Growing diesel?

A Cambridge Mass based biotech company, Joule Unlimited, claims that it has genetically engineered an organism (cyanobacteria) that can produce ethanol or diesel directly from photosynthesis. These cyano bacteria are encapsulated in flat panels exposed to sunlight and supplied with water (such as non-potable water that otherwise would be unusable) and "industrial waste" CO2. That's it, no feedstock is required. This is in contrast to using algae in ponds that require input of other nutrients and produce triglycerides that must be reacted with methanol to produce diesel esters. Joule plans to build a ten acre demonstration facility will be built this year. Technical details are provided in the journal Photosynthetic Research.

Joule Unlimited's panel system containing diesel-producing cyanobacteria (click for larger image).

Joule claims that the process can produce 15,000 gallons of diesel per acre annually. Its not clear if this an acre of land occupied by the units or acre in surface area of the units (which would then take up more than a physical acre of real estate).  The Energy Information Agency reports that in 2009 the United States consumed 1,159,558 thousand gallons of low sulfur fuel oil distillate (diesel and fuel oil). To replace that amount with this process would require approximately 120 square miles of these photosynthetic generators, which is not a huge amount of real estate in the U.S. Burning this biodiesel would still produce CO2, but since this new process consumes the gas and presumably requires little energy from other carbon dioxide producing processes, supposedly it would not contribute much to global warming.

I have to admit, this sounds too good to be true. Assuming that this process indeed works, there are still many questions. How much infrastructure is required? Are the organisms really this efficient? Do they really only require not much more than sunlight, carbon dioxide and water? How robust are the organisms? What is the true amount of EROEI?

If this process works as claimed it would indeed by revolutionary. Which would be appropriate, since the company is located in Massachusetts. Take that Texas!