Cyanobacteria that Crap Ethanol
by Jeremy Elton Jacquot, Los Angeles on 09.16.07
For those of us who toil in marine biology, these are exciting times: we've known now only for a few years that populations of cyanobacteria in the open oceans contribute significantly to nitrogen fixation and total biological productivity. In fact, they are in large part responsible for supplying the nitrogen used by phytoplankton to conduct photosynthesis. Cyanobacteria such as Trichodesmium and Synechocystis have thus become hot research subjects in the field.
Given their abilities (and relative abundance), it is perhaps not surprising that some enterprising marine scientists have already been investigating their potential in the production of alternative energy sources. Pengcheng (Patrick) Fu, a professor of bioengineering at the University of Hawai'i, has devised a way to turn carbon dioxide into ethanol by using a combination of cyanobacteria and sunlight.
By successfully transforming two genes from a fellow cyanobacterium, Fu and his colleagues were able to engineer a specific strain of Synechocystis that emits ethanol as waste upon using carbon dioxide and sunlight. With his new startup - SUNOL Biotechnology (that we encountered at Wired Nextfest) - Fu hopes to be able to build a large-scale ethanol plant within the next 2-3 years.
In addition to removing carbon dioxide directly from the atmosphere, Fu envisages using the cyanobacteria to pull it out of power plant emissions, helping to prevent further GHG release into the atmosphere and slowing the onset of global warming.
Via ::Reality Sandwich: Cyanobacteria to The Rescue (blog)
See also: ::Heat-Seeking Bacteria Could Hold Key to Better Cellulosic Ethanol, ::You Got Bacteria in My Gas: Engineering Microbes to Make Hydrocarbons
Image courtesy of WIRED
Cultured varieties of yeast generally can hit 7 - 14% alcohol in the solution before they stop growing. At that point in alcohol production, most of the effort and energy is to purify the alcohol, either by membrane separation and/or distillation. Starting from say a few percent will end up being much more energy intensive. Wondering what these cyanos can get to before they self poison.
Using CO2 from power stations, would, if they were burning natural gas or coal, not diminish their CO2 output unless the ethanol were put in long-term storage. I take it the idea is to burn the ethanol for mechanical power. In that case, the previously buried carbon released as CO2 from the power plant would in fact be adding to the amount of atmospheric CO2. The point is that it would be doing more in the process of increasing atmospheric CO2 - it would have helped generate electricity, then helped power a motor car. That's better, but it does not lead to a reduction in atmospheric CO2.
If Fu pulls CO2 out of coal or natural gas burning power plants, and gets the cyanobacteria into ethanol to be used as a fuel, then previously stored CO2 is still going to be released into the atmosphere, and GHG emissions will be less only to the extent that the ethanol is replacing fossil fuel use.
So you may get more 'bang' for your previously stored CO2, but you are still converting that CO2 into atmospheric CO2, and increasing GHG emissions.
Better than nothing, but we must be careful about how we understand proposals to use flue gasses from power stations to create combustible fuels.
Cyanobacteria have a potential for all sorts of biotechnology. They produce a large variety of bioactive compounds, including substances with anti-cancer and anti-viral activity, UV protectants, specific inhibitors of enzymes, and potent hepatotoxins and neurotoxins. Only a few biosynthetic pathways have been elucidated. More info on the Microbiology Blog
It'll be interesting to see if the future can turn this technology into something that could power a craft at sea without needing to return to a fuel dock.