Solar

[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]

Report from CS3 Symposium Highlights Work Toward Artificial Photosynthesis For Direct Solar Production of Liquid Transportation Fuels

November 06, 2009

Scientists are making progress toward development of an “artificial leaf” that mimics photosynthesis, but that converts sunlight and water into a liquid fuel such as methanol for cars and trucks, according to a new report summarizing the discussions from the 1^st Annual Chemical Sciences and Society Symposium (CS3). However, much work remains to be done in all the component areas, as well as in the integration of the components to a viable artificial leaf.

The three-day symposium, which took place in Germany this past summer, included 30 chemists from China, Germany, Japan, the United Kingdom and the United States. It was organized through a joint effort of the science and technology funding agencies and chemical societies of each country, including the US National Science Foundation and the American Chemical Society (ACS).

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Consortium Wins $2.2M ARPA-E Award for Direct Solar Bio-Hydrocarbon Fuel Research; Biocatalytic Coatings Using Bacteria Embedded in Latex

October 30, 2009

A consortium comprising researchers from the University of Minnesota and the Pacific Northwest National Laboratory, with BioCee, a University of Minnesota start-up company as the commercialization partner, has been awarded $2.2 million from the Department of Energy’s ARPA-E program for a research proposal to use bacteria to produce bio-hydrocarbon fuels from CO₂ and sunlight. (Earlier post.)

The consortium proposes to use an innovative artificial symbiotic colony of photosynthetic bacteria with Shewanella, a hydrocarbon-producing bacteria. The photosynthetic organisms will use sunlight to convert CO₂ to sugar, which the Shewanella will then convert to bio-hydrocarbons. The bioreactor will use biocatalytic coatings—bacteria embedded in a thin latex coating.

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GWU Researcher Developing Efficient Solar Chemical Process for Generation of Energetic Molecules and Conversion of CO2

September 05, 2009

(Left) Charge and heat flow in the STEP system. Colored arrows indicate the direction of heat flow (yellow arrows), electron flow (blue), and reagent flow (green). (Right) Auxiliary components to reach higher STEP temperatures and/or decrease the heat incident on the PV. Light harvesting can use various optical concentrators and beam splitters can redirect sub-bandgap radiation away from the PV onto the electrolyzer. Licht, 2009. Click to enlarge.

Dr. Stuart Licht (earlier post) at George Washington University is developing a solar-driven process that, he says, could efficiently replace current industrial processes for the production of certain energetic molecules such as hydrogen, metals and chlorine, which are responsible for a large component of anthropogenic CO₂. It can also convert captured anthropogenic CO₂, generated by burning fossil fuels, to CO and O₂ via high-temperature electrolysis. A paper on his work is in press for the ACS’ Journal of Physical Chemistry, C.

One third of the global industrial sector’s annual emission of 1x10¹⁰ metric tons of CO₂ is released in the production of metals and chlorine. This, together with the additional CO₂ from electrical generation, heating and transportation, comprise the majority of CO₂ emissions.

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New Three-Component Catalyst Efficiently Produces Hydrogen From Sun and Aqueous Solutions with Sulfur

August 17, 2009

An artificial photocatalyst can achieve quantum efficiency up to 93% in photocatalytic H2 production from Na2S–Na2SO3 aqueous solution under visible light irradiation. Yan et al. Click to enlarge.

Researchers at the Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences have developed a new three-component photocatalyst that produces hydrogen with a quantum efficiency (QE) of up to 93% in the presence of sacrificial reagents under visible light irradiation, and is very stable under the photocatalytic reaction conditions.

The catalyst—cadmium sulfide doped with palladium sulfide and platinum (Pt–PdS/Cd)—can achieve its extremely high QE with loadings as low as 0.30 wt% of Pt and 0.13 wt% of PdS as co-catalysts on CdS. Quantum efficiency can be expressed as the number of product molecules to incident photons.

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Mitsubishi and Partners Develop Highly Integrated Organic Photovoltaics Module

June 21, 2009

Structure of the OPV. Source: Mitsubishi Corporation. Click to enlarge.

Mitsubishi Cooperation (MC), the National Institute of Advanced Industrial Science and Technology (AIST) and Tokki Corporation have developed a new, highly-integrated Organic Photovoltaics (OPV) module.

Like silicone PVs, OPVs employ a P-N diode junction as a generating active layer. The biggest challenge over some 30 plus years of R&D has been raising the low power output of PVs. In January, 2005, AIST achieved 4.0% light exchange efficiency with the introduction of a bulk-hetero junction (i-layer). At the time, this was the highest efficiency rate that had ever been achieved.

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Researchers Propose Solar-Driven Biomass Gasification Pathway for Synthetic Fuel Production

May 01, 2009

Schema of synfuel synthesis through solar-driven biomass gasification. Solar energy produces both heat for gasification and H2 via electrolysis. From Hertwich et al. (2009) Click to enlarge.

Researchers at the Norwegian University of Science and Technology (NTNU) are proposing a new process for producing synfuel from biomass using concentrating solar energy as its main energy source.

High temperature heat for biomass gasification is obtained from a molten-salt system in a solar concentrating tower. Hydrogen for reverse water gas shift reaction to avoid producing CO₂ during the process is produced by electrolyzing water, driven by solar power.

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New Nano-sized Photocatalyst for Artificial Photosynthesis; Step Toward Production of Carbon-Neutral Transportation Fuels

March 13, 2009

Under the fuel through artificial photosynthesis scenario, nanotubes embedded within a membrane would act like green leaves, using incident solar radiation (Hν) to split water molecules (H2O), freeing up electrons and oxygen (O2) that then react with carbon dioxide (CO2) to produce a fuel, shown here as methanol (CH3OH). Credit: Flavio Robles, Berkeley Lab Public Affairs. Click to enlarge.

Artificial photosynthesis for the production of liquid fuels is a potential source for renewable and carbon-neutral of transportation energy. The basic concept is to integrate light-harvesting systems that can capture solar photons and catalytic systems that can oxidize water, then to combine this water oxidation half reaction with a carbon dioxide reduction step in an artificial-leaf type system to produce a liquid hydrocarbon, such as methanol (CH₃OH), that can be stored, transported, and used for transportation or other applications.

Researchers with the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have now found that nano-sized crystals of cobalt oxide can effectively carry out the critical photosynthetic reaction of splitting water molecules. Heinz Frei, a chemist with Berkeley Lab’s Physical Biosciences Division, and his postdoctoral fellow Feng Jiao reported the results of their study in the journal Angewandte Chemie, in a paper entitled: “Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen-Evolving Catalysts.”

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Researchers Develop Method for Higher-Rate Solar Photocatalytic Conversion of CO2 and Water Vapor to Hydrocarbon Fuels

January 28, 2009

Product generation rates from a nitrogen-doped nanotube array film surface-loaded with both Pt and Cu catalysts. Credit: ACS. Click to enlarge.

Researchers at Penn State have developed a method for the more efficient solar conversion of carbon dioxide and water vapor to methane and other hydrocarbons using nitrogen-doped titania nanotube arrays. The arrays feature a wall thickness low enough to facilitate effective carrier transfer to the adsorbing species, and are surface-loaded with nanodimensional islands of co-catalysts platinum (Pt) and/or copper (Cu).

A paper on their work was published online 27 January in the ACS journal Nano Letters.

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