Mechanical 'fish' could tap turbulence for energy

Devices that harvest energy from swirling wakes surrounding buildings are being developed by US researchers. Their novel designs – inspired by fish – could generate electricity using eddies, something that conventional turbines cannot do.

Fish use their bodies to get an energy boost from surrounding vortices, which may be created by other fish in the same shoal, or by stationary objects in the water. But this kind of turbulent flow cannot be used by conventional wind or water turbines, which instead need a steady flow.

John Dabiri at the California Institute of Technology, Pasadena, US, realised that it might be possible for a mechanical system to extract energy from vortex wakes and has developed a mathematical model, based on the way fish move, to help put this into practice.

"In fish we have a working example of a system that extracts energy from vortices, now we need to work out how to build our own," he says.

Lateral drift

Fish move from side to side in order to exploit the way wakes in flowing water produce vortices that alternately spin clockwise and anticlockwise, as shown in the videos on this page.

For a mechanical device to pick up energy from an eddy, Dabiri's model shows that it must also change its angle in a similar way to a fish, to pick up as much energy as possible.

"We need a device that can be aware of what is happening upstream and position itself relative to incoming flows accordingly," says Dabiri.

"To exploit this we [also] need to find locations with naturally occurring fluctuations," says Dabiri. "This is exactly the situation in urban environments." Buildings constantly produce turbulent wakes making many rooftops unsuitable for normal wind turbines, but perfect for harvesting eddies.

Dabiri and colleagues have begun designing prototypes devices for use in the air and in the water. "They look less like a fish than you might think – we aren't trying to copy them directly, just to uncover and use the underlying dynamics of what they do."

Slow but steady

Once operational such devices will generate less power than a normal wind turbine in full flow, but should still compete over the long term, Dabiri says. "Turbines need wind to get over about 10 metres per second to work," he says. "But we should be able to extract energy all the time. It's like the tortoise and the hare." Over about a year, Dabiri says, the two may harness the same total energy.

James Liao a biologist at Cornell University, US, first demonstrated in 2003 that fish in shoals use vortices to save energy, something long suspected.

Liao says Dabiri's model will help to push the concept forward. "It could make this idea accessible to a wider audience," he says. Dabiri's model is a simplified version, he adds, but a full model of the fluid dynamics involved is impractical, because of the complexity of modelling both a wake and the effect of a moving fish.

Laio has previously collaborated with other engineers interested in harvesting energy from vortices and is now looking at how fish use their lateral lines to sense vortices and guide the way they move. "The question is, what do you need from the environment to be able to do this," he says. "That is also important for any man-made uses of vortices."

Journal reference: Bioinspiration & Biomimetics (DOI: 10.1088/1748-3182/2/3/L01)

Energy and Fuels - Learn more about the looming energy crisis in our comprehensive special report.

Go nuclear for a third industrial revolution, says EC

We are on the brink of the "third industrial revolution", according to José Manuel Barroso, president of the European Commission - who believes it means nations may have to embrace nuclear power.

Europe's "low-carbon age" is the revolution Barroso spoke of last week at an energy conference in Madrid, Spain. "Member states cannot avoid the question of nuclear energy," he said, following the commission's announcement last month of a new research initiative for nuclear energy. The European Union should contribute to research, Barroso said.

However, not all of Europe shares his view. At a separate nuclear energy conference in Vienna last week, environment ministers from Austria, Germany, Ireland, Latvia, Norway and Italy declared that global growth in nuclear power would severely increase the risks of nuclear proliferation. "Some European countries are almost religiously opposed to nuclear power," says Hans-Holger Rogner of the International Atomic Energy Agency in Vienna.

From issue 2625 of New Scientist magazin

Gore's climate film has scientific errors - judge

· Court rules documentary can be shown in schools · Presentation is 'broadly accurate' but lacks balance
David Adam, environment correspondent
The Guardian
Thursday October 11 2007
Al Gore's Oscar-winning documentary on global warming, An Inconvenient Truth, was yesterday criticised by a high court judge who highlighted what he said were "nine scientific errors" in the film.
Mr Justice Barton yesterday said that while the film was "broadly accurate" in its presentation of climate change, he identified nine significant errors in the film, some of which, he said, had arisen in "the context of alarmism and exaggeration" to support the former US vice-president's views on climate change.
The film was broadly welcomed by environmental campaigners and scientists on its release last year, and while they did point out that it contained mistakes, these were relatively small and did not detract from the film's central message - that global warming was a real problem and humans had the technology to do something about it.
The judge made his remarks when assessing a case brought by Stewart Dimmock, a Kent school governor and a member of a political group, the New party, who is opposed to a government plan to show the film in secondary schools.
The judge ruled that the film can still be shown in schools, as part of a climate change resources pack, but only if it is accompanied by fresh guidance notes to balance Mr Gore's "one-sided" views. The "apocalyptic vision" presented in the film was not an impartial analysis of the science of climate change, he said.
The judge also said it might be necessary for the Department of Children, Schools and Families to make clear to teachers some of Mr Gore's views were not supported or promoted by the government, and there was "a view to the contrary".
He said he had viewed the film and described it as "powerful, dramatically presented and highly professionally produced", built around the "charismatic presence" of Mr Gore, "whose crusade it now is to persuade the world of the dangers of climate change".
The mistakes identified mainly deal with the predicted impacts of climate change, and include Mr Gore's claims that a sea-level rise of up to 20ft would be caused by melting in either west Antarctica or Greenland "in the near future".
The judge said: "This is distinctly alarmist and part of Mr Gore's 'wake-up call'." He accepted that melting of the ice would release this amount of water - "but only after, and over, millennia."
Despite his finding of significant errors, Mr Justice Barton said many of the claims made by the film were supported by the weight of scientific evidence and he identified four main hypotheses, each of which is very well supported "by research published in respected, peer-reviewed journals and accords with the latest conclusions of the IPCC [Intergovernmental Panel on Climate Change]."
The nine points: fact or fallacy?
· The film claimed that low-lying inhabited Pacific atolls "are being inundated because of anthropogenic global warming" - but there was no evidence of any evacuation occurring
· It spoke of global warming "shutting down the ocean conveyor" - the process by which the gulf stream is carried over the north Atlantic to western Europe. The judge said that, according to the Intergovernmental Panel on Climate Change, it was "very unlikely" that the conveyor would shut down in the future, though it might slow down
· Mr Gore had also claimed - by ridiculing the opposite view - that two graphs, one plotting a rise in C02 and the other the rise in temperature over a period of 650,000 years, showed "an exact fit". The judge said although scientists agreed there was a connection, "the two graphs do not establish what Mr Gore asserts"
· Mr Gore said the disappearance of snow on Mt Kilimanjaro was expressly attributable to human-induced climate change. The judge said the consensus was that that could not be established
· The drying up of Lake Chad was used as an example of global warming. The judge said: "It is apparently considered to be more likely to result from ... population increase, over-grazing and regional climate variability"
· Mr Gore ascribed Hurricane Katrina to global warming, but there was "insufficient evidence to show that"
· Mr Gore also referred to a study showing that polar bears were being found that had drowned "swimming long distances to find the ice". The judge said: "The only scientific study that either side before me can find is one which indicates that four polar bears have recently been found drowned because of a storm"
· The film said that coral reefs all over the world were bleaching because of global warming and other factors. The judge said separating the impacts of stresses due to climate change from other stresses, such as over-fishing, and pollution, was difficult

Scientists developing clean energy systems from micro-algae

An international consortium established by an Australian scientist is developing a clean source of energy that could see some of our future fuel and possibly water needs being generated by solar-powered bio-reactors and micro-algae while absorbing CO2.
Sponsored Links (Ads by Google)
Renewable Energy - Learn the truth about solar, wind, hydro, bioenergy www.greenpeace.org.au
46 cent per gal BioDiesel - Not Biodiesel. No conversions. 30,000+ people Love this Answer DieselSecret.com
Top 5 Energy Stocks - Add some Green to your Portfolio. Free Alternative Energy Report. www.RisingStarStocks.com/Energy



Associate Professor Ben Hankamer, from the Institute for Molecular Bioscience (IMB) at The University of Queensland, has established the Solar Bio-fuels Consortium which is engineering green algal cells and advanced bio-reactor systems to produce bio-fuels such as hydrogen in a CO2-neutral process.
");
//]]>-->

document.context='YTowOnt9';

“The development of clean fuels to combat climate change and protect against oil price shocks is an urgent challenge facing our society,” said Associate Professor Hankamer, who co-directs the Consortium with Professor Olaf Kruse from the University of Bielefeld in Germany. “Many countries are already aiming to replace 10 to 20 percent of their existing energy production capacity with CO2-neutral energy systems by 2020. But this is very likely not nearly enough. “Some reports indicate that 50-66 percent of current energy production capacity may have to be CO2-free by 2020 to avoid the worst effects of climate change. This will be very hard to achieve and we need new technologies to do so.” Fuels make up about two-thirds of the energy market, yet most low-CO2 emission technologies, such as nuclear power and clean coal technology, target the electricity market. In contrast, the solar bio-hydrogen process uses solar-powered bioreactors filled with single-celled algae to produce hydrogen from water.
Sponsored Links (Ads by Google)
Tank Cleaning Underground Petroleum Tank Cleaning and Biofuel Tank Conversionswww.masstech.com.au
Lowest Electricity Cost Independent energy consultants Best market prices guaranteedwww.tteg.com.au
Complete Biodiesel Kits Turn-key Biodiesel Kits w/ Heat Have questions? Call 1-800-679-1398www.HomeBiodieselKits.com/BioKits



Algae naturally capture sunlight and use its energy to split water (H2O) into hydrogen and oxygen, however this process is not efficient enough to make it commercially viable. The Consortium uses this natural reaction, but is developing ways of enhancing its efficiency to a level where the process will be economically viable. This will be done with the help of a $286 000 Australian Research Council grant received last week. “We have conducted detailed feasibility studies that show that, once key technical milestones are overcome, this technology could achieve economic viability, which will increase further with the introduction of carbon trading schemes and the predicted rise in the oil price,” Associate Professor Hankamer said. “We have focused on micro-algae as a source of hydrogen because they have several advantages over traditional bio-fuel crops.” One major advantage, especially in drought-stricken countries like Australia, is that hydrogen can be produced from salt water. Marine and salt-tolerant algae can extract hydrogen and oxygen from seawater and on combustion these gases produce fresh water and electricity, which can be fed into the national grid. Consequently, clean energy production can theoretically be coupled with desalination. This is by no means the only advantage. One of the current concerns about traditional bio-fuel crops is that they will compete with food production for arable land and water. In contrast, algal bioreactors can be placed on non-arable land and use much less water than conventional bio-fuel crops. “This opens up new economic opportunities for arid regions and eliminates competition with agricultural crops or rainforest regions which are increasingly being used to plant oil palms for bio-diesel production,” Associate Professor Hankamer said. “Algae also have a very short life cycle and can be harvested every one to ten days rather than once or twice a year, increasing yield.” One other major benefit of the hydrogen production process is that it absorbs CO2. “We are therefore starting to investigate whether our hydrogen producing systems can be linked to conventional power stations to sequester CO2 which would otherwise be released into the atmosphere”, said Associate Prof Hankamer. For more information on the Consortium please visit http://www.solarbiofuels.org . Source: University of Queensland
» Next Article in General Science - Biology: Researchers help develop pest-resistant eggplant for South Asia


would you recommend this story?

Democrats eye key climate summit

By Roger Harrabin Environment analyst, BBC News

John Kerry has already stated that he will attend the Bali summit

A team of leading US Democrats is planning to send a delegation to a key UN climate conference to rival President Bush's official team.

They are so frustrated by Mr Bush's refusal to support US emissions cuts that they will travel to Bali to set out their alternative vision.

The UN summit in December is seen as a vital step towards a new global climate deal to replace the Kyoto Protocol.

The delegation may be led by House of Representatives Speaker Nancy Pelosi.

Her office has not confirmed or denied Ms Pelosi's travel plans, citing security reasons, but sources say she is keen to attend if the legislative schedule allows.

Details of the delegation are expected to be released in the next few days, but Senator John Kerry, the former presidential candidate and long-term environmentalist, has already publicly stated that he will make the trip.

Power struggle

While it is common for opposition politicians to attend meetings of the UN climate process, this delegation may take on greater significance as the Bush administration nears the end of its time in office and the Democrats' majorities in Congress prepare their strategy.

What happens in the corridors is just as important, maybe more important, than what happens in the negotiating hall Dr R K Pachauri, IPCC chairman

Soon, they will push through an Energy Bill that goes further than President Bush wants.

And they are set to introduce a Climate Change Bill in the Senate mandating binding carbon dioxide (CO2) cuts in the US; details of the bill should be published on 15 October.

The Democrat visit is welcome news to EU politicians, who have pledged to cut Europe's emissions by an ambitious 30% by 2020 from 1990 levels if other big nations make similar effort.

Big developing nations like China, India, Brazil, South Africa and Mexico are refusing to make any international commitments while the US refuses to move.

Climate negotiators from Europe and Africa have told BBC News that a Democrat presence in Bali would be very welcome. They said it could apply pressure on President Bush's representatives in the negotiating hall.

Last week, Sigmar Gabriel, the German environment minister, said he had visited Mr Bush's Washington meeting on climate change and that he had enjoyed very fruitful discussions with the Democrats about the shape of US climate policy.

Dr R K Pachauri, head of the Intergovernmental Panel on Climate Change (IPCC), observed: "I think it's very important for legislators from every country to be exposed to what's going to happen in Bali.

"In a Conference of the Parties (COP), what happens in the corridors is just as important, maybe more important, than what happens in the negotiating hall," he told BBC News.

"I would like to see legislators from China and India taking part, too."