pipelines and transport
The globalized transport network for moving oil, gas, coal, and other fuels is staggeringly large and complex. Every day countless trains, ships, and tanker trucks deliver the fuel that keeps the world economy humming. This transport infrastructure, including hundreds of thousands of miles of pipeline, is vulnerable to accidents and terrorism and is costly in money, energy to maintain, and greenhouse gas emissions.
After the discovery of oil, pipeline transport was quickly adopted as the cheapest delivery method. Pipelines are primarily made of steel, with diameters ranging from a few inches to a few feet, and they are often buried at depths between three and six feet. Oil is pushed through the pipelines by pumping stations—and natural gas by compressor stations—scattered along the route. For natural gas, the United States has more than 300,000 miles of pipeline, 1,400 compressor stations, 11,000 delivery points, 24 hubs, and 400 underground storage facilities. For oil, there are tens of thousands of miles of additional pipeline.
Pipelines are generally considered the safest transport method, although accidents do occur. In 2010, while most public attention was diverted to the Deepwater Horizon oil spill in the Gulf of Mexico, a pipeline in Michigan leaked 800,000 barrels of oil into the local river system. In 2010, a natural gas pipeline exploded in California, killing eight people and creating a crater more than 40 feet deep. However, the biggest regular environmental impact from pipelines is habitat fragmentation: Although much of the pipeline infrastructure is buried, the land cover must remain clear to avoid root obstruction.
Where pipelines are impractical, energy resources are transported by ship, train, or truck. As of 2009, more than one-third of all major shipping vessels in the world were moving oil. Bulk carriers, responsible for coal, grain, iron ore, and other commodities, make up another third. Liquefied natural gas (LNG) vessels account for only 3 percent of all vessels but grew at an annual rate of 11 percent from 2009 to 2010.
Building ships, trains, and trucks requires immense amounts of steel; steel production is a significant source of greenhouse gas emissions. There is also a long history of spills associated with transport, especially oil tankers, which can severely affect regional environments. One can readily find oil-soaked sand on the beaches of Prince William Sound more than two decades after the Exxon Valdez spill. The long-term impacts of the Deepwater Horizon spill are yet to be determined.
The contribution of the energy transport system to climate change is difficult to calculate but as the world shifts from high-energy-content fossil fuels to lower quality forms like tar sands and subbituminous coal, the volume of fuel transported will need to increase proportionally. This will require even more pipelines, ships, trains, and trucks, more fuel to construct and operate them, and will result in more greenhouse gas pollution from the energy sector.