Electrical bacteria are the key ingredient in a new process, which was developed by the Department of Energy’s Oak Ridge National Laboratory. They recycle waste-water from biofuel production, which is then used to generate hydrogen. This hydrogen can then be used to convert bio-oil into higher grade liquid fuels such as gasoline and diesel.
The team’s lab scale demonstration has the potential to produce 11.7 litres of hydrogen per day at rates that are required for industrial used. However, it has been noted that more work is required to bring the technology to the commercial scale. Although, the progress demonstrates the potential of microbial electrolysis to make bio-refineries more efficient and economically viable.
Abhijeet Borole, an ORNL research said “We are solving multiple problems at the same time” who led the multi-year project to develop the system. Microbial electrolysis is powered by electrogens - bacteria which digest organic compounds and generate an electric current. Borole put these bacteria to work in breaking down organic acids in liquid bio-oil that is produced from plant feedstocks such as switchgrass. Usually, a quarter of the liquid bio-oil is contaminated water which contains corrosive acids.
The hydrogen which is generated from the microbes could displace the need for natural gas in the future, which is used later in the production process to upgrade bio-oil into more desirable drop-in liquid fuels. They commented saying “We are taking this waste, which can be 20 to 30 percent of the biomass that you put in the process, making hydrogen from it and putting that hydrogen back into the oil, and the water can be recycled to produce clean hydrogen and eliminate the natural gas”.
The researchers developed a procedure to evolve and enrich a hardy bacterial community that could tolerate the toxic compounds that could tolerate toxic compounds in the biofuel waster. In this application, the bacterial poison comes in the form of products created by the degradation of lignin, a cell polymer found in plant cell walls. However, understanding how to build and optimize microbial electrolysis systems that can tolerate and treat contaminated wastewater could have benefits outside of the biofuel production industry. The research team is now focused on completing a life cycle analysis for the technology for evaluation purposes.