I still have some childhood memories in my mind, when I travelled the rural areas of Pakistan, I could see the number of cow dung cakes pasted on the walls all around the village. Lots of questions came in to my mind, why the people of villages do so? Is it beneficial or is it unhealthy? Later I came to know the amazing properties of cow dung as a biofuel. So, I choose this topic to discus here. Globally the demand of fuel in terms of transportation and power generation is increasing day by day. These have so far been met largely from the stock of fossil fuel such as crude oil, which is finite in nature. Fossil fuels are not environmentally friendly and are also expensive. The use of alternative and more environmentally-friendly energy sources such as biogas has been advocated.
Cow dung is considered as an excellent biomass for second generation biofuel. Each year, Dairy farms around the world generate billions of tonnes of dung. Cow dung can be used for both electricity and fuel. In both applications, the concept behind energy production is the collection of methane gas that is a product of manure. Because methane is the primary gas that is turned into energy when burning natural gas, there is a huge potential for collecting methane gas from cow manure. In the process of production of biogas, anaerobic digestion takes place with anaerobic bacteria (or) fermentation of biodegradable materials in the absence of oxygen. It primarily consists of carbon dioxide methane and small amounts of hydrogen sulphide, siloxanes,and moistures. The gases methane, carbon monoxideand hydrogen can be oxidized with oxygen. This energy which is released allows biogas to be used as a fuel, purpose of heating and also can be used in a gas engine for the purpose of converting the energy into electricity and heat. (Muthu et al., 2017).
Cow manure as energy not only interests dairy farms, but the idea has also interested car company Toyota. The company has plans to build a power plant that turns the methane from cow manure into hydrogen and power for electricity. The hydrogen in particular could be used to fuel Toyota’s fuel cell hydrogen cars. The plant will also produce enough power to sustain over 2000 homes and fuel for 1500 cars (Howard., 2017).
Fig 1: Carbon dioxide closed cycle for biogas (Noor et al., 2014)
Biofuel produced by cow dung has many advantages. It reduces greenhouse gas emissions, and is therefore climate friendly. It allows us to manage animal waste. Produce a stabilized residue that can be used as a fertilizer, thus it can slash our import bill for LPG and chemical fertilizer. (Korbag et al., 2020)
Besides having the various advantages, biofuel produced by cow dung have some limatitations and disadvantages as well. An unfortunate disadvantage is the lack of efficient system for the production of biogas. There is a need to develop new technologies that can simplify the process so that biogas is available at low cost and in abundance. Biogas contains impurities even after refinement and compression. If the generated bio-fuel was utilized to power automobiles, it can corrode the metal parts of the engine. This corrosion would lead to increased maintenance costs. Weather is another factor that can affect the production of biogas. Bacteria need an optimum temperature of 37°C to digest the waste material. In winter seasons, heat energy is required to maintain the temperature of a digester that leads to an additional maintains cost. Biogas generation by using cow dung depends on the availability of raw material that is plentiful in rural and suburban areas only (Khayal., 2019).
Muthu, D., Venkatasubramanian, C., Ramakrishnan, K., & Sasidhar, J. (2017, July). Production of biogas from wastes blended with cowdung for electricity generation-a case study. In IOP Conf. Series, Earth Environ. Sci, 80(1), p 012055. https://iopscience.iop.org/article/10.1088/1755-1315/80/1/012055/pdf
P. W. Howard, “Toyota to Build Power Plant to Convert Cattle Manure into Electricity, Hydrogen,” USA Today, 30 Nov 17. http://large.stanford.edu/courses/2017/ph240/xiao-m2/
Noor, M. M., Wandel, A. P., & Yusaf, T. (2014). MILD combustion: the future for lean and clean combustion technology. International Review of Mechanical Engineering, 8(1), 251-257. https://www.researchgate.net/publication/261173547_MILD_Combustion_the_Future_for_Lean_and_Clean_Combustion_Technology
Korbag, I., Omer, S. M. S., Boghazala, H., & Abusasiyah, M. A. A. (2020). Recent Advances of Biogas Production and Future Perspective. In Biogas. IntechOpen.93231 https://www.intechopen.com/online-first/recent-advances-of-biogas-production-and-future-perspective
Khayal, O. M. E. S. 2019. Advantages and limitations of biogas technologies. https://www.researchgate.net/publication/336414255_ADVANTAGES_AND_LIMITATIONS_OF_BIOGAS_TECHNOLOGIES