The tubular baffled reactor and its potential for the biological methanation of carbon dioxide

Abstract

The biological Power to Methane process (PtM) is gaining ground as an answer to the long-term renewable energy storage problem. Methane is an efficient hydrogen carrier, has an established worldwide transport infrastructure and can serve as a link between renewable power generation and a circular carbon economy. One of the defining factors regarding the scalability of the PtM process is the design of the reactor as it can determine the production rate/energy expenditure ratio. The tubular baffled reactor, a popular reactor design within the chemical industry has been assessed in the present study as a biomethanation reactor for the first time. The experiments were conducted with mixed cultures and the results point to high gas-liquid mass transfer capabilities as indicated by the methanation rates achieved (>90 % CH4 at 270 L/L/d mixed gas input rate). The gas/liquid flow ratio appears to have a stronger effect on methanation than the gas residence time. The working length of the reactor determines the pressure drop experienced by the culture, with higher pressure drops showing a negative correlation to methanogenesis.