Oil Spill Prevention Strategies Resulting From Exxon Valdez Oil Spill
As the most studied oil spill to date and the largest such incident in U.S. waters, the Exxon Valdez oil spill was a major impetus to the Oil Pollution Act of 1990, which established a five-cent per barrel tax on oil to create a $1 billion per spill cleanup fund. Although oil spill accidents represent only 5% of the estimated 700 million gallons of oil entering the seas annually, they dispense a very concentrated dose of oil to the environment when they occur.
The American Petroleum Institute, in acknowledging the futility of dealing with a catastrophic tanker spill, has stated the following: "Further research into recovery technology can certainly help in this regard, but it is not considered likely that we can move to the point of guaranteeing containment and recovery at sea."15 Thus, the emphasis ought to be on oil spill prevention. Notable improvements have been made in the area of prevention as a result of the Exxon Valdez oil spill.
Ship Escort and Response Vessel System (SERVS)
SERVS is a more secure oil transport system that has been implemented by Alyeska at an annual cost of $50 million. This system provides tanker escort for the 60 miles to the ocean entrance to PWS by two vessels, one of which is a 210-foot ship equipped with oil skimmers, containment boom, oil dispersants, and oil storage tanks.16
Marine Spill Response Corporation (MSRC)
U.S. oil companies have created MSRC, which consists of five regional spill centers, any one of which could handle an oil spill of 200,000 barrels. Established at an initial cost of $900 million in 1991, the MSRC plans to spend between $30 and 35 million on research and development of oil spill cleanup technology over a five-year period. It expects to contribute $1 million to $4 million per year thereafter.9
If a normal tanker hull is ruptured, oil is released into the water because the oil pressure exceeds the water pressure. However, in hydrostatic loading the oil would not be released because seawater would exert greater pressure than the oil in the tanker. This differential pressure would result from the incomplete loading of the hull to allow for a compressible air space above the oil. Under the Oil Pollution Act of 1990 double-hulled tankers, which provide a protective space between the outside wall of the vessel and the inner wall of the oil storage tank, will be required by 2015 in all U.S. waters. However, double hulls offer only a partial solution. In a high-impact collision, such as occurred in the Exxon Valdez accident, the accumulation of hydrocarbons in the space between the hulls could increase the likelihood of explosion.14
In the event of a future oil spill, remote-sensing technology may be helpful in locating the thicker region of a slick. Ultraviolet (UV) devices can differentiate between oil and water because the aromatic compounds in oil absorb UV light. While aromatic compounds in oil containing conjugated ¹-bond systems absorb light in the UV range (200-380 nm), water still absorbs more UV radiation than does oil. Infrared (IR) systems can discern differences in sea-surface temperature due to the differences in the physical properties of oil and water. Oil thicker than several thousandths of an inch can sustain a detectable difference in temperature. However, temperatures drop at night with an attendant alteration of the image. A third innovative approach involves a laser fluorosensor. While the oil absorbs light in the UV range, it would fluorescem in the visible spectrum. The unique fluorescense spectrum of the oil would prevent any ambiguity with the spectra of algae or anything else floating on the water. In fact, based on the oil fluorescence spectrum , it is possible to differentiate between diesel fuel, crude oil, and bunker fuel.14