The BioCat Project uses an advanced alkaline electrolyzer and an optimized biological methanation system to generate renewable gas for the direct injection into a local 3-bar gas distribution grid.
The BioCat Project uses an advanced version of Hydrogenics’ S1000 alkaline electrolyzer. The electrolyzer is connected to the local power grid and draws electricity in times of low electricity prices, which is an indication of a supply/demand imbalance. In four different cell stacks, the electricity splits water into its molecular components hydrogen and oxygen. Both gases are immediately separated and leave the electrolyzer in separate pipes. The hydrogen is then delivered to the methanation reactor, while the oxygen is supplied to the activated sludge basins for wastewater treatment.
Due to its fast response time, the electrolyzer is able to provide frequency regulation services to the local power grid. It does so by adjusting its power intake (i.e. increasing or decreasing electricity consumption) in response to an automated signal. The signal is triggered whenever the frequency in the grid approaches the upper or lower frequency boundary.
In Electrochaea’s biological methanation system, the hydrogen from the electrolyzer is combined with carbon dioxide, and this gas mixture is then introduced to a liquid phase methanation reactor. Over the course of the experimental testing phase in the BioCat Project, two sources of carbon dioxide will be used: (i) raw biogas from an adjacent anaerobic digester with a composition of approximately 60% methane and 40% carbon dioxide, and (ii) a pure stream of CO2 supplied by an on-site biogas upgrading system.
Inside the bioreactor, a culture of methanogenic archaea metabolizes the hydrogen and carbon dioxide to methane. Archaea are single-celled organisms (prokaryotes) that have evolved over billions of years in harsh environments. The specific strain used by Electrochaea’s methanation system has been selectively evolved (not genetically modified) in the laboratory of Prof. Laurens Mets at the University of Chicago and exhibits properties ideal for applications in industrial environments. Those properties include:
- Low energy metabolic pathway from carbon dioxide to methane
- Very high carbon mass conversion efficiency
- High tolerance to contamination (oxygen, hydrogen sulfide, particulates)
- Moderate operating temperatures (60-65°C)
- High selectivity in product gas (100% methane, no intermediate products)
- Low catalyst operating costs enabled by self-maintenance and self-replication
- Very high responsiveness (ability to cycle on/off within seconds)
Gas Injection System
The renewable gas produced by the BioCat facility will be analyzed for grid-specification (molecular composition, heating value, Wobbe number, etc) downstream of the methanation reactor before it is injected into a 3-bar gas distribution grid. Being the principal component of natural gas, methane can be injected into the natural gas network in a practically unlimited manner. Once in the grid, the gas can be used for electricity production, as a transportation fuel in CNG-enabled vehicles, or as a heat source in household and industrial applications.