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Synthetic trees to purify air
A SCIENTIST has invented an artificial tree designed to do the job of plants. But the synthetic tree proposed by Dr Klaus Lackner does not much resemble the leafy variety.
“It looks like a goal post with Venetian blinds,” said the Columbia University physicist, referring to his sketch at the annual AAAS meeting in Denver, Colorado.
However, the synthetic tree would do the job of a real tree, he said. It would draw carbondioxide out of the air, as plants do during photosynthesis, but retain the carbon and not release oxygen.
If done to scale, according to Dr Lackner, synthetic trees could help clean up an atmosphere grown heavy with carbon dioxide, the most abundant gas produced by humans and implicated in climate warming.
He predicts that one synthetic tree could remove 90,000 tonnes of CO2 in a year, the emissions equivalent of 15,000 cars.
“You can be a thousand times better than a living tree,” he said.
For now, the synthetic tree is still a paper idea. But Dr Lackner is serious about developing a working model. His efforts suggest the wide net of ideas cast by scientists as they face the challenge of mitigating climate change.
Dr Lackner believes that carbon sequestration technology must be part of the long-term solution. Global reliance on fossil fuels will not decrease any time soon, he said, and developing countries cannot be expected to wait until alternatives are available.
The technology calls for two things - seizing carbon and then storing it. Direct capture of CO2, from power plants for example, is the simplest, according to Dr Lackner. But this doesn’t work for all polluters. A car can’t capture and store its carbon dioxide on-board; the storage tank would be too large.
“It’s simply a question of weight,” he said, “for every 14 grams of gasoline you use, you are going to have 44 grams of CO2.”
The alternative is to capture emissions from the wind. In this case, a synthetic tree would act like a filter. An absorbent coating, such as limewater, on its slats or “leaves” would seize carbon dioxide and retain the carbon.
Dr Lackner predicts that the biggest expense would be in recycling the absorber material.
Dr Lackner is considering other less-alkaline solutions to prevent carbonate precipitation.
A synthetic tree could be planted anywhere. A small one could sit like a TV on the lawn to balance out the CO2 emitted by one person or family.
But more practically, said Dr Lackner, a device the size of a barn would sit in the open air, near repositories for easy transportation and storage of carbon.
He estimated that 250,000 synthetic trees worldwide would be needed to soak up the 22 billion tons of CO2 produced annually.
But not everyone is rooted to the idea. Massachusetts Institute of Technology engineer Howard Herzog thinks Dr Lackner’s design won’t hold together on the scale he proposes.
He said you would expend more energy in capturing the CO2 — in keeping the slats coated in absorbent and disposing of it — than you’d save. He said that much more research is needed on the technology.
But Dr Lackner is optimistic that the costs for carbon capture and storage will come down.
Fifth closest star discovered
Astronomers have discovered one of the closest stars to our Sun, and they say that more undetected close neighbours may be lurking in our vicinity.
The new star was found because its relatively swift motion across the sky was picked up by automated sky surveys.
It ranks as the third closest star system and the fifth closest star to our Sun.
It is a faint red star, a so-called red dwarf, and is only 7.5 light years away.
As yet unnamed the new star goes by the designation SO025300.5+165258.
It is the closest star system to us after the Alpha Centauri system and Barnard’s star.
The discovery was made by searching databases of star images recorded by automated sky surveys.
Such surveys are undertaken to look for comets and asteroids as well as exploding stars.
Because they are regular snapshots of regions of the sky they are also useful for finding nearby stars.
Nearby stars betray their presence through having a large “proper motion” — that is their natural motion through space, although no greater than most stars, is more pronounced because of their closeness.
When the new star was detected it was subsequently found in photographs going back half a century.
It is a small dim red dwarf star, nothing unusual in cosmic terms, one of the common folk of the galaxy.
But measurements do indicate that it is one of the closest ever found to our Sun.
The researchers who found it, an international team led by Bonnard Teegarden of the American space agency (Nasa), say that other nearby stars are surely waiting to be discovered.
Gravity wave detector all set
The hunt is well and truly joined. Scientists report here that one of the greatest observatories ever constructed works as expected and is now ready to go for goal.
The Ligo (Laser Interferometer Gravitational Wave Observatory) facility, built at a cost of nearly $300m, is trying to detect gravity waves, the ripples created in the fabric of space-time that occur every time a star explodes or black holes collide. If it succeeds, scientists will not only confirm cherished theories, they will also have a new window on the Universe that will enable them to probe the nature of the cosmos right back to the beginning of time itself.
Researchers connected with the project said initial experiments showed Ligo could achieve the extraordinary sensitivities required to pick up the waves. The researchers also reported they would be putting in a request for $150m of further funding to boost the power of the facility. — Dawn ScienceDotcom Report
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