(資料來源：Masse et al., 2011)
Manure to Energy: Exploring Energy Production via Animal Waste
There is a third form of agricultural waste which can be utilized for energy production which is often forgotten: animal waste. With meat production being the large industry it is today, there is a huge amount of unharnessed potential in this waste; but instead of utilizing the energy, is often left to build to toxic levels. Animal waste is a major pollutant, and will lead to severe environmental problems if not managed properly. In fact, manure often leads to water and land degradation, greenhouse gas emissions, nutrient loss, and human and environmental health (Masse et al., 2011). By creating a bioenergy system that can use this waste product, the amount of pollution will decrease while energy is produced in a more sustainable manner: a win-win situation.
(Source: Masse et al., 2011)
Biogas is a sustainable and carbon neutral source of energy, making the harvest of manure for energy production a viable option (Masse et al., 2011). Treated manure is not just used for energy production, but rather is a multifunctional product. When treated, it breaks into solids, liquids, and gases, and each part can be used in a beneficial way. Solids can be used as fertilizer for agricultural fields, keeping nutrients within the system, liquids can be treated to use in irrigation or cleaning,and the gases are left for energy production (Far Eastern Agriculture, 2013). The solid leftovers, when used as fertilizer, emits less nitrogen gases into the atmosphere than other fertilizers, and therefore reduces the amount of greenhouse gases produced (Masse et al., 2011). The sustainable removal and treatment of this waste also drastically reduces disposal costs, and helps to manage the odors associated with animal farming (Ahn et al., 2009).
While the waste of all animals can be used in biogas production, swine waste was proven to be the most efficient, both in terms of amount produced and period of viable production (Ahn et al., 2009). Taiwan raises pigs in substation numbers, but until recently, the waste produced was released untreated into the environment where it created environmental and health problems (Far Eastern Agriculture, 2013). Since the country produces vast quantities of pig manure, it makes sense that they look into the possibilities of biogas for energy production.
One of the largest incentives to biogas is the long-term cost. While initial costs are expensive, they would help to mitigate the governments future financial responsibilities associated with cleaning up waste after is has become a problem (Far Eastern Agriculture, 2013). Changhua Country’s Dongluo treatment plant was the first to be funded by a local government in order to reduce the overarching costs of waste treatment (Far Eastern Agriculture, 2013). Following the success of this first plant, other governments and companies in Taiwan have looked towards developing their own waste to energy technologies (Yang and Lee, 2015). While many of the small scale farms may not be considered, it is believed to be economically feasible for any facility raising at least 5,000 pigs, which Taiwan has over 100 of, to use this energy conversion technology (Yang and Lee, 2015).
There are also ways to create a more effective biogas plant, including combining manure with agriculture waste or industrial food waste (Masse et al., 2011). This would help to reduce the amount of waste in landfills releasing emissions and unnecessarily taking up space (Masse et al., 2011). Another option for co-firing is using animal carcasses with manure, which, barring major diseases with heavy fatalities, is a viable option of removing bodies without worrying about contamination to the ground, water, or spreading sickness and creating nutrient problems (Masse et al., 2011).
As with other forms of bioenergy from agricultural waste, one of the major concerns is safety for bystanders. Until it has been proven that any harmful bacterias are controlled and eliminated prior to processing, it is unlikely to become a common energy source (Masse et al., 2011). Some of the other barriers include cost of operation and cooperation required in order to create the best system for all (Masse et al., 2011). Without government cooperation, the cost of developing efficient technology is too high with too long of a payoff period for it to be feasible for most farmers (Masse et al., 2011). Therefore the government needs to be willing to play an active role in bioenergy production. However, it is equally important that energy companies and other industries cooperate to create the best system (Masse et al., 2011). This is in order to ensure that bioenergy is more cost effective and will produce better economic opportunities in the future.
- Ahn, H.K., M.C. Smith, S.L. Kondrad, J.W. White. (2010). Evaluation of Biogas Production Potential by Dry Anaerobic Digestion of Switchgrass–Animal Manure Mixtures. Applied Biochemistry and Biotechnology. 160(4), 965–975.
- Far Eastern Agriculture. (2013). Taiwan builds plant to turn pig waste into biogas. http://fareasternagriculture.com/live-stock/pig/taiwan-builds-plant-to-turn-pig-waste-into-biogas
- Masse, D.I., G. Talbot, Y. Gilbert. (2011). On farm biogas production: A method to reduce GHG emissions and develop more sustainable livestock operations. Animal Feed Science and Technology. 166–167, 436-445.
- Yang, S. and Lee, M. (2015).Turning pig manure into electricity. Focus Taiwan News Channel. http://focustaiwan.tw/search/201512050023.aspx?q=