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Friday, March 29, 2013

Biofuel from atmospheric CO2 via a 'Rushing Fireball'

Making a more efficient biofuel may be part of the solution to tackling climate change. Biofuels are essentially carbon neutral, first capturing carbon dioxide through the plant photosynthesis process which is then released when the fuel is burnt. But processing the plant biomass sugars to a fuel that can be used is an inefficient process that can perhaps be improved upon.

Michael Adams, a Professor in Biochemistry and Molecular Biology from the University of Georgia, is researching micro organisms that live near deep ocean volcanic vents, in particular Pyrococcus furiosus, or "rushing fireball," This little single celled anaerobic critter feeds on carbohydrates in the super-heated ocean waters near geothermal vents at temperatures around 100C. It has proven adept at carrying out many basic chemical processes with it's enzymes stable at the high temperatures of it's environment.

Pyrococcus furiosus is a member of the hyperthermophilic Archaea family of creatures and was only discovered relatively recently by Karl Stetter in 1986 in deep sea vents and volcanic marine mud off the coast of Italy.

Michael Adams and his team have manipulated the organism's genetic material to enable it to feed on carbon dioxide at much lower temperatures, about 72C.

By using hydrogen gas they can create a chemical reaction in the organism that incorporates the carbon dioxide into 3-hydroxypropionic acid, a common industrial chemical used to make acrylics and many other products. Perhaps a way to sequester carbon in a stable form.

The Research team think that with other genetic manipulations of this new strain of Pyrococcus furiosus, they can generate a host of other useful industrial products, including fuel, from carbon dioxide.

"This is an important first step that has great promise as an efficient and cost-effective method of producing fuels," Adams said. "In the future we will refine the process and begin testing it on larger scales."

By using this particular micro-organism the researchers have perhaps found a more efficient way to produce biofuels without going through the photosynthesis process of absorbing carbon dioxide by plants or algae to make into biofuels.

The sugars manufactured by plants in the photosynthesise process and locked away in cell walls can prove difficult to efficiently extract to turn into biofuel.

"What this discovery means is that we can remove plants as the middleman," said Adams, who is co-author of the study detailing their results published March 25 in the early online edition of the Proceedings of the National Academies of Sciences. "We can take carbon dioxide directly from the atmosphere and turn it into useful products like fuels and chemicals without having to go through the inefficient process of growing plants and extracting sugars from biomass."

Here is the full abstract to the paper by Matthew W. Keller et al - Exploiting microbial hyperthermophilicity to produce an industrial chemical, using hydrogen and carbon dioxide:

Microorganisms can be engineered to produce useful products, including chemicals and fuels from sugars derived from renewable feedstocks, such as plant biomass. An alternative method is to use low potential reducing power from nonbiomass sources, such as hydrogen gas or electricity, to reduce carbon dioxide directly into products. This approach circumvents the overall low efficiency of photosynthesis and the production of sugar intermediates. Although significant advances have been made in manipulating microorganisms to produce useful products from organic substrates, engineering them to use carbon dioxide and hydrogen gas has not been reported. Herein, we describe a unique temperature-dependent approach that confers on a microorganism (the archaeon Pyrococcus furiosus, which grows optimally on carbohydrates at 100°C) the capacity to use carbon dioxide, a reaction that it does not accomplish naturally. This was achieved by the heterologous expression of five genes of the carbon fixation cycle of the archaeon Metallosphaera sedula, which grows autotrophically at 73°C. The engineered P. furiosus strain is able to use hydrogen gas and incorporate carbon dioxide into 3-hydroxypropionic acid, one of the top 12 industrial chemical building blocks. The reaction can be accomplished by cell-free extracts and by whole cells of the recombinant P. furiosus strain. Moreover, it is carried out some 30°C below the optimal growth temperature of the organism in conditions that support only minimal growth but maintain sufficient metabolic activity to sustain the production of 3-hydroxypropionate. The approach described here can be expanded to produce important organic chemicals, all through biological activation of carbon dioxide.

Promising stuff. But still early days. Every now and again I come across interesting research which shows some promise in providing a small part of the solution to the problems posed by climate change. Many may never prove successful, practical or cost effective, but we still need to research the different potential solutions and develop the ones that prove effective. This little critter may be called upon to make the biofuel for your car sometime in the future.


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