Proof of Concept

Proof of concept

Introduction

Our concept is to generate methane from biomass and use it as energy.For this proof of concept, we did the following

Our project to use E. coli to produce acetic acid is highly novel, and is a major step forward in the use of synthetic organisms for the future biogas market.

Current situation

Methane production using biomass is currently in the process of being utilized worldwide, and there are several actual examples of this being done.

  1. Methane fermentation
    The mechanism is shown in the figure below.

    Methane fermentation is carried out using a complex microbial system.It is estimated that 70% of the methane produced in this methane fermentation is derived from acetic acid. Disadvantages in this fermentation pathway include

    • Decomposition efficiency and speed
    • Sustainable utilization of methanogenic bacteria

  2. Methanation
    In Japan, a technology called methanation has been attracting attention in recent years.The mechanism is shown in the figure below.

    One of the reasons why this methanation has not been widely used in Japan is the instability of hydrogen supply. In methanation, hydrogenotrophic methanogenic bacteria are used.

Proposed Implementation

The system we envision is a new environmentally friendly power generation platform that will be built through collaboration among barns, power companies, and government agencies. We have obtained that cost-effectiveness is important in the implementation. Details are provided in the Proposed Implementation.

Human Practice

When considering the issues in methane fermentation using microorganisms, we thought that hydrolysis reactions would not be effective because of the existence of marketed formulations. We also confirmed that manure is used to generate electricity by methane fermentation at livestock farms through feedback from swine barns. The disadvantage of this process was that the microorganisms used were only available for one month. More details can be found in Integrated Human Practice.

Prototype

Based on the above, we focused on acetic-acidic methanogenic bacteria. The issues to be solved in this thema are the increase in the rate of acetic acid production by the fermentation pathway and cost-effectiveness. Therefore, we modeled a fermentation pathway in which acetic acid is produced from glucose by Escherichia coli. In addition, we considered that it would be cost-effective to use manure as a raw material in the future, since methane fermentation equipment is planned to be installed in each barn.In Japan, it is calculated that methane fermentation at $0.26*10^6 Nm^3/y/万人$ is feasible, so it is necessary to develop a methane fermentation process that exceeds this value.

Experiment

Future Prospects

Methane is a greenhouse gas. Therefore, in addition to biological containment, it is necessary to develop equipment and mechanisms to utilize the methane produced by fermentation without leaking it into the atmosphere. In addition, since the end users are general consumers, such as ranchers, it is necessary to introduce a coloring system that allows visual recognition of microbial concentration and acetic acid production.

Refarence

1.Selective Immobilization of Aceticlastic Methanogens to Support Material, J. Soc. Powder Technol., Japan, 43, 653-659 (2006)
https://www.jstage.jst.go.jp/article/sptj1978/43/9/43_9_653/_pdf
2.Methane Production from Biomass Wastes by Anaerobic Fermentation (First step), Proposal Paper for Policy Making and Governmental Action toward Low Carbon Societies
https://www.jst.go.jp/lcs/pdf/fy2013-pp-05.pdf
3.Biological Purification Processes for Biogas Using Algae Cultures: A Review
January 2015International Journal of Precision Engineering and Manufacturing-Green Technology 4(1-1):20-32
https://www.researchgate.net/publication/270884936_Biological_Purification_Processes_for_Biogas_Using_Algae_Cultures_A_Review
4.環境省：メタンガス化の技術
https://www.env.go.jp/recycle/waste/biomass/technical.html

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