"Cheaper" and "more efficient" are the themes of greentech research announced this week.

Silicon sludge discarded while makingsolarwafers could make cars more efficient if researchers at Tokyo University of Science have their way.

Meanwhile, scientists at the Tokyo Institute of Technology presented technology aimed at applying the themes to solar-thermal, while Dartmouth College and Mascoma Corp. created a hungry bacterium that could do the same for cellulosic ethanol.

  • Researchers at the Tokyo University of Science have developed a process to produce electricity by reusing silicon discarded during the production of wafers. About 60 percent of the silicon becomes waste while making solar-cell and integrated-circuit wafers, according to a press release from research promotion site ResearchSea. Solar-cell production also creates silicon waste. The process developed by the Tokyo-based researchers turns silicon waste into magnesium silicide, which can trap thermal energy and convert it into electricity. The research could make use of the waste heat generated by automobiles' engines and exhausts.
  • A team of scientists at Dartmouth College and cellulosic-ethanol company Mascoma Corp. say they’ve genetically engineered a bacterium that could play an important role in finding cheaper and more effective ways to turn inedible plant material into biofuel. That’s because it can live at high temperatures and make pure ethanol without any detectable levels of messy byproducts, according to a report this week in the science journal Proceedings of the National Academy of Sciences of the Unites States of America (see the abstract here and a full PDF here).
  • The genetically altered bacteria, called Thermoanaerobacterium saccharolyticum, could be used to augment enzymes now used to make cellulosic ethanol, according to a Dartmouth news release. In the long term, the team’s discovery is only the first step in developing microbes that could make cellulosic ethanol without adding costly enzymes, said Lee Lynd, the Mascoma co-founder who led the research team, in the release.
  • Scientists at the Tokyo Institute of Technology claim they have developed new "beam-down" solar-thermal technologies that could greatly reduce the cost of solar-thermal systems. A "beam-down" system consists of a field of mirrors that track the sun and reflect sunlight to a large reflector, which in turn concentrates the sunlight to a receiver, which collects the heat that is then converted into electricity (see a diagram here). Researchers are developing new reflectors that have concentric circles supported by a triangular structure. According to a research paper, the shape and structure enable the reflectors to pick up light from a wider area and reflect it more efficiently, at a cost about half that of traditional reflectors.
  • The scientists also are developing intelligent tracking technology and receivers that use molten salt – instead of water or other liquids – to store the heat gathered by the systems. At a conference in Copenhagen last week, Tokyo Institute of Technology researchers said they plan to cut the cost of solar-power generation to 8 or 9 cents per kilowatt-hour, according to ResearchSea. The institute, along with Masdar and Cosmo Oil, are building a 100-kilowatt pilot plant in Abu Dhabi scheduled to open by June.