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Are magnets and nanotechnology the answer to clean-ups?

07th November 2012

As oil operators venture into deeper and harsher waters, the importance of a vigorous oil spill response plan or immediately deployable clean-up techniques has never been more pressing. This article explores the promising new technologies in development that could prove critical with dealing with small to large-scale accidents.

Are magnets and nanotechnology the answer to clean-ups?
The costs of cleaning up oil spills can run into billions of dollars

Memories of 2010’s fatal Deepwater Horizon disaster serve as a stark reminder of the consequences of human error and the importance of failsafe technology. The clean-up costs have been so astronomical for BP the UK oil giant has been forced to sell its assets in older smaller fields in the gulf to Plains Exploration & Production of Houston to recover costs. Analysts calculate that BP faces a fine of up to USD 20bn under the clean water act for the Deepwater Horizon disaster. Since this catastrophe anda string of other – smaller – incidents, both industry and government has ramped up efforts to ensure with help new technology, along with greater scrutiny, this type of disaster never happens again.

In June US Senator Maria Cantwell, for example, introduced legislation to jumpstart research and development into new oil spill response technology, “bringing oil spill response into the 21st century”. Her bill – the Oil Spill Research and Technology Act of 2012 – hopes to create grants to support the research and development of new technologies to better contain and clean up all types of oil spills. In addition, the bill requires the US Coast Guard to establish a program to evaluate and implement ‘best available technology’ to effectively respond to and clean up oil spills.

“Oil spills pose a great threat to Washington’s economy and the fragile coastlines we all cherish,” said Cantwell. “We must do everything we can to prevent a spill, but if one happens we need to have the best technology on hand to minimise the damage. It’s time to bring the technology we use to clean up oil spills into the 21st century. This bill will help protect our growing coastal economy from the threat of oil spills,” she said.

According to the Washington State Department of Ecology, a major spill would have a significant impact on Washington state’s coastal economy, which employs 165,000 people and generates USD 10.8 billion in annual economic activity. A spill would also severely hurt the state’s export dependent economy because international shipping would likely be severely restricted. Washington state’s waters support a huge variety of fish, shellfish, seabirds, marine mammals, and plants, including a number of Endangered Species Act-protected species such as Southern Resident orcas and Chinook salmon.

US federal regulators also this year gave offshore drilling operators the most specific instructions yet for how companies should prove they are ready to respond to oil spills. A 41-page “notice to lessees” issued was issued earlier by the Bureau of Safety and Environmental Enforcement (BSEE). The document outlines standards for the oil spill response plans that are required of companies drilling on the nation’s outer continental shelf. The plans document exactly what resources companies have to respond to spills from their offshore operations, including exploratory drilling as well as producing wells.

“The Deepwater Horizon response made it clear that existing oil spill response plans were not up to the task of containing and cleaning up a massive offshore blowout,” BSEE Director James A. Watson said in a statement. “We have been using our existing authority to require more robust plans for some time now, and this NTL clarifies that approach for the industry and the public. It will assist industry in preparing response plans that will provide for a rapid, effective response to a worst case scenario.”

Magnetism

Researchers from the Massachusetts Institute of Technology (MIT) have developed a new technique for magnetically separating oil and water that could be used to clean up oil spills. They believe that, with their technique, the oil could be recovered for use, offsetting much of the cost of cleanup.

In the MIT researchers’ scheme, water-repellent ferrous nanoparticles would be mixed with the oil, which could then be separated from the water using magnets. The researchers envision that the process would take place aboard an oil-recovery vessel, to prevent the nanoparticles from contaminating the environment. Afterwards, the nanoparticles could be magnetically removed from the oil and reused.

This approach can work if the concentration of the ferrofluid is known in advance and remains constant. But in water contaminated by an oil spill, the concentration can vary widely. If the oil concentration were zero, the water would naturally flow down both branches. By the same token, if the oil concentration is low, a lot of the water will end up flowing down the branch intended for the oil; if the oil concentration is high, a lot of the oil will end up flowing down the branch intended for the water.

In their experiments, the MIT researchers used a special configuration of magnets, called a Halbach array, to extract the oil from the tops of the cylindrical magnets. When attached to the cylinders, the Halbach array looks kind of like a model-train boxcar mounted on pilings. The magnets in a Halbach array are arranged so that on one side of the array, the magnetic field is close to zero, but on the other side, it’s roughly doubled. In the researchers’ experiments, the oil in the reservoir wasn’t attracted to the bottom of the array, but the top of the array pulled the oil off of the cylindrical magnets.

Microsubmarines

Tiny submarines that are 10 times smaller than the width of a human hair could also be used to clean up oil spills. US researchers have designed self-propelled microsubmarines which can gather oil droplets and take them to collection facilities.
The team from the University of California San Diego's nano-engineering department said their tests showed "great promise".

The research, which appeared in the journal ACS Nano earlier this year, suggested that the microsubmarines were capable of "a facile, rapid and highly efficient collection" of motor and olive oil droplets. The tiny motors are propelled by bubbles created from internal oxidation of hydrogen peroxide. This means they require small amounts of fuel and can move very quickly. Although currently just a lab-based proof of concept, it gives hope to improved methods of dealing with future spill disasters - a requirement made more pressing following painstaking attempts to deal with spills in the Gulf of Mexico

Nanotechnology

Research this month published in the journal Nature Scientific Reports said a new type of nanotechnology could be key to cleaning up oil spills. Scientists this year developed a carbon nanotube sponge capable of soaking up oil in water with unparalleled efficiency with help from computational simulations performed at the Department of Energy’s (DOE’s) Oak Ridge National Laboratory.

Carbon nanotubes, which consist of atom-thick sheets of carbon rolled into cylinders, have captured scientific attention in recent decades because of their high strength, potential high conductivity and light weight. But producing nanotubes in bulk for specialised applications was often limited by difficulties in controlling the growth process as well as dispersing and sorting the produced nanotubes.

According to one of the lead authors, the new blocks are both 'superhydrophobic,' meaning they do not absorb water and thus can float, while also being 'oleophilic,' which means that they can absorb vast amounts of oil. The carbon blocks can hold up to 123 times their weight in oil.
 
"Our goal was to find a way to make three-dimensional networks of these carbon nanotubes that would form a macroscale fabric — a spongy block of nanotubes that would be big and thick enough to be used to clean up oil spills and to perform other tasks," wrote Mauricio Terrones, a professor of physics, materials science and engineering at Penn State and the study’s co-author, according to Science Daily.
 
The sponges are also said to conduct electricity, allowing them to be controlled by magnets. Researchers believe that the sponges can be created much larger than those tested and be used to clean up major oil spills in the future.

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