Burning Man, Burning Microbe: Biofuels beyond Biomass
by Jim Lane (Biofuels Digest) …Are they biofuels? We think so – even if they are post-biomass. They do what organisms have done for eons to make biomass in the first place: convert lifeless CO2, sunlight and water and nutrients into a new material.
Today, there are four classes of technologies that directly create a fuel without first making a biomass.
Post-biomass sugar fermentation In this class of technologies, the organism directly produces a fuel from a sugar and, if the sugar is made via synthetic biology rather than extracted from biomass, it is a post-biomass path.
…Post-biomass sugar, that’s what Proterro is working on. Proterro’s microorganism synthesizes sucrose from sunlight, CO2, nutrients and water. They are in the process of training the microorganism to make it fast enough to be a viable technology at industrial scale. If it works – that a post-biomass substrate from which other magic bugs can produce a huge array of fuels and chemicals. Without digging them up from the ground, or using land or sea to grow biomass.
Gas fermentation In this class of technologies, the microorganism ferments synthesis gas – or syngas, a combination of hydrogen and carbon monoxide – into an alcohol. The syngas can be made by gasifying biomass – but it can also be made directly from, say, methane emissions or natural gas.
There are five technologies that, broadly speaking, have this capability today. Coskata, INEOS Bio, LanzaTech, Siluria and, as a part of its hybrid liquid-gas fermentation process, Zeachem.
…Solar fuels In this class of technologies, the microorganism directly produces a target alcohol or alkane – using sunlight, CO2, water and nutrients – and then secretes it into a chamber from which it can be extracted from the liquid medium in which the microorganism lives.
There are two technologies around today that have this broad capability. There’s Algenol and there’s Joule.
…Electrofuels In this class of technologies, they are not only post-biomass, they are post-sunlight. Generally speaking, they operate much the same as the solar fuels – excepting that the microorganisms draw energy from electricity instead of from sunlight. The underlying current can, of course, be supplied by a variety of post-biomass sources, including hydro, wind, solar or even natural gas. READ MORE