Clean Power solar cyborg bacterium

Published on January 8th, 2016 | by Tina Casey


Moorella The Solar Powered Cyborg Turns CO2 Into Something Useful & Good

January 8th, 2016 by  

Yes, it’s a thing. Solar energy can be used to transform the greenhouse gas carbon dioxide into useful chemical products. CleanTechnica has been following a number of these “artificial photosynthesis” systems through the R&D phase and we just caught wind of a new one from Lawrence Berkeley National Laboratory that involves a cyborg bacterium with a name that sounds like a scream queen from the glory days of the B movie: Moorella thermoacetica.

solar cyborg bacterium

Another Nail In The Coffin Of Carbon Sequestration

Before we take a closer look at M. thermoacetica, let’s step back and look at the implications for the carbon sequestration movement. Sequestration adds a significant category of waste to the growing pile that future generations will eventually have to deal with in one form or another, so it doesn’t really solve a problem, it simply shoves it aside.

More to the point, sequestration can be prohibitively expensive — look what happened to FutureGen — and in the case of underground storage a sequestration facility could be exposed to disruption from emerging conditions and episodes such as drought or earthquakes.

As capably demonstrated by the ongoing leak from a large natural gas storage facility in California, external disruption is not the only risk faced by underground storage systems, and all bets are off when facility owners make irresponsible decisions.

As one indicator of where things are going in the US, the Department of Energy recently pulled the funding rug out from under the FutureGen sequestration project while pumping up the carbon recycling company LanzaTech.

Moorella And Solar Energy

That brings us back to solar energy and M. thermoacetica. This particular bacterium is actually not photosynthetic, but the research team got it to perform photosynthesis by doping it with nanoscale particles of the semiconductor cadmium sulfide, which explains the “cyborgian” aspect as described by lead researcher Peidong Yang:

By inducing the self-photosensitization of M. thermoacetica with cadmium sulfide nanoparticles, we enabled the photosynthesis of acetic acid from carbon dioxide over several days of light-dark cycles at relatively high quantum yields, demonstrating a self-replicating route toward solar-to-chemical carbon dioxide reduction.

As for M. thermoacetica, this particular bacterium is highly efficient at producing acetic acid through photosynthesis, to the tune of almost 90 percent. The result is a cyborg system that is almost as efficient as natural photosynthesis. Compared to fully artificial photosynthesis systems, the hybrid system has the potential for lower costs, partly due to the advantage of biological self-assembly and repair.

You can get more details from the study under the title “Self-photosensitization of non-photosynthetic bacteria for solar-to-chemical production” in the journal Science.

Commercializing Carbon Conversion

Speaking of LanzaTech, the Energy Department is mainly interested in the company for the development of a bio-based method for converting methane to a transportable liquid, through an initiative called REMOTE.

The main target is fossil natural gas but there could be potential to apply the process to biogas as well. In particular, the Energy Department has tasked LanzaTech with developing small-scale systems that could be used economically at remote natural gas drilling sites, so we’re thinking that it could also be used at livestock farms and other facilities that can produce biogas.

Meanwhile, LanzaTech is also barreling down the road to commercializing its fermentation based gas-to-products system for recycling waste carbon, so stay tuned.

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Image: via Berkeley Lab.


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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • JamesWimberley

    “Sequestration adds a significant category of waste to the growing pile
    that future generations will eventually have to deal with in one form or
    another, so it doesn’t really solve a problem, it simply shoves it

    You are wrong on several counts.

    1. We probably don’t have a choice. Current CO2 concentration is 400 ppm, and we are seeing all sorts of scary effects. The 2 degree Paris limit may correspond to 550 ppm, but probably lower; we are very likely to overshoot (link). Hansen says both are unsafe: we should get back to 350 ppm, which is still higher than pre-industrial. So we will need to sequester carbon, by the gigatonne.

    2. Do not confuse the general concept of sequestration with the attempts at it through liquefaction of CO2 at coal power stations and injection into geological formations, generally and misleadingly known as CCS. This does not work at acceptable cost and almost all pilots have been abandoned.

    3. The need remains. There are far better candidates nowhere near power stations: weathering of the superabundant silicate mineral olivine; biochar burial; and simple reafforestation, which needs no new technology.

    4. Deep geological burial of biochar at subduction zones is just a thought experiment, but it does show that genuinely long-term sequestration on geological timescales is feasible in principle. Sequestration on shorter time-scales is worth having. I’ve made a case here (link to blog) with Mike O’Hare of Berkeley for increasing construction in wood from sustainable forestry. Timber houses, office blocks and furniture sequester carbon for a century before release back to the atmosphere, buying time for a definitive solution.

    • Otis11

      I agree with what you’ve said, but that doesn’t change the fact that the vast majority of anything burned and sequestered will eventually have to be taken care of by some future generation. Or did I miss something?

      • JamesWimberley

        Not necessarily. The accelerated weathering of olivine proposed by Schuiling would generate large volumes of bicarbonate ions in solution, which would in time be turned into carbonates by corals and other marine organisms and eventually limestone. This sequestration would be definitive on timescales of interest. Limestone subducted into the Earth’s mantle at collision lines between tectonic plates is eventually heated and the carbon released as carbon dioxide through volcanoes, but that is a very long-term cycle (millions of years), and we have much earlier problems to deal with.

        • Otis11

          But, can we be sure that the bicarbonate ions being turned into carbonates by corals are not replacing other sources of carbonaceous materials the coral might otherwise use?

          My guess here is simply that there’s no free lunch. Any alteration we induce will be fought by the system trying to maintain equilibrium… something that we must eventually yield to. Every attempt to delay it is that much more a future generation must make up for. (But then again, this is getting far enough out there that we don’t have good data yet… let’s hope!)

          • Pol Knops

            The coral will use the bi-carbonate. Unfortunately will some CO2 be released in the process of forming carbonates.
            But very general speaking is the process of enhanced weathering merely speeding up the natural sink (just as we increased the CO2 sources). A Dutch guy from the NIOZ is preparing an article about this.
            And indeed this sequesters CO2 for a geological period of time (in contrast with trees 😉 ).
            Best regards,
            Pol Knops

          • Otis11

            Thanks for the reply Pol.

            I understand that the coral will use the bi-carbonate, but my point is, the coral was going to create a set amount of carbonates anyway. With the extra bi-carbonate, the amount of carbonates they build might increase slightly, but by and large, we will saturate their demand for bicarbonate and therefore be replacing another generation method.

            These systems are all in balance. We can nudge them a little, but try and push too hard and they’ll push back somewhere else…

  • Marion Meads

    “As for M. thermoacetica, this particular bacterium is highly efficient at
    producing acetic acid through photosynthesis, to the tune of almost 90

    I think that this statement needs to clarified as to the basis of efficiency. Is the efficiency based from Solar Radiation Interception, or is it based from sugars to acetic acid? I know for a fact that conversion of sugars to acetic acid is in the 90% or more conversion efficiency range and I am suspecting that this was the basis. A 90% conversion of solar energy into the energy of acetic acid is a NOBEL PRIZE breatkthrough, and would be impossible even for a hybrid physical and biological system!!!

    • Joseph Dubeau

      ” The result is a cyborg system that is almost as efficient as natural photosynthesis. ”

      Natural photosynthesis can convert 1% of sunlight into energy.
      I’m wondering about the 90% , 90% of what?

      • Marion Meads

        Precisely! 90% of what.

        The best plants in the world have 5% sunlight to biomass energy, and it occurs only during particular times of the year. The best year round average of these plants is slightly less than 3%. For the majority of the plants, it is more like 1% yield of biomass energy.

        About 95% of the sunlight energy absorbed by the plants is lost through evapotranspiration, a necessary evil to bring the stream of nutrients into the plants.

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