A thorough investigation of mineral extraction will allow you to better understand the effects of deep sea mining

The deep sea beds are scattered with ancient rocks, each of the size of closed fists, known as “polymetallic nodules.” Elsewhere, along the boundaries of active, inert hydrothermal holes and deep-sea ridges, volcanic arcs and tectonic plates, the captain’s sides are other types of mineral-rich deposits, including high-demand minerals.

Minerals found in the deep sea are used to manufacture products such as lithium-ion batteries used to power electric vehicles, cell phones and solar cells. In some cases, the estimated resources of important mineral deposits in parts of deep-sea oceans have exceeded the world’s land reserves several times.

“Society wants electric vehicles, solar cells for clean energy, but this all requires resources,” said Thomas Peacock, professor of mechanical engineering at MIT, in a video discussing his research. “Sea resources are depleted or more difficult to access. In some parts of the ocean, there are far more resources than onshore reserves. The question is, wouldn’t mining some of these resources from the ocean rather than from land would have much of an impact?”

Deep sea mining is a new frontier of mineral extraction, with potentially important implications for industry and the global economy, and is a key environmental and social consideration. Through research, scientists like Peacock can objectively and rigorously study the effects of deep-sea mining activities and provide evidence to withstand decision-making.

Mining activities, whether on land or at sea, can have a significant impact on environments on local, regional and global scales. With growing interest in deep-sea mining, demand for critical minerals has skyrocketed, scientific enquiries can help light trade-offs.

Peacock has long studied the potential impacts of deep-sea mining in the Pacific region known as the Polyorion Clipperton Zone (CCZ). Ten years ago, his research group began researching deep sea mining and saw important needs for developing surveillance and modeling capabilities to assess the scale of impacts.

Today, his MIT Environmental Dynamics Laboratory (EndLab) is at the forefront of advancing understanding of new marine use technologies. With research that is fixed to basic fluid dynamics, the team is developing cutting-edge monitoring programs, new sensors and modeling tools.

“We are studying the shape of suspended sediments from deep-sea mining operations, testing new sediment sensors and another new sensor for turbulence, studying early stages of sediment feather development, and analyzing data from the 2021 and 2022 technical tests in the Pacific,” he explains.

In deep-sea nodule mining, the vehicle collects the nodule from the seabed and returns it to the container above. After the critical material is collected in the container, the remaining deposits may be returned to the deep sea column. The resulting sediment plume and its potential impact are key focuses on the team’s work.

A 2022 study conducted at CCZ examined the dynamics of sediment plumes near deep-sea polymorphic nodule mining vehicles. In the experiments, most of the water containing released sediments is between 92-98%, staying near the seabed bed and spreading laterally. The results suggest that the dynamics of the turbidity current set the proportion of sediment that remains suspended in the water, along with the scale of the surrounding sediment plume that follows.

The previously overlooked meaning of the process is important for plume modeling and is beneficial for environmental impact statements.

“The breakthroughs in new models will help you make more and more reliable predictions,” he says. The team also contributed to recent research published in the journal Nature. This study showed that sediments away from the test mining site were presumably cleaned up by ocean currents and reported on observed biological recovery.

Researchers observed the site forty years after the nodule inspection mining experiment. Although biological effects were present in many groups of organisms, populations of several organisms, including sediment macrofauna, mobile deposit feeders, and even large endemic faunas, were beginning to be reestablished despite sustained physical changes at the seabed. This study was led by the National Oceanography Centre in the UK

“We’ve learned a lot about the liquid mechanics of deep-sea mining, especially deep-sea mining sediment plumes,” Peacock said, adding that scientific advances continue to bring more results along the way. This work sets new standards for field monitoring of suspended sediment properties and methods for interpreting field data from recent technical tests.

This story has been republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and education.