Generation of Electricity Using Biomass - Essay Example

Biomass by s s Biomass Introduction Energy is ified into two broad groups ly, non-renewable and renewable energy. Non-renewable energy is that type of energy that is generated from the sources, which are available in limited quantity on the earth, and will also vanish after some time (Liserre, Sauter & Hung, 2010). Non-renewable energy is not friendly to the environment and can, therefore, have severe effects on peoples’ health. These sources are referred to as non-renewable since it is not possible to regenerate them within a short time span. They occur in the form of natural gas, coal, fossil fuels, and oil. Renewable energy, on the other hand, is that type of energy that is obtained from natural sources such as wind, tides, sun, and rain (Liserre, Sauter & Hung, 2010). In addition, renewable energy can be generated continuously and when required. For this reason, renewable energies are available in abundance. They occur in the form of wind power, geothermal energy, and energy from tides, and biomass. The following explores the generation of electricity using biomass and looks at the advantages as well as the disadvantages of using biomass to produce electricity from non-renewable energy sources. Generation of electricity using Biomass Biomass is fuel, which is derived from organic materials (McKendry, 2002). It is renewable and, hence, a sustainable energy source that is used to generate electricity and other different forms of power. It is used for generation of electric power, facility heating, as well as for combined power and heat. Biomass as a term entails a wide range of materials, including agricultural residues, human and animal waste, and wood from different sources. Biomass can be transformed into electric power through numerous methods (McKendry, 2002). However, the most common method is direct burning of biomass material, like wood materials or agricultural waste. Other methods include anaerobic digestion, gasification, and pyrolysis. Different methods are applied with varying kinds of biomass. Woody biomass materials such as wood chip, sawdust and pellets are gasified or combusted to generate electricity. Gasification yields a synthesis gas that has usable energy by burning the biomass with limited oxygen compared to that required for complete combustion (McKendry, 2002). Wheat straw and corn stove residues are compressed and combusted or changed into a gas by the use of an anaerobic digester. Anaerobic digestion yields a renewable natural gas after organic materials are decomposed through the action of bacteria in a place devoid of oxygen. Wastes that are very wet, such as human and animal wastes, are changed into a gas that contains medium energy, also in an anaerobic digester. Additionally, majority of the other forms of biomass can be turned into bio-oil that can in turn be used in furnaces and boilers, through pyrolysis. Pyrolysis produces bio-oil by heating the biomass rapidly in a place devoid of oxygen. Most biopower industries employ direct combustion systems (McKendry, 2002). Here, biomass is burnt directly to generate high-pressure steam which in turn drives a turbine and a generator to produce electricity. In some biomass plants, the used or extracted steam is also used in manufacturing activities or heating buildings. A simplified biomass electric production system consists of several major components. It includes a combination of items such as fuel storage equipment, combustor, boiler, steam turbine, condenser, generator, fans, pumps, cooling tower, system controls, and exhaust. Direct combustion system supplies a biomass feedstock into a furnace or a combustor, where this biomass is combusted with surplus air to heat water in the boiler to generate steam (McKendry, 2002). The steam from this boiler then undergoes expansion through a turbine that rotates to drive a generator and hence produce electricity. The process is shown in the figure below. Figure 1: Direct combustion of biomass (Wbdg.org, 2015) All biomass systems require fuel storage space as well as some form of fuel handling controls and equipment (Rentizelas, Tatsiopoulos & Tolis, 2009). A silo or a bunker is used for short term storage. For larger storage, an external fuel yard is used. An automatic control system transmits the fuel from the external storage region using a combination of stackers, front-end loaders, cranes, belts, pneumatic transport, and augers. Manual equipment such as front loaders may be used to convey biomass to the bunkers from the piles. Exhaust systems emit the by- products of combustion to the environment. Electrostatic precipitators, multi-cyclones, or baghouse may be used as emission controls (Rentizelas, Tatsiopoulos & Tolis, 2009). Depending on the properties of the fuel, emission regulators for unburned oxides of nitrogen, hydrocarbons, and sulfur may be needed. Advantages of using Biomass Compared to non-renewable energy, biomass has a number of advantages. First, it is dispatchable. This implies that it can be controlled and is available when needed. Secondly, biomass has low carbon emission and, hence, is environmental friendly. However, biomass has some disadvantages when used to generate electricity. For instance, the fuel has to be procured, paid for, delivered, and stored (Hassuani, Leal & Macedo, 2005). Although these amounts to expenses, they are still relatively economical compared to if non-renewable energy sources are used. In addition, combustion of biomass yields emissions that have to be carefully controlled and monitored to obey regulations. For instance, when burned, biomass emits atmospheric pollutants such as greenhouse gasses. Using biomass for electricity generation, therefore, causes air pollution (Hassuani, Leal & Macedo, 2005). This occurs in the form of carbon dioxide, carbon monoxide, nitrogen oxides, particulates, volatile organic compounds, and other pollutants. Black carbon is also produced when biomass is burned and causes global warming. Disadvantages of using Biomass With the emissions coming from the combustion systems, biomass can affect air quality (Zhang et al. 2009). These emissions vary and are dependent on the biomass resource and the conversion technology. However, since most biomass resources contain less mercury and sulfur than coal, biomass plants, in general, give off less of these pollutants. Sulfur emissions cause acid rains and smog while mercury is a common neurotoxin. Gasifying and burning of biomass emits carbon into the environment (Zhang et al. 2009). With the increasing interest in climate change and renewable energy, scientists are placing the carbon emission by biomass under severe scrutiny. In the process, they strive to make significant distinctions between beneficial biomass resources and those that would enhance net emission. Also, in case crops are not replanted, then biomass becomes a non-renewable resource. Moreover, the set of biomass fuels may have severe environmental impacts (Zhang et al. 2009). For instance, harvesting timber or growing farming products for fuel needs large volumes to be gathered, transported, manufactured, and stored. These biomass fuels can be found from supplies of uncontaminated and clean wood which would otherwise be used for other purposes. However, compared to the collection of fossil fuels, the net environmental effects of biomass are less. Still, the gathering, processing, and burning of biomass fuels can cause detrimental environmental impacts (Zhang et al. 2009). For instance, the fuel source may contain toxic pollutant. Also, handling of agricultural wastes may pollute water sources such as rivers and streams. In addition, burning biomass may deprive the local ecosystem of the valuable nutrients that would have otherwise been provided by agricultural wastes or forests. Conclusion Therefore, if done well, biomass energy can bring many environmental benefits. Predominantly, using biomass energy in generating electricity may reduce several kinds of air pollution as well as net carbon emission. Biomass can be harvested in a manner that protects the quality of soil, maintains the wildlife habitat, and avoids erosion. However, these environmental benefits of using biomass are dependent on creating biomass resources that are beneficial while avoiding the harmful resources (McKendry, 2002). This, therefore, calls for policies which can guide these activities. In addition to its numerous environmental benefits, using biomass to generate electricity offers energy security and economic benefits. For example, it reduces the call for importing fossil fuels from other nations and states. This in turn, reduces the country’s expenses as well as exposure to disturbance in that supply. Since biomass technologies employ combustion processes to generate electricity, it can then be produced at any time. Biomass energy technology plays a critical role in reducing the quantity of carbon dioxide emission into the atmosphere. In doing so, it contributes to a decrease in the greenhouse effect. Biomass use is, therefore, clean and possesses a relatively smaller effect on the environment compared to non-renewable energy sources. Biomass can also not be exhausted, unlike the non-renewable energy sources like fossil fuels and crude oil. References HASSUANI, S. J., LEAL, M. R. L. V., & MACEDO, I 2005, Biomass power generation. Sugar cane bagasse and trash. 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