Published on July 2nd, 2014 | by Tina Casey3
EPA Approves First Bug That Eats CO2, Spits Out Ethanol
July 2nd, 2014 by Tina Casey
The brave new world of next generation biofuel has pushed the US Environmental Protection Agency into some strange new places. The agency has just given the thumbs-up to a genetically modified bacterium from the company Joule, which brings us one giant step closer to next generation biofuels made from sunlight and carbon dioxide.
New Bacteria For Next Generation Biofuels
The basic idea behind biomass-derived fuel is to cut out the middleman (because fossilization takes forever, right?) and make photosynthesis go directly to work.
If you start at corn ethanol and work your way up the sustainability ladder to next generation biofuels, the top-of-the-line example would be algae biofuel. That process typically involves exposing algae to light, and shunting some of the algae’s carbon intake off to produce oil.
That’s all well and good but the oil half of the equation typically involves considerable mechanical and chemical intervention for harvesting and refining, and that’s where Joule sees room for improvement.
Instead of algae, Joule’s “industrial photosynthesis” model is based on a proprietary strain of cyanobacteria. Although commonly referred to as blue-green algae, cyanobacteria is not an algae. It is a single-cell bacteria but it does live in water and forms colonies visible to the naked eye, hence the misnomer.
Along with our sister site PlanetSave we’ve previously taken note of cyanobacteria’s role in next generation biofuel (here and here, for example), but we have seriously undersold its unique role on Earth, so now would be a good time to play catchup. Here’s an enthusiastic rundown on cyanobacteria from UC-Berkeley (breaks added):
They have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact!
Many Proterozoic oil deposits are attributed to the activity of cyanobacteria.
They are also important providers of nitrogen fertilizer in the cultivation of rice and beans.
The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.
The other great contribution of the cyanobacteria is the origin of plants. The chloroplast with which plants make food for themselves is actually a cyanobacterium living within the plant’s cells.
Industrial Photosynthesis For Next-Generation Biofuels
With those factoids in hand, let’s take a closer look at Joule’s process. Basically the cyanobacteria act as a self-replicating catalyst, continuously taking in CO2 and converting it directly into liquid fuel.
Normally, all of that carbon would go into cell growth, so that’s where Joule’s modification comes in. The company’s cyanobacteria are engineered with a “carbon switch” that at a certain point in the organism’s growth shunts nearly all of the carbon into fuel production.
Here’s what the industrial photosynthesis process looks like as described by Joule (breaks added):
The direct process uses a cyanobacterial platform organism engineered to produce a diesel-like alkane mixture, to maximally divert fixed CO2 to the engineered pathway, and to secrete the alkane product under conditions of limited growth but continuous production.
…Such processes, where cells partition carbon and free energy almost exclusively to produce and secrete a desired product while minimizing energy conversion losses due to growth-associated metabolism, have much longer process cycle times and higher system productivities.
Speaking of engineering, Joule’s portfolio actually includes a “library” of tailorable catalysts, each designed for a specific output. That includes drop-in ethanol under the moniker Sunflow-E (E for Ethanol, right?), Sunflow-D (that would be the diesel version), and other alternative chemicals that can sub in for petrochemicals.
Aside from the cyanobacteria, CO2, and sunlight, the process does require water, which could be a sticky wicket these days. However, Joule’s process is designed for non-potable water, which should help to mitigate water resource issues.
On The Road To Commercial Next Generation Biofuels
If you’re wondering how the EPA factors into this, the agency is responsible for approving something called MCAN, for Microbial Commercial Activity Notice. Didn’t know we had one of those, did you? Neither did we.
MCAN filings are a required step before a company can put a modified microbe into commercial operation. The EPA approval applies to Joule’s demonstration facility in Hobbes, New Mexico. As part of the approval, Joule will share data from the operation with EPA.
As a commercial demonstration facility, Joule aims for Hobbes to prove that it can produce “in minutes what conventional oil takes millions of years.” The company projects that a 10,000-acre industrial photosynthesis plant would produce the equivalent of a mid-sized oil field with a reserve value of 50 million barrels.
Joule’s system is also scalable to dovetail with local sources of waste CO2.
The MCAN approval is quite a step up from the last time we checked in on Joule. That was about four years ago, before the Hobbes facility was built.
If all this is ringing some bells you’re probably thinking of another company we’re following, LanzaTech, which has been going hammer and tongs at waste gas conversion from the microbial fermentation side.
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