Cleaning Oil Spills
I worked as an engineer in the offshore oil and gas industry for many years and have witnessed terrible disasters such as the Piper Alpha, which was close to home and where several local young men lost their lives.
In other offshore oil and gas incidents such as the recent Deepwater Horizon Disaster, lives were again lost and immense damage was done to the wildlife and also to the livelihoods of people involved in fishing and tourism.
We cannot put a price on workers lives lost in these disasters; their relatives will be compensated for their loss, but the loss of human life is the largest cost.
We can, however, calculate the average cost of cleaning oil spills which include the hidden costs of the loss of people’s livelihoods due to oil pollution.
This is an article on the costs involved in cleaning up oil spills, from offshore oil rigs, ships and land based oil operations.
We begin with a look at the equipment used to contain and disperse the oil slicks, and then examine a recent oil spill, finishing with a table of some of the major oil spills over the last decade.
Equipment and Methods Used to Contain and Clean-up Oil Spills
Companies specializing in cleaning up oil spills are using modern engineering technology, as well as biological methods to combat pollution of the sea and coastline.
The popular equipment and methods used for offshore oil spills are as follows:
- Skimming Ships
These can either mop up the oil using large pads, or the newest one known as ‘whale’ is a converted oil tanker which has vents in its hull at different levels. These allow the oil skim to be sucked up into the cargo tanks where it is separated from the water and then the water is pumped back overboard.
Skimmer ships have also been used with floating booms to brush up and corral oil spills. This oil is then set on fire with the resulting char scooped up for disposal.
- Floating Oil Containment Booms
These are made from oil resistant PVC and are weighted at the bottom to remain in the right orientation when in use. They can be joined together using eyelets at each end of the boom to form a floating barrier, preventing surface oil from moving toward a specific area.
- Oil Boom Fence
This is used to protect shore side wetlands against impregnation by an offshore oil spill. It is made from oil resistant nylon and can be easily attached to the sand/mud high-water line with stakes and joined together to provide an effective barrier.
- Oil Dispersant Spray Systems
These are usually supplied in portable or fixed containers and sprayed over the contaminated area by airplane, tugboat or offshore supply vessels.
Following the application of dispersant, the waves break-up the oil floating on the surface to tiny droplets which are then biodegraded by naturally occurring organisms contained in the seawater.
- Biological Methods
This is a comparatively new method known as bioremediation and was used for the first time on major oil pollution project by the Chinese Authorities to contain the Dalian Yellow Sea oil spill.
The process uses especially created micro–organisms, based on the natural hydrocarbon consuming variety to degrade the oil droplets in the oil slick.
Deepwater Horizon Oil Spill Disaster
On the 20th of April, 2010 there was an explosion followed by fire on the Transocean’s drilling oil rig, Deepwater Horizon operating in the Gulf of Mexico, in which 11 men died.
The cause of the explosion was a ‘blowout’; this is a build-up of pressure in the reservoir which literally blew gas and oil up through the risers onto the deck of the rig where it exploded and set fire to the rig.
There are measures and equipment put in place at the wellhead to prevent this occurrence, namely the blow out preventer (BOP). This component can be as tall as 60’ and weigh 450 tons.
Although it has a selection of integrated so called ‘fail safe’ components, the BOP failed to operate and prevent the disaster.
The drilling rig sank on the 22nd of April, and from the bottom of the sea, 5000 feet below the surface, an oil plume poured crude oil unimpeded into the waters of the Gulf of Mexico.
Evacuation of survivors and search for the missing crew members were put in place, and then measures were taken to stop the flow of oil from the reservoir wellhead. The BOP was still in place and divers along with Remote Operated Vehicles (ROV’s) tried unsuccessfully to operate the annular and hydraulic ram mechanisms which would temporally stop the flow of oil but again these components refused to operate.
Meanwhile an unprecedented oil spill cleanup had commenced that included most of the equipment and methods discussed earlier, the Whale skimming ship being the world’s largest of its kind, scooping up and processing the floating oil. Many smaller skimmer ships belonging to the coastguards were also employed some of these using long booms to skim off the oil then set it on fire, chemical dispersants were also used; these would break the oil slick to droplets that the natural seawater bacteria would decompose.
Ashore volunteers were collecting seabirds and wildlife, taking them to temporary sanctuaries to be de-oiled, fed and cared for until they were safe to be released.
Many thousands of workers were laid-off due to the oil pollution, such as oyster farmers and shrimp harvesters along with those in the tourism industry.
All of these activities add to the cost of the oil spill cleanup; these costs along with the costs of major oil spill cleanups over the last decade are illustrated in a table in the Image section. From this table we can calculate the average costs of oil spill clean ups.
Average costs of the oil spill clean-up for the oil disasters listed in the table work out at $161 Million, this does not include the estimated costs of $12.5 Billion to clean up the Gulf of Mexico, as this is unprecedented and would give a false value.
1. timesonline - Deepwater Horizon Disaster.
2. guardianuk - Deepwater Horizon Disaster diary.