Wednesday, April 28, 2010

Spill Response: Burn Baby Burn

As federal officials prepare to test whether they can ignite a patch of the oil slick spreading from the seafloor wreckage of the Gulf of Mexico well, seasoned specialists say the logic in pursuing this option is clear and well established by decades of testing.

Environment Canada

In 1993, Canadian and American government scientists conducted a test burn of an oil slick off the coast of Newfoundland.One of the biggest such tests was undertaken off Newfoundland in 1993. Called the Newfoundland Offshore Burn Experiment, the joint Canadian and American project concluded that combustion consumed most of the more problematic compounds and the levels of harmful compounds in smoke were below danger thresholds outside 150 yards of so of the fire zone. The water beneath the burn area showed no detectable levels of harmful compounds. I’ve appended the summary at the bottom of this post.

I spoke this morning with David F. Dickins about burning spilled oil. He’s an environmental engineer who’s a veteran of decades of spill cleanups and studies. I first interviewed him for our “Big Melt” series on the implications of the growing human push into the warming Arctic in search of oil and gas and shipping routes. (He’s done tests of oil cleanup methods that may be needed in Arctic waters — and sea ice — someday.) He’s very bullish on burning where possible:

I really believe that if there’s any possibility of burning the oil on the surface that should absolutely be carried out and attempted. There are huge net environmental benefits compared to letting it stay on the surface or hit the coast. There’s lots of evidence that there are no human health risks. After burning, there are fewer carcinogens and toxics than in the actual original oil. You really have a chance to remove 70, 80 or 90 percent of the oil. No other technique is going to take that much oil out of the environment.

Nancy Rabalais, who studies pollution impacts on coastal ecosystems and led a study of oil impacts for the National Academy of Sciences, deferred on weighing the wisdom of burning, but said that if the oil crosses the 23 remaining miles of sea and soaks the fragile coastline, substantial impacts are inevitable. “If this hits shore, with all the sea-grass beds and marshes, it will be a mess,” she told me this morning.

Here’s the Newfoundland project summary:
A group of 25 agencies from Canada and the United States conducted a major offshore burn experiment near Newfoundland, Canada. Two lots of oil, about 50 cubic meters (50 tons) each, were released into a fireproof boom. Each burn lasted over an hour and was monitored for emissions and physical parameters. Over 200 sensors or samplers were employed to yield data on over 2000 parameters or substances. The operation was extensive; more than 20 vessels, 7 aircraft and 230 people were involved in the operation
at sea.

The quantitative analytical data show that the emissions from this in-situ oil fire were less than expected. All compounds and parameters measured more than about 150 meters from the fire were below occupational health exposure levels; very little was detected beyond 500 meters. Pollutants were found to be at lower values in the Newfoundland offshore burn than they were in previous pan tests.

Polyaromatic hydrocarbons (PAHs) were found to be lower in the soot than in the starting oil and were consumed by the fire to a large degree. Particulates in the air were measured by several means and found to be of concern only up to 150 meters downwind at sea level. Combustion gases including carbon dioxide, sulphur dioxide, and carbon monoxide did not reach levels of concern. Volatile organic compounds (VOCs) were abundant, however their concentrations were less than emitted from the nonburning spill.

Over 50 compounds were quantified, several at levels of concern up to 150 meters downwind. Water under the burns was analyzed; no compounds of concern could be found at the detection level of the methods employed. Toxicity tests performed on this water did not show any adverse effect. The burn residue was analyzed for the same compounds as the air samples. Overall, indications from these burn trials are that 150 meters or farther from the burn source emissions from in-situ burning are lower than
health criteria levels.

No comments:

Post a Comment