1
Biomass - An Environmental Concern

Deepak S. Khobragade

Datta Meghe College of Pharmacy, Datta Meghe Institute of Higher Education and Research, Sawangi (M), Wardha, India

1.1 Introduction

Any biological organic matter derived from living or dead organisms can be called "biomass." Every type of biomass is directly or indirectly obtained from the photosynthesis process [1]. Thus, biomass is a natural material with an organic matrix obtained from plants and animals [2]. It encompasses various materials, like wood, agricultural and industrial remains, and animal and human waste. Due to its range, there are substantial differences in biomass composition, whether of industrial or domestic origin [3]. With this vast heterogeneity in the usage and origin of materials, the definition of "biomass" varies. There is a wide range of biomass materials that can be broadly grouped as raw or derived. Cellulose, hemicelluloses, lignin, starch, and proteins are some of the main elements of biomass [4-7]. Various biomass sources of diverse origins, like agricultural, forestry, industrial, and other sources, are presented in Table 1.1 and depicted in Figure 1.1.

Biomass is now primarily used for feed, followed by food, and finally for the production of energy, fuels, and chemical feedstock. It accounts for 13% of global final energy consumption (other renewables contribute another 5%). The industrial organic chemical sector produces 550 million tonnes of chemicals and 275 million tonnes of nitrogen fertilizer, but the chemicals contain only 500 million tonnes of carbon. Furthermore, organic compounds used in organic chemistry contain approximately 100 million tonnes of carbon [8]. Currently, sugar, starch, and vegetable oil are the primary sources of biofuels and biochemicals [9]. Consumers interest and the need for replacement of fossil fuels with renewable energy sources are driving up demand for bio-products. The price level of feedstocks, such as lignocellulose, sugars, starch, and oils, is another factor influencing the competitiveness of biochemical products [9]. Price comparisons of bio-based carbon to fossil-based carbon, as well as cost comparisons of processing bio-based materials with the corresponding fossil-based materials, are difficult to specify because they are dependent on raw materials and the molecular economy of the processes into the final products. The various advantages and disadvantages of biomass are depicted in Table 1.2.

Table 1.1 Sources of biomass.

Figure 1.1 Types of biomass and examples.

Table 1.2 Advantages and limitations of biomass use.

Table 1.3 Biomass classification.

• Fuel in itself
• Heat and electricity generation
• Biogas generation
• Fermentation for producing chemical products like alcohol and biodiesel
• Manure as by-product

Mineral oil is refined to produce fossil fuels and basic chemicals with very high carbon efficiency and low labor intensity. In contrast, biomass necessitates more processing steps, which increase the cost and labor requirements (see bioethanol production). Renewable energy sources such as solar, wind, hydro, and geothermal energy, as well as nuclear energy, are carbon-free in the energy industry. The transportation sector accounts for one-third of total final energy demand and 23% of global energy-related CO2 emissions. Oil products meet approximately 96% of global transportation energy needs, with the remainder being met by electricity and biogas; thus increased use of renewables in the transportation sector is a high priority in the decarbonization of this sector.

The use of biofuels and other renewable energy sources, such as solar and wind, can help decarbonize the transportation sector [10]. The EU and the US have set limits on food-based biofuels. Although only 2% of global land is used for biofuel feedstock production, the "fuel versus food" debate shows that biomass used for industrial purposes is a sensitive issue in society. Some feedstocks (e.g. maize, oilseeds, sugarcane, and vegetable oil) have relatively high demand: biofuels consume 20% of global sugarcane, 12% of global vegetable oil, and 10% of global coarse grain production. Because biofuel accounts for a very small proportion of overall land use changes, crop competition may be reduced (as a percentage of total final energy consumption). Renewable energy sources play a critical role in the economy's "decarbonization," or the process of reducing the amount of greenhouse gas (GHG) emissions produced by the combustion of fossil fuels. These sources are called biomass only if they cannot be reused for subsequent processing [11]. The classification of biomass is presented in Table 1.3.

1.2 Biomass as an Energy Source

Factors that determine the usage of fuel are (i) cost, (ii) accessibility, (iii) stove type and technical features, (iv) cooking practices, (v) cultural preferences, and (vi) awareness about the potential health impacts [12]. Biomass is available on earth in many places, like agriculture, domestic farms, forests, and oceans. The total biomass reserves on land are estimated to be around 1.8 trillion tons, with an additional 4 billion tonnes in the ocean. Biomass is an enormously significant energy source, available everywhere, and bioenergy is the energy generated from biomass. About 33?000 EJ of energy can be produced by the total biomass present in the world. It is more than 80 times the total annual energy requirement of the world. Currently, biomass provides about 14% of the basic energy requirements of the world, i.e., 56.9 million exajoule per year globally (1230 million tonnes of oil equivalent per year) [8, 9]. About 159 billion liters of biofuel are produced each year globally from various biomass sources.

Solid biomass (wood, shrubs, herbs, wood chips, wood pellets, and other biomass sources) provides the majority of household biomass supply (85%). Biomass-based liquid biofuels contribute 8%, municipal and industrial waste contribute 5%, and biogas makes up a meager 2% of the total biomass supply. The utilization of biomass is not equal around the world. In some underdeveloped and...