From PhD thesis to prototype to pilot plant. And, then, hopefully, to a full-fledged operational system.
At least that’s the hope of Dr. Alex J. Lewis and his thesis advisor, Abhijeet P. Borole. And, Alex (and Abhijeet) did the standard academic exercise, converting a PhD thesis into multiple publications (6 of them)- plus the all-important patent applications to protect the concept and allow for commercialization.
What they have is a fuel-cell like (a microbial electrolysis cell, MEC) system populated with microbial species that can convert organic (actually, they are focusing specifically on food, right now) wastes into hydrogen gas. This means they can convert carbonaceous materials into a carbon-free renewable fuel (and, I’m pretty sure into carbon-heavy methane [the fuel in natural gas]). Moreover, this means that the wastes don’t end up in landfills, which is where most of the 1.3 billion tons of food waste ends up each year. (Moreover, many of these landfills also emit methane gas, as the organic wastes are eaten by microbes- and that is a potent greenhouse gas.) If all of this food waste was converted to hydrogen, 26 million metric tons of hydrogen could be produced.
In a normal microbial fuel cell (MFC), the organic materials are converted to protons and electrons (plus carbon dioxide [at the anode]). These protons and electrons then migrate to the anode where the hydrogen is combined with oxygen to produce water and electrical power.
These folks developed what they call an MEC, which has a ‘deoxygenated’ anode (no oxygen). This means the MEC will produce neither water nor electrical power. Instead, hydrogen gas is produced at the cathode. (The MEC also requires the application of external voltage on the cathode and anode, so it uses rather than produces electricity for use.) The device has anodes, anoxic or anaerobic cathodes (and a conductive wire connecting the two) with an ion-permeable “membrane” separating the two battery parts- and microbial populations.
This MEC requires pretreatment of the wastes (the wastes are macerated and liquefied) before the waste is fed to the microbial reactor. The microbes grow on one side of the alternating battery (anodes and cathodes) stacks. One set of microbes digests (breaks down) the organic wastes into metabolites that then are further treated by another microbial population. And, as we discussed the other day, that microbial population is electrogenic- capable of passing electrons outside their cellular bodies. These released electrons then combine with the protons (also known as hydrogen ions) at the cathode to produce hydrogen gas. (There also is a gas purification system to remove gases other than hydrogen in the product.)
Let’s hope the pilot plant proves the economics of the system. It would be great to stop all that food waste from filling up our landfills!
I’m enjoying all your recent science reports that give us hope of a brighter future-if our society doesn’t self destruct first. I am so concerned at the lack of basic knowledge in our population, especially those who don’t understand even the basics of why the research you blogged about today is so important-and necessary.
Thank you so much, Alana! I, too, worry about our political future. A recent cartoon said it all- Instead of a stately Lincoln on his chair in the Memorial, he has covered his face with his arm and has shrunk down.