Over a decade on from the Deepwater Horizon oil spill, could we do a better job at cleaning it up today?

On April 20, 2010, a blowout caused a huge explosion on the offshore drilling rig operated by BP in the Gulf of Mexico. Eleven people were killed. Two days later, the rig collapsed. Oil began seeping into the sea, and it continued to flow for almost three months.
The Deepwater Horizon disaster is among the most lamented environmental catastrophes of the past century. It’s hard to comprehend how incredibly huge the spill was. It was the world’s largest ever marine oil spill, releasing an estimated 4.9 million barrels of crude oil (779 million litres, or over 300 Olympic swimming pools-worth). Up to a million seabirds were killed outright, and the human health and socioeconomic effects are still being felt today.
BP, rig operator Transocean, and several government agencies immediately tried to limit the damage, with BPs chief executive saying the company was “determined to do everything in our power” to contain the spill. Booms were deployed to try to contain the oil, skimmer ships nibbled at the edges of the widening slick and fires were set to try to burn it off the sea surface. Various devices were deployed deep below the surface to try to contain or capture the oil. BP also began to spray the oil with enormous amounts of dispersants both on the sea surface and 1.5km (0.9 miles) underwater, where oil was gushing from the wellhead.
However, it is thought that these measures recovered or dispersed only around a third of the spilled oil. The BP spill sparked a huge amount of research into oil spills and their impacts. But 14 years on, what hope is there for better measures should another oil spill occur?

I knew immediately that this would be ecologically and economically disastrous – Jeffrey Short
Jeffrey Short, an expert in oil spills and now-retired scientist from the US National Oceanic and Atmospheric Administration (Noaa), was working for Oceana, a marine conservation organisation when the BP spill occurred. When a colleague told him about the spill at lunchtime, he felt sick.
“I knew immediately that this would be ecologically and economically disastrous, that it would wreck tens of thousands of people’s lives, and that it would dominate my professional life for the next several years,” he says. “All of which proved true.”
Oil spills are the third largest source of oil in the sea, after land-based runoff (largely from cities and vehicles) and natural oil seeps. The problem with spills, of course, is the sheer volume of oil that enters the sea all at once. This means that oil spills – especially big ones – are “much, much more dangerous per unit oil released”, says Short.
While no spill has since surpassed Deepwater Horizon’s in sheer volume, Noaa responds to more than 150 oil spills every year. Just last month, oil began spewing from a submerged oil tanker and at least two other sunken vessels in Manila Bay, in the Philippines, after they were hit by monsoon rains and Typhoon Gaemi. Another oil tanker hit by projectiles from Yemen’s Houthi movement remains in a precarious position in the Red Sea. However, the number of oil spills from tankers is today far lower than in the 1970s, due to improved standards.

When oil spills occur, the first step is to control the source, “whether that be a ship, pipeline, or leaking well”, says Doug Helton, regional supervisor of the emergency response division at Noaa’s Office of Recovery and Restoration. “The second priority is recovering oil at sea.”
The major priority is to avoid the oil reaching the shoreline, where it can do the most damage. Shoreline cleanups can last days to years, depending on the type of oil and severity of contamination, says Helton.
Spilt oil tends to spread quickly into a thin layer on the sea surface. Within days, centimetres-thick layers become a film of a millimetre or less, spread in drifting patches over a wide area. Efforts to scoop up the oil from the sea surface therefore offer diminishing returns as time goes on. “Floating oil spreads very quickly and there is a limited window of time – days – when at-sea tools are effective,” says Helton.
Getty Images Workers attempt to clean up an oil-contaminated beach in Grand Isle, Louisiana, June, 2010 (Credit: Getty Images)Getty Images
Workers attempt to clean up an oil-contaminated beach in Grand Isle, Louisiana, June, 2010 (Credit: Getty Images)
Hundreds of skimmers were deployed to clean up the BP Deep Horizon spill. Skimmers are boats that scoop up spilled oil from the water’s surface, usually after the slick is first surrounded with floating booms to keep it from spreading. They do this in various ways – some, for example, suck up the oil like a vacuum cleaner, while others use oil-attracting “conveyor belts” or gravity to carry the spilled oil into a reservoir.

But hopes at the time that the skimmers could pick up oil “like a lawnmower cutting grass” proved to be overblown. They only recovered an estimated 3% of the oil. “At sea, the oil may spread more rapidly than the skimming vessels trying to capture oil,” says Helton. “Going faster is not an easy option because the bow wave from the ship will push the oil away.”
The satellite photos of the BP disaster “speak volumes”, says Short. “You’ll see a half a dozen surface skimming boats that, from the sea surface next to the boat, look quite large and quite effective. But from a satellite, you realise that you are […] just having a nearly negligible effect on the size of the spill.”
In fact, a 2020 review of 30 large offshore oil spills found only 2-6% of oil was recovered using mechanical methods like skimmers. Short says that mechanical recovery has improved in recent decades, with better booms to corral the oil and better systems to remove it from the sea surface. But even with improvements, mechanical methods can’t have much impact on a large spill, he says.
In recent years a plethora of studies and reports have emerged looking at different ways to soak up oil spills, from laser-treated cork and textiles based on leaves to graphene, magnets and even hair and fur. These mostly rely on the oil-attracting and water-hating properties of the material, with various forms of oil-attracting sponges a particularly common solution. But the difficulty of handling oil-soaked materials means these techniques are typically only useful for small spills.