Introduction
Advances in exploration and production have helped to locate and recover a supply of oil and natural gas from major reserves across the globe. At the same time, demand for petroleum-based products has grown in every corner of the world. But supply and demand are rarely concentrated in the same place. Transportation therefore is vital to ensuring the reliable and affordable flow of petroleum we all count on to fuel our cars, heat our homes and improve the quality of our lives.
Tankers and pipelines are proven, efficient and economical means of connecting petroleum supply and demand. Supply-end pipelines carry crude oil from well to a loading terminal at a port. Tankers then carry the crude oil directly to demand-side pipelines that connect to the refineries that convert the raw material into useful products. Select the dates at left to see how the shipping of crude oil has evolved over time into the high-tech, reliable and environmentally sound system we enjoy today.
1885 - The United States and Russia were the major producers of crude oil, most of which was refined into kerosene. Invented in 1854, kerosene was in demand because it burned cleaner and brighter than other lamp fuels, such as whale oil. Kerosene from American refineries was soon crossing the Atlantic to meet growing demand in Europe.
The first oil exports crossed the ocean aboard all-purpose sailing ships, stored in the same wooden barrels usually used for wine.
Some of these ships were later outfitted with large-volume tanks to increase their carrying capacity.
Eventually, ships were built specifically to carry oil and petroleum products. The Glückauf, launched in 1886 and featuring an extra-strong hull, reinforced construction and specialized oil-handling systems, is considered the forerunner of modern oil tankers.
1955 - The automobile revolutionized American life in the first half of the 20th Century and created increased demand for gasoline. Oil also helped power rebuilding efforts after two destructive world wars. To ensure adequate supply to meet the growing demand, exploration and recovery efforts focused on new sources in the Middle East and Canada.
The need to deliver more oil called for larger tankers. Early iron and steel vessels were built using the same principles as wooden sailing ships -- lateral framing pieces attached to a single keel -- but problems with weight distribution and structural rigidity limited tankers to 82,000-barrel capacity. In 1908, Sir Joseph Isherwood patented a new shipbuilding technique that included frames and bulkheads running front-to-back and used the ship's floors to increase rigidity. By the early 1950's, "supertankers" built using a modified version of Isherwood's system had capacities of more than 280,000 barrels.
2002 - In the latter half of the 20th Century, advances in exploration and recovery technology opened up new supplies of oil and natural gas all around the world. To make long-distance transportation more cost-effective, tanker manufacturers developed "very large capacity carriers," or VLCCs, that can carry more than 1,400,000 barrels of crude oil.
Larger tankers conserve energy and reduce transportation costs. That's because although it requires more energy to power a larger ship, the rate of increase is less than the rate of increase in carrying capacity. For example, 16,000 horsepower are needed to drive a 420,000-barrel tanker, while 42,500 horsepower can propel a 1,820,000-barrel ship at the same speed. That means it takes less than three times the power to deliver more than four times the oil, reducing total energy consumption and saving fuel.
Tanker Design
Today's cutting-edge tankers are the product of a commitment to safety combined with the power of computer-assisted design. As a result, the new ships traveling the seas are stronger, more maneuverable, and more durable than their predecessors.
Double Hulls - By 2015, all tankers operating in U.S. waters will be double-hulled vessels. This hull-within-a-hull configuration provides an extra measure of security: In the unlikely event of a collision or grounding, the outer hull will bear the brunt of the impact while the interior hull keeps the cargo secure and prevents oil from entering the marine environment.
Redundant Systems - In an effort to build ships capable of withstanding even the most extreme circumstances, many tankers are now equipped with redundant, or duplicate, systems. If the original system is compromised for whatever reason, a second, fully functional backup is on hand. This concept is put to use in navigation -- with back-up GPS systems, for example -- and down below in redundant engine rooms. Duplicate rudders and propellers have the added benefit of improved maneuverability, enabling the ship to rotate 360° in a fixed position.
Single-Operator Capability - A highly trained bridge crew is the key to effective decision-making on the seas. Once a decision is made, however, modern tankers allow a single deck officer to make all the appropriate adjustments to the ship's speed and heading from a central command station. This allows for faster response in critical situations.
Navigation
Before they can be certified to pilot a tanker, deck officer candidates must spend hours in sophisticated bridge simulators gaining hands-on experience with today's state-of-the-art navigation systems, including:
Electronic Chart Display (ECDIS)
Automated Radar Plotting Aid (ARPA)
Automatic Identification Systems (AIS)
ECDIS - The electronic chart display and information system (ECDIS) contains detailed maps of the route, including water depths, underwater hazards and port configurations. Information from a satellite-based global positioning system (GPS) plots the ship's location on the map. Data from the helm feeds automatically into the ECDIS computer, which displays both the ship's heading (where the bow is pointed) and its actual movement through the water. Deck officers can then see clearly if winds or currents are affecting the ship's course. An alarm will sound if the ship drifts off of its pre-set course.
ARPA - Today's radar has the power of computers behind it. Automated radar plotting aided technology (ARPA) not only locates objects within radar range, but also calculates the speed and course of any moving objects. This information, which can be fed into the ECDIS screen, can be used to project the object's relative vector - its movement relative to the ship if both continue at their current speed and heading.
AIS - Ships large and small now feature advanced radio beacons, called automatic identification systems (AIS) that broadcast their identity, course, speed and position. A tanker captain can use the system to identify all vessels in surrounding waters and establish radio communications with those ships as needed.
Lightering
Large-scale transportation of crude oil helps conserve energy and reduce costs over long distances, but many large tankers can't access U.S. ports when fully loaded because their draft - the distance from the water line to the bottom of the boat - is too deep. Lightering - transferring crude oil from supertankers to smaller tankers capable of navigating our waterways - is a simple but effective solution to the problem. More than 25 percent of the 7.5 million barrels of crude oil imported to the United States every day is lightered, mostly in the Gulf of Mexico and along the East Coast.
Lightering can take place either underway at sea or at anchor. Rubber fenders are placed over the ships' sides to prevent damage to their hulls. Crude is offloaded through flexible pipelines from the larger ("mother") ship to the smaller ("daughter") tanker or barge. The daughter ships can then offload their oil cargo at the nearest port or at more distant locations, as markets demand. In some cases, the mother tanker can also proceed to port once sufficient crude has been off-loaded to reduce the ship's draft.
For example, fully loaded Suezmax tankers enter the Delaware Bay with a draft of 55 feet and are lightered to less than 40 feet. The lightered tankers can then proceed to refineries located up the Delaware River.
Louisiana Offshore Oil Port
The Louisiana Offshore Oil Port (LOOP) is another innovative solution to the problem of supertanker size. This revolutionary offshore facility allows supertankers to transfer their cargoes of crude oil directly into a pipeline network reaching more than 50 percent of U.S. refinery capacity - all without leaving the safety of deep Gulf waters.
Located 18 miles off the coast of Louisiana, where the water is approximately 115 feet deep, LOOP features three separate mooring stations anchored to the ocean floor and connected to an underwater pipeline system. The modular design means that up to three supertankers can unload their cargo of oil at the same time.
Mooring - Flexible hoses at the mooring station carry crude oil from the tanker into the underwater pipeline. The mooring buoy and hoses can rotate through 360 degrees, allowing the tanker to maintain a favorable heading into the wind and waves throughout the unloading process. All LOOP operations are monitored from the state-of-the-art central control platform.
Pumping - Two sets of four diesel-powered pumps - one on the offshore platform, the other where the underwater pipeline comes aground - keep the crude oil flowing at a rate of more than 100,000 barrels per hour. The pumps work like an electric fan: The diesel engines spin rotors that create suction like the blades of a fan. Crude oil is drawn from the line coming in from the mooring stations and forced through the outgoing line, headed toward the storage facility.
Storage - Oil gathered at the LOOP facility is stored in underground caverns carved out of a salt dome millions of years old. This geologic formation is ideal because the oil can neither dissolve nor move through the cavern walls. Each cavern is a closed system because what volume isn't filled with oil is filled with brine (i.e. salt water). Since crude oil is less dense than brine, it floats on top. Pumping oil from the offshore pipeline into the cavern forces brine up through pipes at the bottom and into surface reservoirs. When it's time to send the oil to the refinery, brine is pumped back into the bottom of the cavern, pushing the oil out through pipes at the top.
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