence time in absence of oxygen for converting the organic sub-

stances to liquid bio-oil with charcoal and gases as the by-products [24, 29]. Gasification is another important thermochemical technology that converts different kinds of biomass into syngas. The main composition of syngas is methane, hydrogen, carbon dioxide and carbon monoxide, which are extensively applied in space heating, power generation, transport and chemical industry [30]. Different from pyrolysis, gasification process requires relatively higher temperature (700–1300°C) with the absence or limited oxygen environment in order to optimize the production of syngas [23, 26]. Recently, with the technological development, the probability of biomass and biodegrad-

Biochemical conversion utilizes biological and chemical processes with the help of aerobic or anaerobic microorganism to transform biomass into biogas and bio-rest, and the main biochemical technologies are composting, anaerobic digestion and mechanical biological treatment (MBT). Composting is an aerobic digestion process and a popular method for the treatment of biomass and biodegradable waste (e.g. Finland). The basic principle is to use biochemical process with the help of aerobic microorganism under open air environment for converting biomass into environmentally friendly bio-rest, which can be used as fertilizer. Anaerobic digestion is the most popular biochemical technology for bioenergy production, and thousands of anaerobic digestion bioenergy production plants have been established all over the world [32]. Through the biochemical decomposition process with the help of anaerobic bacteria at constant temperature in the absence of oxygen, the biomass can be transformed into not only bio-rest but also energy-rich biogas [33]. Biogas is mainly comprised by methane (60%) and carbon dioxide (40%), and it is mainly used as vehicle fuels after cleaned and upgraded [34]. In

able waste gasification at lower temperature has also been discussed (e.g. [31]).

and NOx

, from the co-combustion process

ronmental challenges, i.e. emission of CO<sup>2</sup>

*2.2.2. Thermochemical conversion*

188 Energy Systems and Environment

*2.2.3. Biochemical conversion*

(450–600°

The concept of value chain was originally proposed by Porter from financial perspective to account the sequential value creation and appreciation through the whole network comprised by different companies and enterprises [37]. This concept is usually accompanied with another word with similar meaning: supply chain (i.e. in [38, 39]). The difference between those two concepts is sometimes negligible especially when the value creation and appreciation process over the material flow are predominately accounted. However, a recent study by Holweg and Helo [40] has explicitly distinguished the two concepts from the perspective of their focuses. Supply chain management focuses on the links and interactions among different companies from the operational level considering strategies, methodologies, design, planning and operation of an efficient and effective multi-stakeholder inner- and/or inter-company network. However, value chain mainly concerns the value-added activities from one company to another within the network and the opportunities and challenges for maximizing the overall value creation and appreciation through the whole network.

The value chain of bioenergy production from biomass and biodegradable waste has been extensively modelled in the literature. Balaman and Selim [41] proposed a biomass-to-energy value chain model and a decision support tool for maximizing the overall profit generated through bioenergy production. A simplified value chain model is developed by Parker et al. [42], and the primary target of the model is to improve the economic value of biofuel production from biomass. An et al. [43] formulated a computational model to optimize the overall profit of a lignocellulosic biofuel value-added chain. Kim et al. [44] developed a four-echelon value chain framework for biofuel production through fast pyrolysis conversion. The maximization of the overall value creation from bioenergy production is focused by Kim et al. [45] and Dal Mas et al. [46]. The maximization of the value creation is sometimes formulated in an opposite way that minimizes the system cost. Chen and Fan [47] formulated a bioethanol production value chain model that applies mixed integer programming for minimizing the overall system cost. Aksoy et al. [48] developed an optimization model for minimizing the transportation cost of bioenergy production from woody biomass and mill waste. The environmental benefits of bioenergy production have been increasingly focused in recent years. A value-added chain of bioenergy production from biomass is modelled by Lam et al. [49], which focuses on the mitigation of carbon footprint of bioenergy production.

product". The main technologies are gasification, pyrolysis, aerobic composting, anaerobic

A Value Chain Analysis for Bioenergy Production from Biomass and Biodegradable Waste…

http://dx.doi.org/10.5772/intechopen.72346

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• *Purification and upgrade of the generated bioenergy:* This step is a critical value-added process that converts the "semi-finished product" into "finished product". The biogas and bio-fuel produced from previous step cannot be directly sent to market due to their complex chemical composition and low efficiency, so thermal and chemical decomposition, purification and upgrade are necessary in this phase. Besides, the model aims at maximizing the value creation of bioenergy production, so the utilization of landfill gas is taken into account in

• *Distribution and sales of the bioenergy as well as other by-products in the market:* This is the final step of the value chain of bioenergy production, where the value creation from the bioenergy production is eventually realized. The biogas, bio-fuel and bio-rest can be used in many different sectors including transport, aviation industry, chemical industry, agricul-

Value chain analysis has been widely used for investigating, through qualitative and/or quantitative methods, the value-added process in many different fields, i.e. mining industry, fishery industry, aviation industry, dairy industry, catering, production and manufacturing, etc. Conventionally, value chain analysis only emphasizes the value creation and appreciation from financial point of view. However, the increased concern on environmental challenges has led to much more focuses on the "green value-added process" in which not only economic value creation but also environmental value contribution through the entire material flow is accounted (e.g. in [50]). Bioenergy production is a value-added process from both economic and environmental perspectives, so value chain analysis is a reasonable basis for regarding pro et contra for bioenergy production. The value chain of bioenergy production comprises all joints in the flow from materials to products, and it can be analysed in such a way that all important joints are balanced out of a combination of economic and sustainable

Value chain analysis of bioenergy production provides decision makers with fundamental basis to divert biomass and biodegradable waste from landfill to WTE process. Previously, the value of biomass and biodegradable waste does not get enough attention, and a large portion is treated through non-value-added method that leads to great potential environmental problems. The model streamlines the value creation and appreciation of bioenergy production from biomass and biodegradable waste, and both economic advantages and environmental benefits are discussed. Bioenergy production takes a different point from waste management perspective to consider biomass as the "raw material" of the value chain and realize the transformation from "waste" to "financial and environmental value". The utilization of biofuel and biogas can dramatically decrease the high dependency on fossil fuels and improve the energy security of a country; further, the nature of self-replenishment of biomass and biodegradable waste makes them become one of the most important renewable energy resources. Besides,

digestion, direct combustion and landfill.

ture, power generation and space heating.

aspects all the way from cradle to grave.

**3.2. Value chain analysis of bioenergy production**

this value chain model.

**Figure 4.** A general value chain model of bioenergy-from-biomass and biodegradable waste.

Bioenergy production from biomass yields economic benefits while reduces waste. However, it is not focused in the literature to account both economic and environmental benefits in the value chain of bioenergy production. In order to fill the literature gap, a general value chain model of bioenergy production from biomass and biodegradable waste is given in **Figure 4**. A typical value-added process of bioenergy production consists of the following activities:


product". The main technologies are gasification, pyrolysis, aerobic composting, anaerobic digestion, direct combustion and landfill.

