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A Series of Tubes Could Make It Practical to Get Fuel from Microörganisms
September 17th, 2012 by admin
September 17th, 2012 by admin
Monday, September 17, 2012
Joule Unlimited, a startup whose engineered microörganisms produce ethanol from sunlight, water, and carbon dioxide, announced the commissioning of a new demonstration plant last week that will start producing ethanol within the next few weeks. Today, the company announced a partnership with Audi that will help Joule develop and test its fuels. The financial details of the partnership weren’t released, but not including the Audi partnership, Joule has raised $110 million.
In small-scale outdoor tests, Joule has shown that its approach, which involves engineered microörganisms housed in special transparent reactors, could produce 8,000 gallons of ethanol per acre per year, a few times more than other advanced biofuels companies (see “TR10: Solar Fuel” and “A Biofuel Process to Replace All Fossil Fuels“). As Joule moves its technology to market, it has abandoned its original elaborate reactors in favor of simple plastic tubes—a move that Joule says makes the process more economical.
Most biofuels companies take some form of biomass, such as corn, grass, or algae, and process it to make biofuel, often with the aid of microörganisms. Joule’s approach is to take out as many of the intermediate steps as possible. Joule has taken a microörganism (the company won’t name the organism) and introduced combinations of genes known to produce ethanol from carbon dioxide and water and sunlight. To increase the productivity of the microbe, it has removed as many of the microörganism’s original genes as possible—without killing it—to ensure that its metabolism is geared toward making ethanol rather than growing the microörganism. Joule calculates that it could produce 25,000 gallons of ethanol per acre per year this way, and has demonstrated a rate of 15,000 gallons in the lab. It’s also developing organisms that produce diesel.
Crucial to this approach are the transparent containers, which Joule calls solar converters, used to grow the microörganisms. In its original design, these containers resembled solar panels—they were flat, thin, rectangular, and a couple of meters wide. They included channels for distributing water and carbon dioxide and collecting the fuel that the microörganisms excrete. They were designed to make sure that the microörganism gets the right amount of nutrients and sunlight without overheating. Partly to allow air to move over them to cool them, the panels were mounted on metal frames on concrete pads. “We saw very quickly that the design would not be cost-competitive,” says David Berry, a partner at Flagship Ventures, which founded Joule and has provided much of its funding.
Joule’s solution was to do away with the concrete foundations, metal frames, and solar-panel-like structures and use plastic tubes instead. The tubes are a couple of meters wide and up to 50 meters long. “The new design is much larger, and you can lay it directly on the ground. That leads to a huge reduction in cost,” says William Sims, Joule’s CEO.
In the new design, the organisms, nutrients, and water are circulated to optimize their growth. The ethanol they produce vaporizes inside the tubes in the sun, rising to the top, where it’s relatively easy to remove. (The ethanol still needs to be further purified in a central facility.) To deal with heat, the company uses a transparent resin for the tubes that redirects the infrared portion of sunlight away from the tube, while allowing the light the microörganisms need to pass through to them.
Joule plans to work out the final design for the system at its new four-acre demonstration plant in Hobbs, New Mexico. One of the challenges other biofuels companies face is that the economics of the process won’t work until it’s demonstrated in a full-scale commercial facility, with large vats for producing biofuel. Sims says the economics of Joule’s approach can be demonstrated with just a few of its plastic solar converters, reducing the amount of financing needed. “It’s pure replication. What works for four acres will also work for 5,000 acres,” Sims says.
Joule has calculated that its organisms could, in theory, produce 25,000 gallons of ethanol per acre per year, which would allow the company to produce ethanol at $1.28 per gallon. But Sims says the process could be economical at lower rates of about 11,000 to 12,000 gallons. He says construction on the first commercial plants could begin as early as the end of 2013.