Some big things going on down below

Norway’s state owned petroleum company Statoil is installing “world’s biggest offshore machine” in the North Sea. It is a seafloor mounted compressor designed to pressurize low yielding oil and gas deposits to wring out more product. The premise of deploying a seafloor installation over surface mounted equipment is that it will save the energy of overcoming 300 meters of water pressure just to get to the wellheads.

This device, like the many other “subsea” installations being built worldwide will be tended by Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs) or “robots” that will manipulate hoses, valves, connectors, and execute other control and maintenance operations. The ROVs are controlled and powered by way of umbilical cables. The AUVs are controlled by acoustic modems – typically in the 10kHz – 80kHz frequency range.

Statoil Seafloor Compressor

Norwegian conservation organizations are wondering why their government is putting state resources toward extending fossil fuel extraction capabilities when they should be focusing on renewable and non-CO2 generating energy sources.

Another question they might want to ask is “how loud will this installation be?” While there are no published numbers on this equipment that I am aware of, the workings of a gargantuan compressor strikes me as something that would not be “whisper quiet.” Adding to this the high frequency acoustic communication channels of the AUVs overlaps the bio-sonar frequency ranges of odontocetes (beaked whales, porpoises, and dolphins) and the hearing ranges of some of their prey (herring for example).

It remains to be seen what impact this equipment will have on marine life. In the US under the Marine Mammal Protection Act the mitigation threshold for continuous noise exposure is 120dB (re: 1µPa). My suspicions are that this compressor and its environs will generate at least that much noise.

It would be ironic if an industry-friendly environmental policy of the US is more conservative than the industrial practices of Norway, where there is a typically a greater public concern for the environment.