ScienceDaily (June 23, 2009) —
Scientists in Canada and India are proposing a surprising new solution to the global energy crisis —"milking" oil from the tiny, single-cell algae known as diatoms, renowned for their intricate, beautifully sculpted shells that resemble fine lacework.
Richard Gordon, T. V. Ramachandra, Durga Madhab Mahapatra, and Karthick Band note that some geologists believe that much of the world's crude oil originated in diatoms, which produce an oily substance in their bodies. Barely one-third of a strand of hair in diameter, diatoms flourish in enormous numbers in oceans and other water sources. They die, drift to the seafloor, and deposit their shells and oil into the sediments. Estimates suggest that live diatoms could make 10-200 times as much oil per acre of cultivated area compared to oil seeds, Gordon says.
"We propose ways of harvesting oil from diatoms, using biochemical engineering and also a new solar panel approach that utilizes genetically modifiable aspects of diatom biology, offering the prospect of "milking" diatoms for sustainable energy by altering them to actively secrete oil products," the scientists say. "Secretion by and milking of diatoms may provide a way around the puzzle of how to make algae that both grow quickly and have a very high oil content."
Journal reference:
1. Ramachandra et al. Milking Diatoms for Sustainable Energy: Biochemical Engineering versus Gasoline-Secreting Diatom Solar Panels. Industrial & Engineering Chemistry Research, 2009; 090609115002039 DOI: 10.1021/ie900044j
Tuesday, June 23, 2009
Tuesday, June 16, 2009
New US climate report dire, but offers hope
By SETH BORENSTEIN
WASHINGTON (AP) — Rising sea levels, sweltering temperatures, deeper droughts, and heavier downpours — global warming's serious effects are already here and getting worse, the Obama administration warned on Tuesday in the grimmest, most urgent language on climate change ever to come out of any White House.
But amid the warnings, scientists and government officials seemed to go out of their way to soften the message. It is still not too late to prevent some of the worst consequences, they said, by acting aggressively to reduce world emissions of heat-trapping gases, primarily carbon dioxide from the burning of fossil fuels.
The new report differs from a similar draft issued with little fanfare or context by George W. Bush's administration last year. It is paradoxically more dire about what's happening and more optimistic about what can be done.
The Obama administration is backing a bill in Congress that would limit heat-trapping pollution from power plants, refineries and factories. A key player on a climate bill in the Senate, California Democrat Barbara Boxer, said the report adds "urgency to the growing momentum in Congress" for passing a law.
"It's not too late to act," said Jane Lubchenco, one of several agency officials at a White House briefing. "Decisions made now will determine whether we get big changes or small ones." But what has happened already is not good, she said: "It's happening in our own backyards and it affects the kind of things people care about."
Lubchenco, a marine biologist, heads the National Oceanic and Atmospheric Administration.
In one of its key findings, the report warned: "Thresholds will be crossed, leading to large changes in climate and ecosystems." The survival of some species could be affected, it said.
The document, a climate status report required periodically by Congress, was a collaboration by about three dozen academic, government and institute scientists. It contains no new research, but it paints a fuller and darker picture of global warming in the United States than previous studies.
Bush was ultimately forced by a lawsuit to issue a draft report last year, and that document was the basis for this one. Obama science adviser John Holdren called the report nonpartisan, started by a Republican administration and finished by a Democratic one.
"The observed climate changes that we report are not opinions to be debated. They are facts to be dealt with," said one of the report's chief authors, Jerry Melillo of Marine Biological Lab in Woods Hole, Mass. "We can act now to avoid the worst impacts."
Among the things Melillo said he would like to avoid are more flooding disasters in New Orleans and an upheaval of the world's food supply.
The scientists softened the report from an earlier draft that said "tipping points have already been reached and have led to large changes." Melillo said that is because some of the changes seen so far are still reversible.
Even so, Tom Karl of the National Climatic Data Center said that at least one tipping point — irreversible sea level rise — has been passed.
A point of emphasis of the report, which is just under 200 pages, is what has already happened in the United States. That includes rapidly retreating glaciers in the American West and Alaska, altered stream flows, trouble with the water supply, health problems, changes in agriculture, and energy and transportation worries.
"There are in some cases already serious consequences," report co-author Anthony Janetos of the University of Maryland told The Associated Press. "This is not a theoretical thing that will happen 50 years from now. Things are happening now."
For example, winters in parts of the Midwest have warmed by 7 degrees in just 30 years and the frost-free period has grown a week, the report said.
Shorter winters have some benefits, such as longer growing seasons, but those are changes that require adjustments just the same, the authors note.
The "major disruptions" already taking place will only increase as warming continues, the authors wrote. The world's average temperature may rise by as much as 11.5 degrees by the end of the century, the report said. And the U.S. average temperature could go even higher than that, Karl said.
Environmental groups praised the report as a call for action, with the Union of Concerned Scientists calling it what "America needs to effectively respond to climate change."
Scott Segal, a Washington lobbyist for the coal industry, was more cautious: "Fast action without sufficient planning is a route to potential economic catastrophe with little environmental gain."
Associated Press Writer Dina Cappiello in Washington contributed to this report.
Wednesday, June 10, 2009
Roll-Up Solar Panels
Technology Review Thursday, June 04, 2009
A startup is making thin-film solar cells on flexible steel sheets.
By Prachi Patel
Xunlight, a startup in Toledo, Ohio, has developed a way to make large, flexible solar panels. It has developed a roll-to-roll manufacturing technique that forms thin-film amorphous silicon solar cells on thin sheets of stainless steel. Each solar module is about one meter wide and five and a half meters long.
As opposed to conventional silicon solar panels, which are bulky and rigid, these lightweight, flexible sheets could easily be integrated into roofs and building facades or on vehicles. Such systems could be more attractive than conventional solar panels and be incorporated more easily into irregular roof designs. They could also be rolled up and carried in a backpack, says the company's cofounder and president, Xunming Deng. "You could take it with you and charge your laptop battery," he says.
Amorphous silicon thin-film solar cells can be cheaper than conventional crystalline cells because they use a fraction of the material: the cells are 1 micrometer thick, as opposed to the 150-to-200-micrometer-thick silicon layers in crystalline solar cells. But they're also notoriously inefficient. To boost their efficiency, Xunlight made triple-junction cells, which use three different materials--amorphous silicon, amorphous silicon germanium, and nanocrystalline silicon--each of which is tuned to capture the energy in different parts of the solar spectrum. (Conventional solar cells use one primary material, which only captures one part of the spectrum efficiently.)
Still, Xunlight's flexible PV modules are only about 8 percent efficient, while some crystalline silicon modules on the market are more than 20 percent efficient. As a result, Xunlight's large modules produce only 330 watts, whereas an array of crystalline silicon solar panels covering the same area would produce about 740 watts.
United Solar Ovonic, based in Auburn Hills, MI, is already selling flexible PV modules. The company also uses triple-junction amorphous silicon cells, and its modules can be attached to roofing materials. But Xunlight's potential advantage is its high-volume roll-to-roll technique. "If their roll-to-roll process allows them to go to lower cost and larger area, that's the central advantage," says Johanna Schmidtke, an analyst with Lux Research, in Boston. "But they have to prove it with manufacturing."
Other companies, notably Heliovolt and Nanosolar, are in a race to make thin-film panels using copper indium gallium selenide (CIGS) cells. These have shown efficiencies on par with crystalline silicon and can be made on flexible substrates. In comparison with amorphous silicon, CIGS is a relatively difficult material to work with, and no one has been able to create low-cost products consistently in large quantities, says Ryan Boas, an analyst with Photon Consulting, in Boston.
Building integrated photovoltaics (BIPV), especially rooftop applications, would be the biggest market for flexible PV technology, Boas says. That's because flexible products are inherently very light, in addition to being quick and easy to install. "Imagine carrying a roll of flexible product on the roof and unrolling it," he says. "Workers are already used to unrolling roofing material."
But there are hidden risks and costs associated with BIPV, Schmidtke says. "BIPV is often touted as low cost," she says, "but in actuality, you've got greater risk in terms of a watertight system [for roofing materials] or fire risk, and that increases total installation cost." However, BIPV does have the advantage of being more aesthetically pleasing, which is important to consumers, she says.
So far, Xunlight has raised $40 million from investors. In December, the state of Ohio gave the company a $7 million loan to speed up the construction of a 25-megawatt production line for its flexible solar modules. The company expects to have commercial products available in 2010.
Copyright Technology Review 2009.
A startup is making thin-film solar cells on flexible steel sheets.
By Prachi Patel
Xunlight, a startup in Toledo, Ohio, has developed a way to make large, flexible solar panels. It has developed a roll-to-roll manufacturing technique that forms thin-film amorphous silicon solar cells on thin sheets of stainless steel. Each solar module is about one meter wide and five and a half meters long.
As opposed to conventional silicon solar panels, which are bulky and rigid, these lightweight, flexible sheets could easily be integrated into roofs and building facades or on vehicles. Such systems could be more attractive than conventional solar panels and be incorporated more easily into irregular roof designs. They could also be rolled up and carried in a backpack, says the company's cofounder and president, Xunming Deng. "You could take it with you and charge your laptop battery," he says.
Amorphous silicon thin-film solar cells can be cheaper than conventional crystalline cells because they use a fraction of the material: the cells are 1 micrometer thick, as opposed to the 150-to-200-micrometer-thick silicon layers in crystalline solar cells. But they're also notoriously inefficient. To boost their efficiency, Xunlight made triple-junction cells, which use three different materials--amorphous silicon, amorphous silicon germanium, and nanocrystalline silicon--each of which is tuned to capture the energy in different parts of the solar spectrum. (Conventional solar cells use one primary material, which only captures one part of the spectrum efficiently.)
Still, Xunlight's flexible PV modules are only about 8 percent efficient, while some crystalline silicon modules on the market are more than 20 percent efficient. As a result, Xunlight's large modules produce only 330 watts, whereas an array of crystalline silicon solar panels covering the same area would produce about 740 watts.
United Solar Ovonic, based in Auburn Hills, MI, is already selling flexible PV modules. The company also uses triple-junction amorphous silicon cells, and its modules can be attached to roofing materials. But Xunlight's potential advantage is its high-volume roll-to-roll technique. "If their roll-to-roll process allows them to go to lower cost and larger area, that's the central advantage," says Johanna Schmidtke, an analyst with Lux Research, in Boston. "But they have to prove it with manufacturing."
Other companies, notably Heliovolt and Nanosolar, are in a race to make thin-film panels using copper indium gallium selenide (CIGS) cells. These have shown efficiencies on par with crystalline silicon and can be made on flexible substrates. In comparison with amorphous silicon, CIGS is a relatively difficult material to work with, and no one has been able to create low-cost products consistently in large quantities, says Ryan Boas, an analyst with Photon Consulting, in Boston.
Building integrated photovoltaics (BIPV), especially rooftop applications, would be the biggest market for flexible PV technology, Boas says. That's because flexible products are inherently very light, in addition to being quick and easy to install. "Imagine carrying a roll of flexible product on the roof and unrolling it," he says. "Workers are already used to unrolling roofing material."
But there are hidden risks and costs associated with BIPV, Schmidtke says. "BIPV is often touted as low cost," she says, "but in actuality, you've got greater risk in terms of a watertight system [for roofing materials] or fire risk, and that increases total installation cost." However, BIPV does have the advantage of being more aesthetically pleasing, which is important to consumers, she says.
So far, Xunlight has raised $40 million from investors. In December, the state of Ohio gave the company a $7 million loan to speed up the construction of a 25-megawatt production line for its flexible solar modules. The company expects to have commercial products available in 2010.
Copyright Technology Review 2009.
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