To clean up an oil spill, first you have to see it. New technology may help.
Finding oil after a serious spill depends on the ability to see the oil in the first place. Whilst a range of technologies are currently being deployed or tested, the hunt is still on for a definite method of identifying oil, rather than water, after a spill.
In the Deepwater Horizon spill, the primary method for detection involved satellite-mounted synthetic-aperture radar (SAR). This technology, which can see through clouds and in the dark, involves bouncing radio waves from orbiting satellites off the surface of the sea.
Oddly, the phrase "pouring oil on troubled waters" helps to explain why it can be difficult to find an oil spill - the waves are calmed by the oil and it then becomes almost impossible to tell the difference between an oil slick and a patch of calm water. But, with SAR, clean-up teams can at least have some idea of where to start more detailed searches.
Not so in places like the Arctic, where exploration is expanding and a spill could have massive environmental impact. Here floating ice looks just like oil or calm water to a SAR-equipped satellite. However, oil and ice have different temperatures, heat signatures and reflective properties so boats or planes using infra-red (IR) and ultraviolet (UV) scanners can differentiate between smooth water, ice and slicks. Oil deposits differ in thickness - thicker reflect more sunlight and emit less heat than thinner ones.
This year Eni Norge, a subsidiary of Italian oil giant, Eni, equipped its fleet of emergency vessels in the Barents Sea in the Norwegian Arctic with cameras made Aptomar Cameras, a Norwegian company. However, the camera needs a clear line of sight to the oil and Arctic oil spills are likely to result in oil under, rather than on top of the ice. Equally, surface oil could quickly be covered by snow.
The alternative detection technology here is ground-penetrating radar (GPR which uses high-frequency radar signals, emitted either from a sled on the surface of the ice or from a low-flying aircraft, to provide an image of the subsurface. Snow, ice and oil reflect radio waves in different ways, allowing oil spills to be seen beneath the surface. However, GPR has its limitations - one particular complication is the presence of salt in the sea.
Additional technologies for detecting oil in icy water are :
- high-power radar to try to improve the range of conditions in which GPR
- detection systems based on nuclear magnetic resonance (NMR)
- robot submarines, known as autonomous underwater vehicles (AUVs and sonar.
With the task of developing further technologies for identifying oil from a spill still ongoing, there still remains the larger challenge of cleaning up once the oil has been located.