1. Bio-solar cells
For the first time ever, researchers connected nine biological-solar (bio-solar) cells into a bio-solar panel and continuously produced electricity from the panel and generated the most wattage of any existing small-scale bio-solar cells.
Last year, the group took steps towards building a better bio-solar cell by changing the materials used in anodes and cathodes (positive and negative terminals) of the cell and also created a miniature microfluidic-based single-chambered device to house the bacteria instead of the conventional, dual-chambered bio-solar cells.
However, this time, the group connected nine identical bio-solar cells in a 3x3 pattern to make a scalable and stackable bio-solar panel. The panel continuously generated electricity from photosynthesis and respiratory activities of the bacteria in 12-hour day-night cycles over 60 total hours.
The current research is the latest step in using cyanobacteria—which can be found in almost every terrestrial and aquatic habitat on earth—as a source of clean and sustainable energy.
Even with the breakthrough, a typical “traditional” solar panel on the roof of a residential house, made up of 60 cells in a 6x10 configuration, generates roughly 200 watts of electrical power at a given moment. The cells from this study, in a similar configuration, would generate about 0.00003726 watts. So, it isn’t efficient just yet, but the findings open the door to future research of the bacteria itself.
“Once a functional bio-solar panel becomes available, it could become a permanent power source for supplying long-term power for small, wireless telemetry systems as well as wireless sensors used at remote sites where frequent battery replacement is impractical,” said Seokheun ‘Sean’ Choi, an assistant professor of electrical and computer engineering in Binghamton University’s Thomas J. Watson School of Engineering and Applied Science, and co-author of the paper, in a 11 April press statement.
The findings are currently available online and will be published in the June edition of the journal Sensors and Actuators B: Chemical.
2. A new way for converting solar energy into electricity
Researchers from The Hebrew University of Jerusalem in Israel, and the University of Bochum in Germany, reported a new paradigm for the development of photo-bioelectrochemical cells in Nature Energy this January, providing a means for the conversion of solar energy into electricity.
While photosynthesis is the process by which plants and other organisms make their own food using carbon dioxide, water and sunlight, bioelectrochemical systems take advantage of biological capacities (microbes, enzymes, plants) for the catalysis of electrochemical reactions.
In a 19 January press statement, the researchers pointed out that although significant progress has been achieved in the integration of native photosystems with electrodes for light-to-electrical energy conversion, uniting photosystems with enzymes to yield photo-bioelectrocatalytic solar cells remains a challenge.
Hence, the researchers constructed photo-bioelectrochemical cells using the native photosynthetic reaction and the enzymes glucose oxidase, or glucose dehydrogenase. The system comprises modified integrated electrodes that include the natural photosynthetic reaction centre, known as photosystem I, along with the enzymes. The native proteins are electrically wired by means of chemical electron transfer mediators. Photo-irradiation of the electrodes leads to the generation of electrical power, while oxidizing the glucose substrate acts as a fuel.
The system provides a model to harness the native photosynthetic apparatus for the conversion of solar light energy into electrical power, using biomass substrates as fuels. Itamar Willner, a professor at the Hebrew University’s Institute of Chemistry, said in a statement: “The study results provide a general approach to assemble photo-bioelectrochemical solar cells with wide implications for solar energy conversion, bioelectrocatalysis and sensing.”
3. Reshaping solar spectrum to turn light into electricity
Land and labour costs account for the bulk of the expense when installing solar panels since solar cells—made often of silicon or cadmium telluride—rarely account for more than 20% of the total cost. Hence, solar energy could be made cheaper if less land had to be purchased to accommodate the panels. This is best achieved if each solar cell generates more power, but it is not easy.
A team of chemists at the University of California says it has found a way to make this happen. In a paper that was published in Nano Letters, an American Chemical Society publication, the researchers said that by combining inorganic semiconductor nanocrystals with organic molecules, they succeeded in “upconverting” (two low-energy photons into one high-energy photon) photons in the visible and near-infrared regions of the solar spectrum.
The infrared region of the solar spectrum passes right through the photovoltaic materials that make up today’s solar cells, explained Christopher Bardeen, a professor of chemistry in a press release on 27 July 2015. This upconverted photon is readily absorbed by photovoltaic cells, generating electricity from light that normally would be wasted, according to Bardeen.
He added that these materials are essentially “reshaping the solar spectrum” so that it better matches the photovoltaic materials used today in solar cells. The ability to utilize the infrared portion of the solar spectrum could boost solar photovoltaic efficiencies by 30% or more.
Besides solar energy, the ability to upconvert two low-energy photons into one high-energy photon has potential applications in biological imaging, data storage and organic light-emitting diodes, says Bardeen.