A New Type of Solar Cell

Scientists in Japan have made the first device that can convert solar energy into electricity and then store the resulting electric charge. The "photocapacitor" designed by Tsutomu Miyasaka and Takurou Murakami at Toin University in Yokohama could be used to power mobile phones and other hand-held devices (Appl. Phys. Lett. 85 3932).

Conventional solar cells need a secondary device, such as a battery, to store the electrical power generated from light. The photocapacitor combines the photoelectric and storage functions in a single structure.

Miyasaka says that the next goal is to increase the charging voltage and the charge-discharge capacity to a practically and industrially useful level for applications.

Link PhysicsWeb – News – A new type of solar cell (November 2004).

via http://www.worldchanging.com/archives/001529.html

Alternative Energy Megaprojects

Two projects described at WorldChanging:

The first is the new "tidal lagoon" power system under construction at the mouth of the Yalu River in China. British company Tidal Electric is the lead engineering group on the project. At 300 MW, it will be the largest tidal power project in the world. Tidal lagoon power systems use large-scale enclosures which generate power as they are filled or emptied by the change in tides. Lagoon systems present less of a disruption to the local ecosystem than the "barrage" generators more often used in tidal power systems (such as the current largest tidal power generator, the Rance River project in Brittany, France). Although tidal power is not available at a constant rate, it is predictable, making it easy to integrate into existing power grids. Despite the size of this project, it looks like a winner.

As ambitious as tidal lagoons may be, they pale in comparison to the Solar Thermal Tower scheduled for construction in Australia. At a kilometer in height, with a base collector five kilometers across, the tower would be potentially the largest construction project ever. The principle is simple: air beneath the collection area is heated by the sun, much as in a greenhouse, and rises up the tower, where the differential in pressure between the top and the bottom keeps the air moving fast enough to drive turbines — in essence, it’s a heat-pumped super-windmill system. The tower is supposed generate 200 MW, and should be able to do so fairly constantly, even at night. A test tower built in Spain in the late 80s demonstrated that the technology works, albeit on a much smaller scale. The Solar Tower has been approved by the Australian government, and construction is intended to begin next year (a 2002 New Scientist article about the idea suggested that work was supposed to begin in 2003, so this may be one of those perpetually-a-year-away endeavors).

There are still many questions about the feasibility of the Solar Tower, ranging from keeping it stable in the winds at 1 km to whether a heat-trapping project of that size would alter the regional environment. There’s also the question of cost — can it be built inexpensively enough to make the power generated competitive with more conventional approaches?

Link WorldChanging: Another World Is Here: Alternative Energy Megaprojects.

Picture of Bushtit

Bushtit Psaltriparus minumus


Identification Tips: Bushtit

  • Length: 3.5 inches
  • Short bill
  • Pale gray upperparts
  • Whitish underparts
  • Long gray tail
  • Sexes similar
  • Some variation in plumage-coastal birds have brownish crowns, interior birds have brownish cheeks, some birds from near Mexico have black cheeks
  • Usually found in flocks

Interface Has Recycled 60 Million Pounds of Carpet

ATLANTA, Ga., Oct. 28, 2004 – It’s been ten years since Interface founder Ray Anderson first introduced his company’s journey to sustainability — an early vision that appears to be paying off. The company recently announced that nearly 60 million pounds of carpet has been reclaimed since 1995 through ReEntry, its aggressive carpet-reclamation program.

"Rather than abandon over 30 years and 250 million pounds of vinyl backing already in the marketplace, Interface has made a commitment to recycle carpet backing," said John Wells, president of Interface Flooring Systems. "Year after year growth of our ReEntry program validates that carpet recycling is not only the right thing to do, but something that the marketplace is demanding as well. It is good business."

ReEntry tracks carpet collected from sites across the U.S. As of June 2004, the program has reclaimed 57 million pounds of carpet, of which: 52% has been recycled as GlasBacoRE, the Interface recycled vinyl backing system. Of the carpet that has been recycled. 40% has been used for energy capture and conversion, or converted from waste to energy. While not as preferable as pure recycling, this process keeps the product out of the landfill. Eight percent has been repurposed, having been removed before the end of its useful life, carpet is donated to a nonprofit organization.

Addressing concerns about vinyl, Wells stresses that Interface has made a commitment to exit all virgin petro-chemically derived materials in its processes. "Science shows us that when vinyl is used as intended, it has no negative health effects," explains Wells. "Reclaiming it helps us begin to close the loop and acknowledges that there is a bounty of vinyl-backed carpet out there for which someone must take responsibility. Interface has committed to exit all virgin petro-chemically derived materials (not just vinyl). Any material that relies on virgin petrochemicals has an inherently negative impact on the environment."

Link GreenBiz News | Interface Celebrates Nearly 60 Million Pounds of Reclaimed Carpet