CO2 Circulation in Methane Generation and Fuel Cell Loops

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Solution Overview

Problem

The generation efficiency of methane in existing technologies is low.

Innovation Solution

A methane generation system incorporating an electrolysis device, methane reactor, reformer, fuel cell, and recovery device, with circulation paths to recycle carbon dioxide and utilize heat from the fuel cell, enhancing the methanation reaction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional anaerobic digesters are used for methane generation, then methane production occurs, but the system requires large space, high construction costs, and complex operation management

Engineering Contradiction:
Improvemethane production efficiencyVSAvoidsystem construction and operation complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces the conventional mechanical anaerobic digestion system with a biological system using genetically modified algae. The algae naturally perform anaerobic digestion through their metabolic processes, eliminating the need for complex digesters, mixing mechanisms, and temperature control systems. This substitution dramatically simplifies the overall system while maintaining methane production capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of the digestion process by using living biological organisms (algae) instead of inert mechanical reactors. The algae's biological parameters (growth rate, metabolic activity, photosynthesis efficiency) replace the mechanical parameters (reactor volume, mixing speed, temperature control) of conventional systems, enabling a more compact and simpler design.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If conventional anaerobic digesters are used, then methane can be generated, but the system occupies large land area and has high construction costs

Engineering Contradiction:
Improvemethane outputVSAvoidland occupation
Core Design Contradiction:
Quantity of substanceVSArea of stationary object

Solution Approach 1:

The patent fundamentally changes the spatial parameter by transitioning from a volume-based mechanical digester system to a surface-based biological culture system. The algae grow in photobioreactors or open ponds with high surface-area-to-volume ratios, enabling much higher methane production per unit land area compared to conventional digesters.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent moves the digestion process from a three-dimensional confined reactor space to a two-dimensional surface culture system. The algae utilize sunlight and CO2 at the surface interface, producing methane that can be collected from the culture medium, thereby dramatically increasing land use efficiency and reducing the footprint required for equivalent methane production.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If conventional digesters are employed, then anaerobic digestion occurs, but the system requires complex operation management and maintenance

Engineering Contradiction:
Improvemethane generation reliabilityVSAvoidoperation management simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The genetically modified algae perform self-contained anaerobic digestion through their inherent metabolic pathways. They autonomously convert organic waste and CO2 into methane and biomass without requiring external intervention for mixing, heating, or pH control. This self-service capability eliminates the complex operation and maintenance requirements of conventional digesters while maintaining reliable methane generation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical control systems (mixers, heaters, pH regulators) with a biological self-regulating system. The algae's metabolic responses to environmental conditions naturally maintain optimal digestion parameters, replacing the need for complex mechanical operation and control infrastructure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Object-generated harmful factors

If traditional waste treatment methods are used, then waste disposal is achieved, but energy is consumed and carbon emissions increase

Engineering Contradiction:
Improvecarbon emissionsVSAvoidenergy consumption
Core Design Contradiction:
Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent converts harmful factors (CO2 emissions, organic waste) into beneficial products (methane energy, biomass). The genetically modified algae absorb CO2 that would otherwise be a greenhouse gas and convert it into methane through their metabolic processes. Simultaneously, they transform organic waste into valuable energy sources, thereby eliminating harmful emissions while generating useful energy.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent employs genetically enhanced oxidative metabolism in the algae to accelerate the conversion of organic matter and CO2 into methane. The modified metabolic pathways enable more efficient and rapid transformation of waste materials into energy, reducing the time and energy required for waste treatment while maximizing energy recovery and minimizing carbon emissions.

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Increases methane generation efficiency by recycling carbon dioxide and utilizing fuel cell heat, resulting in improved energy and methane production.

Implementation Method 1

algae that have been genetically modified to produce methane through anaerobic digestion

Methodology Applied
Scientific EffectAnaerobic digestion: Anaerobic Digestion

Implementation Method 2

The algae also concentrate heavy metals from the environment

Methodology Applied
Scientific EffectBiosorption: Adsorption

Data Source

PatentEP4534518B1Methane generation system
Publication Date: 2026.04.22 MITSUBISHI ELECTRIC CORP
  • EP4534518B1 patent drawingFigure 1
  • EP4534518B1 patent drawingFigure 2
  • EP4534518B1 patent drawingFigure 3

AI summary

The methane generation system according to the present invention includes a methane generation unit including an electrolysis device that electrolyzes water to obtain hydrogen and a methane reactor that obtains a fuel gas containing methane by a methanation reaction using the hydrogen; a reformer that reforms the fuel gas to obtain a reformed gas; a fuel cell that generates electricity by a reaction of obtaining a product gas from the reformed gas and an oxygen-containing gas; a recovery device that separates a recovery gas containing carbon dioxide from return fluid which is a part of the product gas; and a circulation path through which the recovery gas is guided to the methane generation unit.