US oil burn begins as wind turns for the worst

US Coast Guard issued photo shows debris and oil from the Deepwater Horizon drilling platform floating in the Gulf of Mexico following the sinking of the rig on April 22. (AFP)

NEW ORLEANS, Louisiana (AFP) – Crews began controlled burns of a giant oil slick in the Gulf of Mexico, but a cruel wind shift raised fears the spill could hit Louisiana's fragile shores by the weekend.

The leading edge of the crude was about 16 miles (26 kilometers) off the Louisiana coast by Wednesday evening and winds were expected to strengthen and crucially change direction on Thursday, blowing it towards the coast.

Two skimming vessels dispatched by the US Coast Guard and energy giant British Petroleum (BP) swept the thickest concentrations of oil in the center of the slick into a 500-foot (150-meter) fire-resistant boom.

They then towed it to a five-mile (8-kilometer) "burn zone" inside the slick, roughly 50 miles (80 km) south of the mouth of the Mississippi, where it was set alight by a fuel source on a special float and allowed to burn for approximately one hour.

Similar efforts on past spills have succeeded in burning off between 50 and 90 percent of the oil captured and if Wednesday's "trial" goes well, crews plan to conduct several more in the coming days to keep the slick at bay.

The decision to start burning the slick, which has a 600-mile (965-kilometer) circumference, gained even greater import when US government weather experts warned that stronger southeasterly winds were forecast from Thursday night through Saturday.

"These onshore winds will move floating oil towards the delta with possible shoreline impacts by Friday night," a National Oceanic and Atmospheric Administration (NOAA) forecast chart presented to journalists warned.

Charlie Henry, the NOAA's scientific support coordinator, said there is a "high risk" southeast winds will push emulsified oil and "tar balls" into the delta area by Friday night.

If large quantities of the crude, which is leaking from the debris of a rig that sank after a deadly explosion last week, drift into Louisiana's marshy wetlands, mopping it up would be next to impossible.

It would be disastrous for natural parks full of waterfowl and rare wildlife and could also imperil the southern state's 2.4-billion-dollar a year fisheries industry, which produces a significant portion of US seafood.

As miles of inflatable booms were set up around the Mississippi delta to protect the Louisiana coast, Governor Bobby Jindal evoked memories of Hurricane Katrina, which devastated his southern state in August 2005.

"We must hope for the best and prepare for the worst," Jindal said, after being given a flyover of the spill. "We're approaching this situation just as we would do before a hurricane comes ashore.

"We're doing everything we can to protect the livelihood of our citizens who make their living in the fishing industry and the wildlife that grace our coastal areas."

Oil, at the rate of 42,000 gallons (158,987 l.) a day, is spewing from the riser pipe that connected the Deepwater Horizon platform to the wellhead before the rig sank last Thursday, two days after a huge explosion that killed 11 workers.

The accident has not disrupted offshore energy operations in the Gulf, which accounts for 30 percent of all US oil production and 11 percent of domestic gas production.

BP, which leased the semi-submersible rig from Houston-based contractor Transocean, has been operating four robotic submarines some 1,500 meters (5,000 feet) down on the seabed to try and cap the well.

They have failed so far to fully activate a giant 450-tonne valve, called a blowout preventer, that should have shut off the oil as soon as the disaster happened but only partially reduced the flow.

As a back-up, engineers are frantically constructing a giant dome that could be placed over the leaks to trap the oil, allowing it to be pumped up to container ships on the surface.

Another Transocean drilling rig is also on stand-by to drill two relief wells that could divert the oil flow to new pipes and storage vessels.

But that would take up to three months and the dome is seen as a better interim bet even though engineers need two to four weeks to build it.

Coast Guard Rear Admiral Mary Landry, who is leading the government's response to the disaster, has warned that if the well is not secured the spill could end up being one of the worst in US history.

Landry said the oil burn was "just one tool in a tool kit" of plans.

Skimming vessels have mopped up tens of thousands of gallons of crude and jets of dispersant chemical have been dropped from planes in dozens of sorties to aid the evaporation process.

But until the leaks are sealed or the well is capped, 1,000 barrels of oil a day will continue to shoot into the sea from the rich supply below the seabed.

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