Improved biological methanation using tubular foam-bed reactor

Area of Science:

• Biotechnology and Bioengineering
• Renewable Energy Storage
• Chemical Engineering

Background:

• Power-to-gas technologies are crucial for integrating renewable energy but face limitations.
• Hydrogen (H₂) transfer into the liquid phase is a rate-limiting step in biomethanation.
• A novel tubular foam-bed reactor (TFBR) was developed to overcome this limitation.

Purpose of the Study:

• To investigate the performance of a novel tubular foam-bed reactor (TFBR) at laboratory scale.
• To enhance the rate-limiting H₂ transfer in biomethanation.
• To assess the reactor's efficiency in producing grid-quality methane.

Main Methods:

• Development and testing of a novel tubular foam-bed reactor (TFBR).
• Addition of a non-ionic polymeric surfactant (Pluronic® F-68) to stabilize liquid foam.
• Experimental phases at mesophilic (40°C) and thermophilic (55°C) conditions, including intermittent H₂ feeding.

Main Results:

• Addition of surfactant increased gas-liquid surface area and bubble retention time.
• Biomethane production rate (MPR) increased 6.5-fold to 15.1 [unit] at 40°C with >90% CH₄ concentration.
• MPR reached 29.7 [unit] at 55°C, demonstrating robustness even under intermittent H₂ supply (14.8 [unit]).

Conclusions:

• The TFBR accelerates biomethanation technology for renewable energy storage.
• The reactor demonstrates robust performance and reliability, even under H₂ starvation.
• TFBR systems are suitable for biotechnological processes limited by gas-liquid mass transfer.