Interstellar Space Molecules That Help Form Basic Life Structures Identified

Using various telescopes in La Palma (including the Telescopio Nazionale Galileo) and Texas, IAC researchers have detected the presence of naphthalene in the interstellar medium in the direction of the star Cernis 52 in the constellation Perseus. This molecule consists of two hexagonal rings of carbon atoms surrounded by hydrogen atoms. (Credit: Sources: Miguel Briganti (IAC), Digital Sky Survey, David Barrado. Credits: Gabriel Pérez, Multimedia Service/IAC)

A team of scientists led by researchers from the Instituto Astrofísica de Canarias (IAC) has succeeded in identifying naphthalene, one of the most complex molecules yet discovered in the interstellar medium. The detection of this molecule suggests that a large number of the key components in prebiotic terrestrial chemistry could have been present in the interstellar matter from which the Solar System was formed.

IAC researchers Susana Iglesias Groth, Arturo Manchado and Aníbal García, in collaboration with Jonay González (Paris Observatory) and David Lambert (University of Texas) have just published these results in Astrophysical Journal Letters.

The naphthalene was discovered in a star formation region in the constellation Perseus, in the direction of the star Cernis 52. “We have detected the presence of the naphthalene cation in a cloud of interstellar matter located 700 lightyears from the Earth”, says IAC researcher Susana Iglesias Groth. The spectral bands found in this consstellation coincide with laboratory measurements of the naphthalene cation.

Iglesias Groth further adds, “we aim to investigate whether other, more complex, hydrocarbons exist in the same region, including aminoacids”. When subjected to ultraviolet radiation and combined with water and ammonium, both very abundant in the interstellar medium, naphthalene reacts and is capable of producing a wide variety of aminoacids and naphthaloquinones, precursor molecules to vitamins.

All these molecules play a fundamental role in the development of life as we know it on Earth. In fact, naphthalene has been found in meteorites that continue to fall to the surface of the Earth, and which fell with much greater intensity in epochs preceding the appearance of life.

The work of these researchers also enables us to understand one of the most intriguing problems in interstellar medium spectroscopy. For the past 80 years, the existence has been known of hundreds of spectroscopic bands (the so-called “diffuse bands”) associated with interstellar matter, but the identification of the agent causing them has remained a mystery.

“Our results show that polycyclic aromatic hydrocarbons such as naphthalene are responsible for the diffuse bands and should be present throughout the interstellar medium”, says Iglesias Groth.

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Astrophysicists 'Weigh' Galaxy's Most Massive Star

Astrophysicists successfully "weighed" a star of a binary system with a mass 116 times greater than that of the Sun. Located in the massive star cluster NGC 3603, the supermassive star system, known under the name of A1, has a rotation period of 3.77 days. (Credit: CRAQ)

Theoretical models of stellar formation propose the existence of very massive stars that can attain up to 150 times the mass of our Sun.

Until very recently, however, no scientist had discovered a star of more than 83 solar masses. Now an international team of astrophysicists, led by Université de Montréal researchers from the Centre de recherche en astrophysique du Québec (CRAQ), has found and "weighed" the most massive star to date.

Olivier Schnurr, Jules Casoli and André-Nicolas Chené, all graduates of the Université de Montréal, and professors Anthony F. J. Moffat and Nicole St-Louis, successfully "weighed" a star of a binary system with a mass 116 times greater than that of the Sun, waltzing with a companion of 89 solar masses, doubly beating the previous record and breaking the symbolic barrier of 100 solar masses for the first time.

Located in the massive star cluster NGC 3603, the supermassive star system, known under the name of A1, has a rotation period of 3.77 days. The masses were calculated by a combination of observations made with the SINFONI instrument, an integral field spectrograph operating on the Very Large Telescope on the site of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) in Chile, and infrared images coming from the Hubble Space Telescope.

The stars forming the A1 system are so massive and bright that the light they transmit shows characteristics that only "Wolf-Rayet" stars possess. A Wolf-Rayet star is a hot, massive and evolved star exhibiting a very high loss of mass due to a strong stellar wind (similar to the solar wind). Within the context of this work, a binary system transmitting X-rays at a power almost never seen in our Galaxy was also discovered near NGC 3603-A1.

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How many planets are there in our solar system anyway?

A. Feild / STScI / NASA / ESA

An artist's conception shows the dwarf planet Haumea and its two moons, Hi'iaka and Namaka.

So just how many planets are there in our solar system anyway? Eight? Nine? Thirteen? Or thousands? Far from settling the question, the "Great Planet Debate" has revealed just how complex and interesting the question is.

The planethood question got more interesting this week with the naming of yet another dwarf planet, Haumea. It's traditional to name planets after mythological deities - and Haumea, the Hawaiian goddess of childbirth and fertility, follows that formula.

The football-shaped world was found by Caltech astronomer Michael Brown just after Christmas 2004 (which prompted its initial, unofficial nickname: "Santa"). Haumea's discovery was shrouded in a scientific controversy that Brown recaps in his Weblog. At the time, controversy surrounded its planetary status as well, because it added to a growing class of objects in the same general class as Pluto. Astronomers surmised that hundreds of Pluto-scale objects may lurk on the icy rim of the solar system's disk, known as the Kuiper Belt.

The controversy came to a head in 2005 when Brown's team found the object now known as Eris - a world like Pluto, only bigger and farther out. All this led the International Astronomical Union to agonize over where to draw the line on planethood. In 2006, the IAU came up with a definition aimed at putting the solar system's eight biggest planets in one class, and Pluto in a different class with Eris and other dwarf planets or "plutoids."

The Great Planet Debate has been simmering ever since. In August, astronomers held a teach-in on the subject at Johns Hopkins University's Applied Physics Laboratory, which is the base of operations for NASA's New Horizons mission to Pluto. One of the purposes of the meeting was to see how teachers were handling the planethood question.

Scientist (and parent) sees 'teaching moment'
The education angle literally hit home for planetary scientist Alan Stern - and not just because he's the principal scientific investigator for New Horizons.

"My own son was told by a teacher that an answer was wrong on a test about Pluto," Stern told me last week. According to the test, the "right" answer for the number of planets in the solar system was eight - but Stern said that August's installment of the Great Planet Debate proved that the question was still up for grabs, even among educators.

"It was clear at the end of the two and a half days that there was no consensus," he said. "We're in transition. I think that's a teaching moment."

Stern has long argued that the IAU's definition of planethood provided more confusion than clarification. "There's a lot of unhappiness with the IAU's solution," he said. "I didn't hear anybody say, 'Oh, I think it's the cat's meow.'"

He maintains that it's wrong to think about the solar system as if there were a sharp division between eight planets and everything else. Even dwarf planets are still planets - and in Stern's mind, they may be more representative of the planetary spectrum than the eight biggies.

"It's the most populous class of planets in the solar system," Stern said. "Pluto's no longer the misfit."

There's something about Haumea
The fact that the IAU is giving names to dwarf planets - Pluto, Eris, Ceres, Makemake and now Haumea - shouldn't make a difference in the debate, Stern said. In fact, it totally makes sense. "From our perspective, these are planets. They deserve names," he said.

Stern has often compared the definition of planets with the definition of rivers: Sure, there might be six great rivers in the world ... or are there 14? In any case, that doesn't mean you have to set the Maquoketa River or thousands of other streams apart as "dwarf rivers." Every river, great or small, has its own special appeal - and it's the same with planets.

In fact, Haumea may be one of the most endearing little planets out there: Caltech's Brown has said it's his "favorite object in the solar system," in part because of its fast, end-over-end spin, the elongated shape it has as a result, and also because of its tightly orbiting satellites (which have been named Hi'iaka and Namaka, after two of the goddess Haumea's children). Brown said additional bits of ice and rock were apparently struck off Haumea in a cosmic collision long ago and are now circling the sun in their own orbits.

New Horizons gets a transplant ... and Twitter!
Oodles of such oddities may well come to light when the New Horizons spacecraft makes its way through the Kuiper Belt, starting in seven years. Last week, the probe underwent a successful "brain transplant" that upgraded the onboard software. It's now more than a billion miles from Earth, flying toward Pluto at a rate of about a million miles a day.

You can keep up with the mission's progress via Twitter or Facebook. (In the wake of Phoenix Mars Lander's Twitter success, it seems as if every space mission nowadays is getting into social networking.)

New Horizons' team will be checking out the spacecraft's instruments over the next couple of months, and then put the probe back to sleep for another months-long nap. The first "dress rehearsal" for the Pluto flyby will be conducted next year, but there's still a long way to go before showtime in 2015.

Will the planethood debate be settled by that time? Stern won't be surprised if it isn't. After all, it took decades for scientists to settle the controversy over continental drift - and some are still going back and forth over the implications of climate change and evolutionary biology.

"This is not atypical," Stern said. "It's just one of the most visible topics on the table right now."

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New Energy-Efficient Process Turns Sugar into Gasoline

Written by Alex Felsinger

Using microscopic metal particles, scientists from the University of Wisconsin-Madison have found that plant-based sugar can be converted to gasoline to be used in current engines. The substance is cleaner-burning than petroleum-based gasoline and more stable than ethanol.

While a method to turn sugar to gas already exists, it requires extremely high temperatures which made the process less energy efficient. The new process converts the sugars to fuel in mere minutes by running a mixture of water and sugar over particles of the precious metals platinum and rhenium. The metal atoms break the chemical bonds in sugar and release oxygen, which leaves a mixture including carbon and hydrogen that can be used to make plastics or gasoline. Even the gas byproducts of the process can be used as a replacement for natural gas.

The scientists have only tested the process in laboratory setting, and before wide-scale use, the process faces the same problem as other biofuels: where to acquire the sugar. The process uses the simple sugar compound sorbitol, which is available but difficult to separate from biomass. “We would just intercept the sugar and go to gasoline,” said James Dumesic, the chemical engineer from the University of Wisconsin-Madison who led the study. “But there’s still a lot of work to do on how to go from cellulose to sugar.”

The metals used in the process are cost-prohibitive, but the researchers are unsure how much of the metal would be required for mass production. In the meantime they are studying how the metals react with the sugar in hopes to find cheaper metals that produce similar reactions.

Photo Credit: knaakle on Flickr under Creative Commons license.

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Fingers and toes evolved from fins say scientists

Fingers and toes evolved from fins. TOP - Panderichthys - a 90-130 cm long fish from the Devonian period 380 million years ago (Wikimedia Commons License). BELOW - Flapping fins and showing off ... look-at-me antics are typical of young male humpbacks off the coast of Port Stephens. Picture: Ray Alley (image digitally manipulated).

SCIENTIST have traced the origin of fingers and toes to fish-like creatures that roamed the seas 380 million years ago, according to a new study.

The findings, published today in the British-based science journal Nature, upend the prevailing theory on the evolution of digits.

It had long been assumed that the first creatures to develop primitive fingers were tetrapods, air-breathing animals that crawled from sea to land some 10 to 20 million years later.

The need to adapt to swampy marshlands and terra firma, the theory went, is what drove the gradual shift through natural selection from fish fins suitable only for swimming to weight-bearing limbs with articulated joints.

The study, however, reveals that rudimentary fingers were already present inside the fins of the shallow-water Panderichthys, a transitional species that was nonetheless more fish than tetrapod.

"What we have shown is that the hand and the foot emerge from pre-existing bits of the fin skeleton that were just reshaped, rather than being entirely new bits that were bolted onto the existing fin skeleton,'' said co-author Per Ahlberg, a researcher at Uppsala University in Sweden.

The discovery did not come from a new archeological find but from the reexamination of existing fossils, he said.

Previous research, it turns out, had simply overlooked what was there.

"The problem is that all good specimens of Panderichtys come from one location'' - a brick quarry in Latvia - "where the clay is almost exactly the same color as the bones,'' he said.

"With a nice big bone, that is not a problem. But if you are interested in tiny, fragile bones at the outer end of the fin skeleton, it is nearly impossible to see what is going on.''

Scientists had been thrown further off the track by the morphology of another animal from the Devonian period, which spanned from 360 to 416 million years ago.

In most ways, Tiktaalik seemed even closer to the true air-breathing tetrapods that first colonized firm land than Panderichtys, and yet its fins remained largely fish-like, lending even more credence to the theory that proto-fingers came during, not before, the transition to land.

But recent research in genetics had suggested that rudimentary digits might have emerged further back along the evolutionary tree than once suspected.

A gene that plays a key role in patterning the hands and feet in mice, for example, was found to express itself similarly in modern-day lung fish, a distant but direct cousin of the tetrapods that first crawled out of the sea.

So Mr Ahlberg and two colleagues decided it was worth taking a closer look at Panderichthys using a new technique.

They ran a specimen, still embedded in clay, through a CT scanner at a hospital.

"We could see the internal skeleton very clearly, and were able to model it without ever physically touching the specimen,'' Mr Ahlberg said.

The image shows stubby bones at the end of the fin skeleton clearly arrayed like four fingers, called distal radials. There are no joints, and the bones are quite short, but there could be no doubt as to what they were.

"This was the key piece of the puzzle that confirms that rudimentary fingers were already present in the ancestors of tetrapods,'' said lead author Catherine Boisvert, also of Uppsala University.

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Plastic-Munching Bugs Turn Waste Bottles Into Cash

By COLIN BARRAS

Newly discovered bacterial alchemists could help save billions of plastic bottles from landfill. The Pseudomonas strains can convert the low-grade PET plastic used in drinks bottles into a more valuable and biodegradable plastic called PHA.

Although billions of plastic bottles are made each year, few are ultimately recycled because the typical recycling process converts low value PET bottles into more PET.

(AP)

PHA is already used in medical applications, from artery-supporting tubes called stents to wound dressings.

The plastic can be processed to have a range of physical properties. However, one of the barriers to PHA reaching wider use is the absence of a way to make it in large quantities.

The new bacteria-driven process – termed upcycling – could address that, and make recycling PET bottles more economically attractive.

PET bugsAlthough billions of plastic bottles are made each year, few are ultimately recycled. Just 23.5% of US bottles were recycled in 2006.

This is because the recycling process simply converts the low value PET bottles into more PET, says Kevin O'Connor at University College Dublin, Ireland.

"We wanted to see if we could turn the plastic into something of higher value in an environmentally friendly way," he says.

O'Connor and colleagues knew that heating PET in the absence of oxygen – a process called pyrolysis – breaks it down into terephthalic acid (TA) and a small amount of oil and gas.

They also knew that some bacteria can grow and thrive on TA, and that other bacteria produce a high-value plastic PHA when stressed. So they wondered whether any bacteria could both feed on TA and convert it into PHA.

Bacteria hunt "It was a long shot to be honest," says O'Connor. His team studied cultures from around the world known to grow on TA, but none produced PHA. So they decided to look for undiscovered strains, in environments that naturally contain TA.

Analysing soil bacteria from a PET bottle processing plant, which are likely to be exposed to small quantities of TA, yielded 32 colonies that could survive in the lab using TA as their only energy source.

After 48 hours they screened each culture for PHA. Three cultures, all similar to known strains of Pseudomonas, accumulated detectable quantities of the valuable plastic.

The next step is to improve the efficiency of the process, says O'Connor. "A quarter to a third of each cell is filled with plastic – we want to increase that to 50 to 60%."

Less landfill Sudesh Kumar, a microbiologist at the University of Science, Malaysia, in Penang, is impressed with the study.

"There are many other systems that are economically more viable to produce PHA with better material properties," he says. "But Kevin's work offers an interesting novel approach to solve the problem of PET accumulation in landfill dumps."

But it is still unlikely that using the new approach alone will appeal to industry, O'Connor says.

"Working with this kind of environmental technology in isolation, the chances of success are reduced," he says. The best approach, he continues, would be to use the new bacteria as just one part of a bio-refinery capable of upcycling an array of waste products in an environmentally friendly way.

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Global Warming's Ecosystem Double Whammy

Tall grass in Oklahoma. (Credit: iStockphoto/Justin Voight)

Plants and soils act like sponges for atmospheric carbon dioxide, but new research finds that one abnormally warm year can suppress the amount of carbon dioxide taken up by some grassland ecosystems for up to two years. The findings, which followed an unprecedented four-year study of sealed, 12-ton containerized grassland plots at DRI is the cover story in this week's issue (September 18) of the journal Nature.

"This is the first study to quantitatively track the response in carbon dioxide uptake and loss in entire ecosystems during anomalously warm years," said lead author Jay Arnone, research professor in the Division of Earth and Ecosystem sciences at DRI. "The 'lagged' responses that carry over for more than one year are a dramatic reminder of the fragility of ecosystems that are key players in global carbon sequestration."

The plants and soils in ecosystems help modulate the amount of carbon dioxide (CO₂) in the atmosphere. Plants need CO₂ to survive, and they absorb most CO₂ during spring and summer growing seasons, storing the carbon in their leaves, stems and roots. This stored carbon returns to the soil when plants die, and it is released back into the atmosphere when soil bacteria feed on the dead plants and release CO₂.

The four-year DRI study involved native Oklahoma tall grass prairie ecosystems that were sealed inside four, living-room-sized environment chambers. The dozen 12-ton, six-foot-deep plots were extracted intact from the University of Oklahoma's prairie research facility near Norman, Okla., in order to minimize the disturbance of plants and soil bacteria. Inside the DRI's sunlit-controlled EcoCELL chambers, scientists replicated the daily and seasonal changes in temperature, and rainfall that occur in the wild.

In the second year of the study, half of the plots were subjected to temperatures typical of a normal year, and the other half were subjected to abnormally warm temperatures -- on the order of those predicted to occur later this century by the Intergovernmental Panel on Climate Change. In the third year of the study, temperatures around the warmed plots were turned down again to match temperatures in the control plots. The CO₂ flux -- the amount of carbon dioxide moving between the atmosphere and biosphere -- was tracked in each chamber for all four years of the study.

DRI's EcoCELL facility gave the scientists an unprecedented degree of control over the enclosed ecosystems. Not only could they create the same air temperature conditions from year-to-year, they could also independently control the soil temperature in each chamber -- a key feature that enhanced the ecological relevance of the results. Each containerized ecosystem also sat on "load cells," the type of scales used to weigh trucks on highways. Scientists used the scales to track the amount of water that was taken up and lost by the plants and soil in both normal and abnormal years. Thus, each containerized ecosystem served as a weighing lysimeter, an instrument that's used to measure the water and nutrients that percolate through soils.

The scientists found that ecosystems exposed to an anomalously warm year had a net reduction in CO₂ uptake for at least two years. These ecosystems trapped and held about one-third the amount of carbon in those years than did the plots exposed to normal temperatures.

"Large reductions in net CO₂ uptake in the warm year were caused mainly by decreased plant productivity resulting from drought, while the lack of complete recovery the following year was caused by a lagged stimulation of CO₂ release by soil microorganisms in response to soil moisture conditions," explained co-author Paul Verburg, also from DRI.

Numerous studies have found that the Earth's atmospheric CO₂ levels have risen by about one-third since the dawn of the Industrial Age. CO₂ helps trap heat in the atmosphere, and political and economic leaders the world over are debating policy and economic reforms to reduce the billions of tons of CO₂ that burned fossil fuels are adding to the atmosphere each year.

"Our findings confirm that ecosystems respond to climate change in a much more complex way than one might expect based solely on traditional experiments and observations," said study co-author James Coleman, vice provost for research and professor of ecology and evolutionary biology at Rice University. "Our results provide new information for those who are formulating science-based carbon policies."

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LiFePO4 Batteries: A Breakthrough For Electric Vehicles

Soon, we’ll probably be seeing Lithium Iron Phosphate (LiFePO4) batteries being used in most electric cars and bikes. This new battery type is set to dominate the market. Based upon lithium ion technology, LiFePO4 batteries offer many advantages over lithium cobalt dioxide (LiCoO2) batteries which are commonly used in laptops, mp3 players and cell phones. In electric vehicles, LiFePO4 batteries offer greater range, power and safety.

LiFePO4 batteries also offer faster charging rates, and they provide full power until they are completely discharged. LiFePO4 chemistry is also environmentally friendly — it’s the least toxic of all the battery types.

A Graph Showing The Energy Density Of Various Batteries Types

LiFePO4 batteries were developed by Dr. John Goodenough at the University of Texas. These batteries have seen wide acceptance recently in Asian countries, but still have not made inroads in the U. S. marketplace. However, you can find these batteries being sold on eBay for electric bikes and scooters.

For electric vehicles and plug-in electric cars, the LiFePO4 batteries will typically perform well in temperatures up to 400-degrees F, last for 6 to 7 years at a charge-discharge cycle of over 3,000.

The biggest player in the LiFePO4 marketplace for electric vehicles, however, is A123 Systems that has teamed up with GM to develop these batteries for the Chevy Volt plug-in hybrid. Another big player is Lithium Technology Corporation who has been working with GM, Toyota and U. C. Davis to develop LiFePO4 batteries for all-electric and hybrid vehicles.

Here’s a list of all the advantages of LiFePo4 batteries:

• Safe technology — will not catch fire or explode with overcharge

• Over 2000 discharge cycles life compared to typically around 300 for lead acid

• Double the usable capacity of similar amp hour lead acid batteries

• Virtually flat discharge curve means maximum power available until fully discharged (no “voltage sag” as with lead acid batteries)

• High discharge rate capability, 10C continuous, 20C pulse discharge

• Unlike lead acid batteries, can be left in a partially discharged state for extended periods without causing permanent damage

• Extremely low self discharge rate (unlike lead acid which will go flat quite quickly if left sitting for long periods)

• Does not suffer from “thermal runaway”

• Can be used safely in high ambient temperatures of up to 60C without any degradation in performance

• Maintenance free for the life of the battery

• Can be operated in any orientation

• Does not contain any toxic heavy metals such as lead, cadmium, nor any corrosive acids or alkalies thus making LiFePO4 batteries the most environmentally friendly battery chemistry available

• LiFePO4 cells are of solid construction — there are no fragile/brittle plates made of lead which can be prone to failure over time as a result of vibration

• Can be safely rapidly recharged — when fully discharged can be brought to a state of over 90% fully charged in 15 minutes

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Cities rethink wisdom of 50s-era parking standards

By SARAH KARUSH, Associated Press Writer

WASHINGTON - Alice and Jeff Speck didn't have a car and didn't want one. But District of Columbia zoning regulations required them to carve out a place to park one at the house they were building.

It would have eaten up precious space on their odd-shaped lot and marred the aesthetics of their neighborhood, dominated by historic row houses. The Specks succeeded in getting a waiver, even though it took nine months.

Like nearly all U.S. cities, D.C. has requirements for off-street parking. Whenever anything new is built — be it a single-family home, an apartment building, a store or a doctor's office — a minimum number of parking spaces must be included. The spots at the curb don't count: These must be in a garage, a surface lot or a driveway.

D.C. is now considering scrapping those requirements — part of a growing national trend. Officials hope that offering the freedom to forgo parking will lead to denser, more walkable, transit-friendly development.

Opponents say making parking more scarce will only make the city less hospitable. Commuters like Randy Michael of Catharpin, Va., complain they are already forced to circle for hours in some neighborhoods.

"Today I had an 11:30 meeting and I had to plan an extra hour just to park" said Michael, 49. It ended up taking him 40 minutes to find a metered spot.

Advocates counter that parking is about more than drivers' convenience; it can profoundly affect the look and feel of a city.

"Do you want to look like San Francisco or Los Angeles?" asked Donald Shoup, an urban planning professor at UCLA and author of "The High Cost of Free Parking." "New York or Phoenix?" (Shoup prefers San Francisco and New York — hard to park in but highly walkable.)

Parking requirements — known to planners as "parking minimums" — have been around since the 1950s. The theory is that if buildings don't provide their own parking, too many drivers will try to park on neighborhood streets.

In practice, critics say, the requirements create an excess supply of parking, making it artificially cheap. That, the argument goes, encourages unnecessary driving and makes congestion worse. The standards also encourage people to build unsightly surface lots and garages instead of inviting storefronts and residential facades, they say. Walkers must dodge cars pulling in and out of driveways, and curb cuts eat up space that could otherwise be used for trees.

"Half the great buildings in America's great cities would not be legal to build today under current land use codes," said Jeff Speck, a planning consultant. "Every house on my block is illegal by current standards, particularly parking standards."

Opponents also say the standards force developers to devote valuable land to parking, making housing more expensive.

Milwaukee, one of a small group of cities that has eased minimum parking requirements, did so because they were impeding redevelopment of struggling neighborhoods, said John Norquist, the city's mayor from 1988 to 2004.

Norquist, who today heads the Chicago-based Congress for the New Urbanism, described a lot that sat vacant for decades after a historic building burned down. The required parking made it unfeasible to build anything new there, he said. After officials relaxed the parking requirement, a thriving restaurant sprang up.

Some cities have switched directions altogether, replacing the minimum requirement with a cap on the maximum allowable number of parking spaces. London and San Francisco began making the shift decades ago. San Francisco is currently considering extending the new approach to more neighborhoods.

Activists say too much parking is required even in New York City, particularly outside Manhattan. In August, a coalition of environmental groups said existing parking minimums would boost traffic and cancel out much of the expected improvements from the city's green initiatives.

The D.C. proposal would eliminate minimum parking requirements with some exceptions. Caps on parking would also be established.

In old D.C. neighborhoods like Capitol Hill and Georgetown, where parking is scarce, opponents of the change fear that if new homes don't provide off-street spots, competition for on-street parking will worsen.

Ken Jarboe, a neighborhood leader from Capitol Hill, said the way to reduce traffic is to continue improving the transit system and to create incentives for people not to drive.

"Simply saying, 'Let's make it more painful to park — it doesn't get you where you want to be," Jarboe said.

But Harriet Tregoning, director of the D.C. Planning Department, said the city is already easy to navigate without a car. Nine out of 10 residents live within a quarter-mile of transit, and, according to census data, 12 percent of Washingtonians walk to work, Tregoning noted. More than a third of D.C. households don't have a car.

The Specks say they haven't regretted their decision to go car-free even after the birth of their son, Milo, in June. They walk to shops and parks in their neighborhood, and the baby's pediatrician is a short bus ride away. When needed, they can rent vehicles from Zipcar, a car-sharing service.

Adding a garage and a driveway to their house would have forced them to sacrifice the equivalent of a bedroom and their garden. They decided it was worth spending the time to get a variance, especially since they were applying for several other zoning waivers at the same time.

For a developer, however, seeking a variance may not be an option.

"If you're working off borrowed money, you're not going to wait nine months," Jeff Speck said.

As a result, developers of some recent D.C. projects have ended up with more parking than actually gets used, Tregoning said.

"We're forcing people to invest in spaces for automobiles rather than in spaces for people," she said. "There's no way to recover that use."

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N.Y. Tests Turbines to Produce Power

By Robin Shulman

In this 2006 photo, a Verdant Power turbine is lowered into the river off Roosevelt Island. This one failed. (Associated Press)

NEW YORK -- On a recent morning, a crane sank a 16-foot rotor into the waters of the East River and divers swam deep to bolt it to the bottom. By early evening, as the northerly current sped up, the rotor began to spin, a big thunk sounded in the control room, a green light went on, and electricity began to pour into a nearby supermarket.

The scene represents an experiment in tidal power, using turbines that look like underwater windmills, and it is the first of its kind nationwide and one of only a few such pilot projects in the world.

"This is just the beginning of a project, but the project itself is emblematic of a whole new industry," said Trey Taylor, the president of Verdant Power, a small company that created the experiment and hopes to expand it to commercial use with 300 turbines in the East River that could power up to 10,000 homes in the city.

Engineers, policymakers and energy experts say projects like the East River tidal turbines are already placing this city at the urban vanguard of energy production. They say New York City is uniquely positioned to advance sustainable energy projects because of the city's enormous need for power, its high electricity costs, and the pressure for new sources created by its unusual rule that 80 percent of energy must be generated within the city.

Mayor Michael R. Bloomberg has sought to make New York the cleanest and greenest major city in the country. He has faced setbacks -- for example, when his congestion pricing plan to reduce the number of cars in Manhattan was killed by the state legislature. He was mocked when he spoke of placing windmills on bridges and skyscrapers, and a few New York tabloids ran illustrations of wind turbines on the Brooklyn Bridge and the Empire State Building.

Still, he has asked private companies to submit ideas to develop wind, solar and water energy projects. And for the past year, his administration has supported the water turbines, a project many years in the making.

The idea is simple: As water flows, it spins the rotors and produces electricity. The turbines run according to the tide charts, which are as predictable as phases of the moon.

The idea was rejected for state funding in 2000, only to be accepted a few years later.

The strength of the flows of the East River -- which is technically not a river, but a tidal strait, whose current switches direction throughout the day -- makes it an ideal spot for generating power. The strength of the current also makes it hard on equipment. Swift-moving waters chewed up the first two types of turbines, which Verdant, a small, private company, installed in late 2006 and early 2007.

The first blades were fiberglass with a steel skeleton. Later, another set of rotors was made from aluminum and magnesium.

"The water was very powerful, so it broke the rotors," Taylor said.

The newest blades are made from an aluminum alloy, attached to rotors whose strength has been extensively tested. If all holds together, Taylor expects to apply for permission to expand and launch a commercial operation.

But the capacity of the turbines is not the only stumbling block. There were years of environmental testing on the site, including an investment of more than $2 million to monitor the impact on fish and migratory birds. Both have avoided the big, clunky turbines thus far, Taylor said, but regulations require ongoing inspections.

The city needs new ways to generate energy because existing transmission lines from upstate are inadequate and the city's needs are growing, said James Gallagher, energy expert at the city's Economic Development Corp.

"We need generation within the city, and anything we can add in terms of clean, efficient, new generation, has a value to it," he said.

He and other analysts say tidal power is a small piece of the city's energy equation. In fact, New York is learning the rules of the game for its own brand of urban sustainable energy production: The winds and waters of this port city can be harnessed, but only in certain places. Tidal power is reliable, but small-scale. Wind power is cheap but rare. Solar power is unreliable, inconstant and expensive but easy to install.

Experts warn that before these alternatives are widely adopted, New York will have to upgrade its antiquated grid system, which is currently incapable of incorporating a great deal of power from multiple small sources.

The city's peak energy consumption is 12,000 megawatts at any given moment, said Stephen Hammer, the director of the Urban Energy Program at Columbia University. "The question is, 'What's our goal? How much of that 12,000 megawatts total do we want to try to achieve? What kind of cost burden do we want to bear to achieve it?' "

So far, support has been relatively strong on Roosevelt Island, the quiet community between Manhattan and Queens that is the project's base. Developers began building that support in 2001, long before any installation, beginning with neighborhood meetings.

"I think it's a great thing," said Pia Doane, 63, speaking as she shopped for fruit at the Gristede's supermarket the project powers. She said she'd rather live in view of a turbine than a smokestack, such as those at the massive power plant just across the water, which she calls Asthma Alley. "This current has a big force," she said. "We should use it."

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