Berkeley Lab Researchers Use Solar Energy and Renewable Hydrogen to Produce Methane
A team of researchers at the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) developing a bioinorganic hybrid approach to artificial photosynthesis have achieved another milestone. Having generated quite a buzz with their hybrid system of semiconducting nanowires and bacteria that used electrons to synthesize carbon dioxide into acetate, the team has now developed a hybrid system that produces renewable molecular hydrogen and uses it to synthesize carbon dioxide into methane, the primary constituent of natural gas.
Artificial photosynthesis used to produce renewable molecular hydrogen for synthesizing carbon dioxide into methane
“This study represents another key breakthrough in solar-to-chemical energy conversion efficiency and artificial photosynthesis,” says Peidong Yang, a chemist with Berkeley Lab’s Materials Sciences Division and one of the leaders of this study. “By generating renewable hydrogen and feeding it to microbes for the production of methane, we can now expect an electrical-to-chemical efficiency of better than 50 percent and a solar-to-chemical energy conversion efficiency of 10-percent if our system is coupled with state-of-art solar panel and electrolyzer.”
Yang, who also holds appointments with UC Berkeley and the Kavli Energy NanoScience Institute (Kavli-ENSI) at Berkeley, is one of three corresponding authors of a paper describing this research in the Proceedings of the National Academy of Sciences (PNAS). The paper is titled “A hybrid bioinorganic approach to solar-to-chemical conversion.” The other corresponding authors are Michelle Chang and Christopher Chang. Both also hold joint appointments with Berkeley Lab and UC Berkeley. In addition, Chris Chang is a Howard Hughes Medical Institute (HHMI) investigator. (See below for a full list of the paper’s authors.)
Photosynthesis is the process by which nature harvests the energy in sunlight and uses it to synthesize carbohydrates from carbon dioxide and water. Carbohyrates are biomolecules that store the chemical energy used by living cells. In the original hybrid artificial photosynthesis system developed by the Berkeley Lab team, an array of silicon and titanium oxide nanowires collected solar energy and delivered electrons to microbes which used them to reduce carbon dioxide into a variety of value-added chemical products. In the new system, solar energy is used to split the water molecule into molecular oxygen and hydrogen. The hydrogen is then transported to microbes that use it to reduce carbon dioxide into one specific chemical product, methane.
“In our latest work, we’ve demonstrated two key advances,” says Chris Chang. “First, our use of renewable hydrogen for carbon dioxide fixation opens up the possibility of using hydrogen that comes from any sustainable energy source, including wind, hydrothermal and nuclear. Second, having demonstrated one promising organism for using renewable hydrogen, we can now, through synthetic biology, expand to other organisms and other value-added chemical products.”
The concept in the two studies is essentially the same - a membrane of semiconductor nanowires that can harness solar energy is populated with bacterium that can feed off this energy and use it to produce a targeted carbon-based chemical. In the new study, the membrane consisted of indium phosphide photocathodes and titanium dioxide photoanodes. Whereas in the first study, the team worked with Sporomusa ovata, an anaerobic bacterium that readily accepts electrons from the surrounding environment to reduce carbon dioxide, in the new study the team populated the membrane with Methanosarcina barkeri, an anaerobic archaeon that reduces carbon dioxide using hydrogen rather than electrons.
“Using hydrogen as the energy carrier rather than electrons makes for a much more efficient process as molecular hydrogen, through its chemical bonds, has a much higher density for storing and transporting energy,” says Michelle Chang.
In the newest membrane reported by the Berkeley team, solar energy is absorbed and used to generate hydrogen from water via the hydrogen evolution reaction (HER). The HER is catalyzed by
earth-abundant nickel sulfide nanoparticles that operate effectively under biologically compatible conditions. Hydrogen produced in the HER is directly utilized by the Methanosarcina barkeri archaeons in the membrane to produce methane.
“We selected methane as an initial target owing to the ease of product separation, the potential for integration into existing infrastructures for the delivery and use of natural gas, and the fact that direct conversion of carbon dioxide to methane with synthetic catalysts has proven to be a formidable challenge,” says Chris Chang. “Since we still get the majority of our methane from natural gas, a fossil fuel, often from fracking, the ability to generate methane from a renewable hydrogen source is another important advance.”
Adds Yang, “While we were inspired by the process of natural photosynthesis and continue to learn from it, by adding nanotechnology to help improve the efficiency of natural systems we are showing that sometimes we can do even better than nature.”
In addition to the corresponding authors, other co-authors of the PNAS paper describing this research were Eva Nichols, Joseph Gallagher, Chong Liu, Yude Su, Joaquin Resasco, Yi Yu and Yujie Sung.
This research was primarily funded by the DOE Office of Science.
# # #
Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.
Senior Writer, Media Coordinator
Mobile: 510 717-9625
Lynn Yarris | newswise
The role of Sodium for the Enhancement of Solar Cells
17.07.2018 | Max-Planck-Institut für Eisenforschung GmbH
Behavior-influencing policies are critical for mass market success of low carbon vehicles
17.07.2018 | International Institute for Applied Systems Analysis (IIASA)
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine