Increasing fossil fuel price has caused the implementation of various renewable energy sources for example biomass energy. Biomass is plant materials or organic matters from industrial, domestic and municipal waste. Biomass energy is stored solar energy which can be converted to electricity, fuel or heat. In this case, photosynthesis of plant is the initial step of converting light to chemical energy. There are four techniques to generate biomass energy which are direct combustion, pyrolysis, gasification and fermentation. Industry, homes, businesses and transportation are the biggest users of biomass energy. Biomass produces much less pollution compared to fossil fuel emission. However, it requires a lot of land as most of biomass energy comes from plant material. This will lead to an increase in global food price if biomass becomes the primary energy as the resources come from food material.
Energy consumption and demand is increasing tremendously worldwide. Many countries rely on fossil fuels such as coal, oil and natural gas as their main sources of energy. These fossil fuels are finite resources and most regions in the world have to import these energy sources to meet the demands of the growing population.1 This has resulted in a surge in the price of fossil fuels in recent years. This phenomenon has triggered the need to utilize renewable energy sources that are sustainable.2 One of the popular and environmental friendly renewable energy sources is biomass.3 Biomass can be defined as organic matters that can be obtained either directly from plant materials and vegetation; or indirectly from industrial, domestic and municipal waste3. Generally, biomass can be divided into two categories which is biomass wastes and energy crops. Biomass wastes are simply forestry residues, farming and animal residues, sewage waste and organic municipal waste. Examples of biomass wastes include food waste, paper, corn stalks and dying trees. On the other hand, energy crops are crops which are farmed specifically for their fuel value.6 For instance in the United Kingdom, the Energy Crop Scheme (ECS) offers Short Rotation Coppice (SRC) and Miscanthus.1 “SRC is a densely planted, high-yielding varieties of either willow or poplar, harvested on a 2 to 5 year cycle, although commonly every 3 years. “SRC is a woody, perennial crop, the rootstock or stools remaining in the ground after harvest with new shoots emerging the following spring. Miscanthus crops are woody, perennial, rhizomatous grasses, which can be harvested annually for at least 15 years.”1 Photosynthesis by plants is the crucial step for capturing and storing solar energy. These plants can be then used as fuel source. Photosynthesis is the process whereby carbon dioxide and water are used to produce carbohydrates and oxygen in the presence of light and chlorophyll.1 In this case, solar energy is converted to chemical energy that can be used later to produce energy. Biomass is currently responsible in providing 14% of the world’s primary energy supplies. In the forth coming century, biomass has the potential of providing up to 50% of the world’s energy supplies.1 Moreover, biomass energy is more environmental friendly compared to coal combustion as it creates minimal greenhouse gases and does not contribute much to global warming. Even in Malaysia, the government is looking into utilizing biomass as an energy source. 9“The empty fruit bunch (EFB) from oil palm can easily
generate 5% to 10% of the country’s total energy requirements in an environmentally friendly and sustainable manner,” says M. Umakanthan, a power plant expert in Malaysia. 9 Thus it can be concluded that biomass is indeed a viable option of energy that is both environmental friendly and able to meet the demands of increasing energy demands. Biomass project has gained its popularity in many countries nowadays because of the current energy demand. The type of technology being used, the size of the power plan and the cost of the supply will affect the cost of electricity generation. In order to save cost, the sources need to be located near to where it will be used. Biomass energy has been widely used currently and its feasibility has been proven through the many benefits that it brings to human being and nature. Amongst the many usages of biomass are for generating electricity, industrial processes and fuel for vehicles. A wide range of technologies have been researched and developed to utilize biomass. Generally, the applications of biomass energy can be divided into direct and indirect uses13. Direct use involves the direct combustion of biomass sources to produce energy. On the other hand, indirect uses include fermentation, gasification and pyrolysis. In direct combustion, biomass sources like wood will be combusted to produce fire and heat for cooking, lighting as well as water and space heating. This application is rather simple and approachable because it does not need any complicated processes as compared to the indirect uses. This technique is rather similar to combustion of coal but it does not bring any major negative effects to the environment. Moreover, the generation of electricity will be more efficient if biomass is mixed with coal in combustion11. This is because the coal will help to increase its net calorific value (CV) and thus produces more energy. Combustion systems used in burning biomass can range from small stoves to high voltage combined heat and power (CHP) systems. In addition, biomass with low moisture content is especially suitable for direct combustion as it uses a small amount of energy to evaporate the water content 14. Pyrolysis is a basic thermo-chemical process that decomposes organic material in the absence of oxygen. In this technique, solid biomass is converted to liquid fuel or bio-oil. These bio-oil can then be used in oil-fired burners to generate electricity and heat.14Pyrolysis usually involves heating solid biomass under pressure at 800oF. In real practices, it is quite impossible for pyrolysis to operate in the absence of oxygen as oxidation occurs. The heating process forces volatile or semi-volatile substance out of the
biomass, leaving behind a small portion of solid biomass or char. The volatiles are gathered and treated in a secondary thermal oxidation unit to produce bio-oil. Solid char has a higher CV and it is generally smokeless when combusted. The next type of biomass technology is gasification which involves contacting solid biomass with hot steam to produce gaseous fuel which is known as synthesis gas. The synthesis gases contain 70% to 80% of the energy originally present in the solid biomass.16 This gas can be burned for heating, electricity production, or may be further converted to act as a substitute for almost any fossil fuel. The main advantage of gasification is its innate ability to control pollutants. Besides that, gasification is capable of producing multiple products including synthesis gases, liquid fuels and hydrogen. Amongst the organizations that recognized gasification technique is California Energy Commission & California Integrated Waste Management Board and U.S. Environmental Protection Agency, Office of Solid Waste.14 Lastly in fermentation, yeast is added to sugar containing biomass and the mixture is allowed to ferment. During the fermentation, gases are produced and these gases are used to turn turbines which in turn generate electricity. The solid waste residue from this process can also be used as fertilizers.11 Biogas that is being produced from the wastes in landfills and marshes need to be burned in order to produce electricity. Other than burning, the waste can also go through anaerobic composting process that will form electricity. Usually, when biogas has been upgraded, it can directly be use in powering vehicles. For instance, bioethanol has become popular and commercially used in many countries such as United Kingdom, Sweden and Brazil. 10 The fuel that is produced from the crops like sugarcane, hemp and maize can be used in vehicles if it is mixed with petrol13. The most popular biomass fuel is biodiesel where it is more efficient than diesel. Besides it can be use in diesel engines, it also very environmental friendly when it emitted less CO2 and SO2 to the atmosphere.12 Biomass is different from the other forms of fuels since biomass requires land to grow on. Therefore, it creates a lot of controversial issues like by whom and how the land should be use for the biomass energy purpose.18 There are two suggested main approaches to decide on land use for biomass. One of them is by identifying the need, biological source and considering the possible environmental effect. However, this approach was not being
undertaken resulting in the ignorance of expertise of local farmers who understands the local condition best, leading to many biomass project failures. The other approach is “multiuses” approach which can be undertaken to recognize how land can be used for sustainable development by considering what mixture of land use and cropping patterns. Biomass wastes generate air emissions (NOx, and CO2) just like the other fuel waste.21 In fact, it is proven that biodiesel gas emits relatively high CO2 compared to fossil fuel. However, CO2 can be converted into oxygen through the photosynthesis process. Further technology on biomass resource could reduce on air emission as to establish biomass as a new energy source that is 100% environmentally friendly. Since biomass energy is derived from plant materials such as cornstalks, sugarcane remains, and coconut shells, when Europe and America decided to make it compulsory to include biofuels in their energy mix, global food price have dramatically increased. It is being argued that energy-crop program compete with food crops in many ways such as; rural investment, skilled labor, fertilizers, infrastructure and water usage. Thus, it is important to practice an appropriate agricultural activity with further research in order to prevent increasing in global food price. Although the world’s interest in biomass is increasing, the development of the biomass energy is still hindered by various factors; one of them is that a biomass-based plant is costly to build. Currently, the best biomass-based power plants with a thermal efficiency of about 40 percent cost approximately US$2000 per kilowatt of electricity to build; however a large scale coal-fired stations with a thermal efficiency of about 45 percent cost only US$1500 per kilowatt. Therefore, more research is needed to develop a more efficient and lower cost system. In addition, such system should be further characterized with fuel upgrading, combustion and cycle improvement, sophisticated biomass preparation and conversion. 24 Another important consideration for the future biomass-based system is the flue gases treatment. A better flue gases treatment such as flue-gas condensation not only recovers the heat of the flue gases but would also capture dust and hazardous pollutants from the flue gases. Basically, most dioxins, chlorine, mercury, sulfur oxide and dust can be removed to some extent by using flue-gas condensation. Furthermore, in order to achieve maximum fuel flexibility and fuel supply security, biomass cofiring with coal is taken into
consideration for future biomass energy production. This technology could also increase the supply or quality of biomass and is cost effective.24 From current view, the conversion of biomass to ethanol would be one of the most important applications of biomass energy in the future. However, the development of this application is still limited as it is economically uncompetitive and environmental unfriendly as compared to other forms of renewable energy. Recently, research shows that ethanol fermentations could be improved by using lignocellulosic biomass as the substrate. It is assumed that the cost of this technology will be as low as US$0.13/litre of ethanol as compared to using corn starch. Nonetheless, the key problem of this technology is that a long time is needed for enzymatic saccharification. (FAO Corporate Document Repository, 2009)22
Biomass has the potential to grow and supply for energy. There are two types of uses for biomass energy which are direct and indirect uses. Industry, homes and businesses, and transportation are the biggest user of biomass energy. In Malaysia, the government is planning to use EFB to generate energy. Biomass releases CO2, NOx, but it is not as bad as compared to fossil fuel emissions. However, biomass energy required a lot of land as most of the biomass energy source are from plant materials. Global food price will also increase when biomass becomes the primary energy to the world as most of biomass resource comes from food material.More research on biomass energy need to be done to develop a more efficient and less costly system.
Figure 1:Taken from: http://www.malignani.ud.it/WebEnis/NorthWind-SouthSun/power/Biomass.htm
Figure 2: Taken from Biomass (2008). The Need Project. Intermediate Energy Infobook, pp.8-9
Figure 3: Taken from http://en.wikipedia.org/wiki/Gasification
Figure 4: Taken http://upload.wikimedia.org/wikipedia/en/7/7b/Reactor_.jpg)
Figure 5: Taken from Biomass Energy-Part of a Sustainable Future? (n.d.), Retrieved March 1,2009 from http://www.alternate-energy-sources.com/biomass-energy.html
Figure 6: The experimental Fluidized-bed Combustion System at Penn State University integrated with a 2 million Btu/h watertube boiler to recover heat from the flue gases (figure taken from http://www.energy.psu.edu/facilities/images/researchboiler.jpg, 2009).
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