Tankers

Oil Tanker at Al-Basrah Offshore Oil Terminal in Umm Qasr, Persian Gulf. Photo: U.S. Navy. All images from GAO.

U. S. energy needs rest heavily on ship-based imports. Tankers bring 55 percent of the nation’s crude oil supply, as well as liquefied gases and refined products like jet fuel.

These energy commodities require different handling methods, and as a result, various kinds of tankers have been built to accommodate them.

An LNG carrier is designed for transporting LNG at minus 260 degrees Fahrenheit, when gas liquefies and shrinks drastically in volume. The cargo is transported in special tanks insulated to minimize evaporation. LNG carriers are up to 1,000 feet long and have a draft (depth below the water line) of 40 feet when fully loaded.

The global LNG fleet is expected to double from 200 in 2006 to over 400 by 2010. According to industry reports, the existing fleet has completed more than 33,000 voyages without a substantial spill.

Oil tankers are more numerous and vary greatly in size. Tankers transporting crude oil from the Middle East generally consist of Very Large Crude Carriers, which typically carry more than 2 million barrels of oil per voyage. These ships are over 1,000 feet long, nearly 200 feet wide, and have a draft of over 65 feet (pictured above).

These ships are too big for most U.S. ports and must transfer their loads to smaller tankers (a process called lightering) or unload at an offshore terminal.

At present, the United States has only one such offshore terminal—the Louisiana Offshore Oil Port (LOOP). LOOP, the only U.S. deepwater oil port that can handle fully loaded Very Large Crude Carriers, is located 18 miles off the Louisiana coast and currently handles about 10 percent of U.S. crude oil imports.

Most tankers transporting cargos from the Caribbean and South America, by contrast, are smaller than Very Large Crude Carriers and can enter U.S. ports directly.

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Tanker with Insert of Double Hull. - Click to enlarge image.

The Oil Pollution Act of 1990 requires that all tankers built after 1994 coming to the United States must have double hulls—that is, a two-layered hull to help prevent spills resulting from a collision or grounding.

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According to the Energy Information Administration, the United States consumes more than 20 million barrels of petroleum every day. Of that amount, over 65 percent comes from foreign sources.

The top suppliers of crude oil and petroleum products to the United States in 2005 were Canada, Mexico, Saudi Arabia, Venezuela, and Nigeria—each supplying over 1 million barrels of petroleum per day.

Top Exporters of Petroleum to the United States in 2005 (Millions of barrels per day.)

Iraq, Algeria, Angola, Russia, and the United Kingdom are also major energy suppliers with daily imports to the United States of up to 500,000 barrels per day. These top 10 energy suppliers accounted for approximately 75 percent of all U.S. petroleum imports in 2005.

All petroleum imports to the United States from those countries arrive on tankers, except those from Canada.

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Tanker Limburg after Terrorist Attack near Yemen.

Attacks overseas show that tankers face several major types of threats that, if carried out domestically, could have serious consequences. Overseas, terrorists have demonstrated the ability to carry out at least three main types of threats.

First—and overall of greatest concern to officials the GAO spoke with—is a suicide attack, such as the 2002 suicide boat attack on the tanker Limburg off the coast of Yemen. This attack killed 1 person, injured 17, and spilled 90,000 barrels of oil.

A second major type of threat, known as a "standoff attack," uses a rocket or other weapon launched at a sufficient distance to allow the attackers to evade defensive fire.

A third type of threat is an armed assault. For example, well-armed bands have used small boats to attack tankers, loading facilities, and oil workers.

Many other types of potential attacks exist, such as internal crew conspiracies and collisions with other vessels piloted by terrorists.

To date, no such attacks have occurred on tankers in U.S. waters or on loading facilities in U.S. ports, and intelligence officials report there is currently no specific credible threat to tankers or terminals on the domestic front.

Nonetheless, these successful attacks abroad, the expressed desire by terrorists to target U.S. economic interests, and the potential outcome of a terrorist attack on a tanker have led Congress and the Administration to conclude that protective efforts are warranted.

A successful attack on an energy commodity tanker could have substantial public safety, environmental, and economic consequences.

Public safety and environmental consequences of an attack vary by commodity.

For instance, highly combustible commodities like LNG and LPG have the potential to catch fire, or in a more unlikely scenario—if they are trapped in a confined space such as under a dock—explode, posing a threat to public safety.

Crude oil and heavy petroleum products remain in the environment after they are spilled and must be removed, potentially causing significant environmental damage.

Finally, the economic consequences of a major attack could include a temporary price spike reflecting fears of further attacks, and supply disruptions associated with delays of shipments if major transit routes, key facilities, or key ports are closed.

The loss of one cargo of an energy commodity might not have a significant, sustained price impact. However, if an attack results in port closures for multiple days or weeks, price responses and higher costs could mean losses in economic welfare to consumers, businesses, and government amounting to billions of dollars.

Navies of various countries, including the United States, are patrolling threatened waters, such as the Persian Gulf and the Gulf of Aden, due to attacks on ships, including tankers, and port facilities.

Much security remains to be implemented.

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Source: Report to Congressional Requesters, United States Government Accountability Office (GAO). MARITIME SECURITY: Federal Efforts Needed to Address Challenges in Preventing and Responding to Terrorist Attacks on Energy Commodity Tankers. (PDF 4.77 MB)