Published on February 11th, 2014 | by Tina Casey


Friendly Mutant Algae Could Churn Out Sustainable Hydrogen On Your Desktop

February 11th, 2014 by  

The Jetsons could only dream about a gizmo like this: a desktop bioreactor swimming with microalgae that churn out hydrogen for your home fuel cell. For those of you who keep fish at home, the leap to a small scale  bioreactor doesn’t seem like that big of a deal, right?

As the hydrogen fuel cell market begins to rev up, you’re going to be hearing more about off-grid solutions for distributed, sustainable hydrogen generation. We’ve been following several photosynthesis based pathways using non-living materials (here and here, for example), and bacteria-based processes are also in the works (like here), but this algae thing is new on our radar.

sustainable hydrogen

Chlamydomonas reinhardti courtesy of DOE Joint Genome Institute.

A Microalgae Fuel Cell

The algae in question is a single celled green algae called Chlamydomonas reinhardtii. It is widely used as a research model due to its high degree of adaptability and fast reproductive cycle (that’s why we call it friendly, though apparently its official nickname is pronounced “Clammy”). Its main energy source is photosynthesis but it can also thrive on carbon in a dark environment.

According to the Carnegie Institute of Science, a sequencing of its 15,000 genes has revealed that it is “more plant than animal” (some critters that we call algae are actually bacteria), but it shares many genes that are either directly associated with human functions or are associated with key metabolic processes. According to one researcher on the project:

Although Chlamydomonas is certainly more plant than animal, there are clear similarities between this photosynthetic organism and animals that would surprise the average person on the street.

So, now that you have a bit of background on this intriguing critter, the hydrogen angle won’t surprise you.

Researchers at the National Renewable Energy Laboratory have been tinkering around with C. reinhardtii to see if they can get it to produce more hydrogen, and their latest results have just been published online at the Journal of Biological Chemistry under the title, “Identification of global ferredoxin interaction networks in Chlamydomonas reinhardtii.”

In a nutshell, here are the findings:

Scientists at the Energy Department’s National Renewable Energy Laboratory have demonstrated that just two of six iron-sulfur-containing ferredoxins in a representative species of algae promote electron transfers to and from hydrogenases.

That might not sound like such a big deal, but in terms of foundational research it is a giant step forward.

Ferredoxins are redox mediators containing iron and sulfur (redox mediator refers to electron transfer). They also happen to be one of the characteristics of C. reinhardtii with functions that have not yet been clearly determined.

By narrowing the field down from six to two ferredoxins, the NREL team has pushed forward the understanding of electron competition in C. reinhardtii. The idea moving forward would be to modify C. reinhardtii to force more electrons through the most productive pathways and block it from others.

That line of work is already promising, as NREL refers to previous studies showing that C. reinhardtii could be  genetically modified to outright eliminate certain pathways. That would steer more electrons to the cell’s hydrogenase, which is the enzyme that catalyzes the hydrogen reaction.

Sustainable Hydrogen

If you’re wondering why the hydrogen fuel cell market hasn’t exploded yet, one key reason is the enormous amount of conventional energy that it takes to manufacture hydrogen.

That could change in the near future. Although the new NREL research is a foundational project that won’t bear commercial fruit for a long time, sustainable hydrogen generation by microorganisms is coming into play.

Another federal lab, Lawrence Livermore National Laboratory, has been revving up a new wastewater-to-hydrogen demo project that extracts a hydrogen compound from decomposing solids using an energy efficient thermochemical process. If the process proves cost-effective, it could be deployed on a large scale at hundreds of municipal wastewater treatment plants around the country.

Similarly, a company called HyperSolar is already envisioning a network of hydrogen “farms”using nanoscale solar devices floating in waste feedstock including both municipal and industrial wastewater.

At the other end of the scale there’s a solar-powered toilet hitched up to a reactor that separates hydrogen gas from water and solids, which is currently being developed to help underserved communities improve their sanitary facilities.

Let’s also not forget the snail modded out to form a living fuel cell that could power small electronic devices, but for now we’re putting that in the category of sometime way in the future.

Another pathway is the aforementioned non-living materials, which basically means the development of photochemical cells that directly strip hydrogen from water using solar energy, without going through the mediator of electricity produced by a photovoltaic cell.

One promising example of this kind of sustainable hydrogen technology comes from Ecole Polytechnique Fédérale de Lausanne and Technion–Israel Institute of Technology, which have teamed up to create a photochemical cell based on an electrode made of nanostructured iron oxide (aka rust) particles.

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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+.

  • beernotwar

    If only there were a way to convert sunlight directly to electricity since we already have a complete system for moving electricity around, and trillions of devices designed to use it. Maybe that’s too snarky, but I think the challenges for hydrogen are great compared to the challenges of improving storage and solar cell efficiency. By the time the first hydrogen car goes into full scale production, there will be millions of battery-electric vehicles on the road and millions of chargers installed to service them. An entire hydrogen infrastructure will still have to be constructed to make the hydrogen car a practical alternative.

    • Bob_Wallace

      I agree. EVs are likely to set a very high bar for competitors.

      Electric motors are so very efficient. Electricity is cheap to produce. The distribution system is already in place.

      EVs will replace ICEVs mainly because they will be so much cheaper to operate. To replace EVs a new technology would have to be even cheaper and if it is necessary to build a brand new fueling infrastructure would be difficult.

      • Phil

        Obviously the advantage of such hydrogen production is simply that it’s far cheaper to produce a container with some algae and a hose coming out the top than it is to make a solar panel. Hydrogen can be stored in liquid form to be compact, and used to produce electricity with a Proton Exchange Membrane (PEM), Therefore your electric car only needs a tank for liquid hydrogen and a PEM (please look it up), this would then power your electric car with 0 emissions, pure H2o is the only waste product. You already have fuel stations that provide natural GAS (the literal word, not American word for ‘liquid’ petroleum gas- which is liquid so naming it gas is a bit stupid). They also provide LPG(liquid petroleum gas) which is a liquid form of a gas, just like liquid hydrogen would be provided. If you research hydrogen powered cars you would soon realise they do not ignite hydrogen, simply use it to produce electricity for electric cars.

        • Bob_Wallace

          I’m looking at the fourth word in the title – “Could”.
          The title does not say “Is Churning”.

          There’s two important things we don’t know: 1) can it be done? and 2) what would it cost if it can be done? Until those two questions are answered we aren’t going to get much further. But we can dream.

          I’ll dream along with you for a bit. Let’s assume we do figure out how to make H2 with algae. Would that make FCEVs a winner? How about we look at the graph below.

          First take a look at the right hand side of the figure. EVs, start with 100 kWh of energy and 67 kWh ends up as kinetic energy moving our car down the road.

          Now look at the left side, the H2 FCEV side. Start below electrolysis because algae’s doing that. There’s an energy loss when the H2 is compressed. An energy loss when the H2 is transported. And the fuel cell isn’t all that efficient at turning H2 into electricity, although I think they’re better than when this graph was made.

          Past the cost of algae H2, whatever that might be, there’s going to be a cost for electricity to do the compressing. There’s going to be a transportation cost. And there’s going to be some sort of energy loss in the fuel cell that is greater than the AC-DC/charging for the EV. It’s not like we have algae and then we drive away leaving mist in our wake.

          All those numbers have to be crunched. And all those losses have to be paid for.

          Would H2 from algae be a cheaper “fuel” than electricity? Can’t answer that.

          But wait! We failed to price in the cost of a H2 infrastructure. Were we to switch to H2 FCEVs we would have to build H2/algae plants on the scale we now have oil refineries. We’d have to have a fleet of H2 tankers to haul the stuff to fueling stations. We’d have to replace the ~125,000 fueling stations we have now for oil. The cost of all that would have to be added to the price of the hydrogen.

          Now, I’m not feeling like this is a really happy dream. It could turn into a H2 nightmare pretty quickly.

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