Study of LCA application in the energy systems focused on the Anaerobic
Digestion Gas (ADG)
Jeerayoos Tantiwiwat*, Helmut Yabar, Yoshiro Higano, Takeshi Mizunoya
University of Tsukuba, Graduate School of Life and Environmental Sciences, Japan; 1-1-1
Tennodai, Tsukuba, Ibaraki, Japan 305-8572*jeerayoos_7@hotmail.com
At present, the environmental problems associated with human activities are gradually causing severe
impact to mankind. Especially important is the huge dependence on fossil fuel as energy source. To address
this challenge many renewable energy sources have been developed. However, while these alternatives havethe image of being environmental friendly, if we measure their footprint from a life cycle perspective theymight be still causing great impact on the environment. In this study we analyze a new type of renewableenergy technology namely Anaerobic Digestion Gas (ADG) by using Life Cycle Assessment as well as Life
Cycle Costs in order to determine the feasibility of this technology. The study proposes different scenarios andcompares their performance in two stages: fuel source and power generation methods. The study compares theperformance between the utilization of ADG or other type of biomass source and between the utilization of fuelvia traditional thermal power generation method and via the fuel cell.
Anaerobic Digestion Gas (ADG) is the product of the anaerobic digestion process. Anaerobic digestion
is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen.
This method has been used for industrial or domestic purposes to manage waste and/or to release energy andalso been widely used as part of the wastewater treatment process. The ADG is considered as the renewable
fuel because the process produces a methane and carbon dioxide rich biogas suitable for energy production.
The feedstock sources are typically biodegradable waste such as human bodily waste, agricultural waste or
food processing waste, which can be found in our daily life and cause the environmental problems at present
due to their difficulty of disposal and treatment. This is also benefitting in reduction of CH4, one of thegreenhouse gases, emitted to the atmosphere if the biodegradable waste decays on its own. Moreover, ADG canreplace fossil fuels in energy conversion devices and the solid residue, the nutrient-rich digestate, also can beused as fertilizer. And for the utilization of ADG, I want to focus on the fuel cell, especially Molten Carbonate
Fuel Cell, which directly converts the hydrogen source through chemical reaction to generate the electricitypower.
In the case of the application of the ADG and fuel cell utilized systems the study uses data from thebiomass utilization, especially in biomass waste such as livestock manure and wastewater sludge, and also thefuel cell utilization in Japan. The evaluation is done in terms of global warming potential, ozone depletion andacidification, other environmental factors and also material and energy consumption from a life cycle
perspective. We will also analyze the financial cost in capital and maintenance cost, then the feasibility to apply
these types of energy systems. The calculation process will be done via the software for calculating in terms ofLife Cycle Assessment. As the result, we can pinpoint the main problems and be able to reduce the impact andalso improve the efficiency of the energy system. Finally the feasibility study can lead to promote theutilization and distribution of energy systems utilizing fuel cell and ADG to help realize a sustainable andenvironmental-friendly energy system.