Companies want to mine for valuable metals in the sea, but questions about processing have not yet been resolved.

The depths of the oceans contain vast amounts of valuable raw materials: Metal nodules on the seabed contain manganese, copper, nickel, cobalt, and sometimes even rare earth elements. According to estimates, there are sometimes more of these in the ocean than can be mined on land.

The deep sea has therefore recently moved into the center of geopolitics. In April, Donald Trump issued a decree to promote deep-sea mining and issue mining licenses as quickly as possible. The US wants to reduce its dependence on China for critical metals, such as those needed for iPhones, batteries, laptop batteries, and solar panels. With his initiative, Trump is ignoring international law regarding the extraction of raw materials in international waters. Until now, the rule has been that no country would mine the valuable nodules on the seabed unless it was clear whether the ecosystem there would be destroyed.

With this regulation, the US has turned a wait-and-see attitude into a race. Their goal: to be the first to gain access to the metals from the sea. And raw materials companies are particularly benefiting from this.

Several companies have been preparing for mining for years, hoping for billions in revenue . It's still unclear where the metals would be processed so they could be sold—or how.

While techniques for collecting valuable manganese nodules from the seabed do exist, they vary in their approach, some being more efficient and others more environmentally friendly.

Some companies use underwater robots whose gripping arms collect the tubers, aiming to take as little sand and marine life with them as possible. A faster—and more aggressive—solution resembles a vacuum cleaner: A device sucks the tubers into the ship through a pipe; sand, sediment, and debris are drained back into the sea and sink back to the seabed.

The processes are neither particularly expensive nor particularly complex to use. What is missing, however, are processing procedures – the crucial step in monetizing the tubers.

Walter Sognnes worked in the Norwegian oil business for 20 years before founding the deep-sea mining company Loke. He says most extraction techniques can be adapted from offshore oil production, and that's not the problem: "Currently, one of the biggest challenges for deep-sea mining companies is processing."

Before the metals could be sold in the future, they would have to be extracted from the manganese nodules and processed to achieve a certain degree of purity.

Processing the nodules is technically challenging. Suitable factories would first have to be built. Deep-sea mining companies are unwilling to take on the task themselves, lacking the necessary expertise. Furthermore, many struggle with the inability to attract sufficient investment. The companies therefore focus on collecting the nodules. They need partner companies that are willing not only to purchase the nodules from them, but also to build the infrastructure for processing them.

Christoph Heinrich is Professor Emeritus of Mineral Resources at the Institute of Geochemistry and Petrology at ETH Zurich. He says: "Cobalt, manganese, copper, nickel, and the rare earths: all of these elements are scattered throughout the nodules in nano- to microcrystalline forms." The metals are thus distributed in tiny quantities. Therefore, according to Heinrich, they can only be extracted through complex chemical processes.

These processes carry their risks. Currently, there are two processes in industrial chemistry to

The first uses heat to melt the tubers in blast furnaces to extract the required raw materials.

This process is already established in industry and is used in steel production, for example. It could also be applied to nodules. This explains why the Canadian company The Metals Company (TMC) has chosen this method. The company is considered a pioneer in deep-sea mining. TMC lobbied Trump for the decree and applied for a mining license from the relevant American authority at the end of April. In February, the company announced that it had smelted the metals contained in the first manganese nodules with the Japanese company Pamco.

But according to a scientific study, the smelting process has two drawbacks: The furnaces require large amounts of energy and emit large amounts of _CO2 . Furthermore, only a certain percentage of the metals can be extracted from the nodules; the rest is lost.

Hans Smit is CEO of the American deep-sea mining company Ocean Minerals, which plans to mine manganese nodules in the sea around the Cook Islands. He says that existing factories can currently only extract 60 to 70 percent of the metals from the nodules using the smelting process. For this reason, and because of the high energy consumption, his company has opted for a different method: dissolving the metals with acid.

This process uses chemicals, which is why complex safety standards apply and expensive wastewater treatment would have to be used.

Although the acid method is also well known in the metals industry, and the chemical processes for the individual metals are established, they are not yet applicable to nodules. According to Smit, a processing plant would first have to combine the processes in a multi-step procedure, extracting the various metals in the correct sequence using the right chemical additives.

Such a factory has to be built first. Smit has developed and documented the complex process. He is currently taking his plans from processor to processor. His hope is to convince companies that it's worthwhile to build factories – since the processing recipe has already been developed and the hurdles are therefore smaller than expected. And yet, it could take years before the first production facilities are built.

Walter Sognnes says that processing is the largest cost factor in the deep-sea mining business. Hans Smit estimates that a factory would cost over $2 billion to build.

Many companies can't wait much longer. They need money and have to stall their investors with promises until potential revenues start flowing in the future.

Deep-sea mining entrepreneur Sognnes says his company originally planned to start large-scale production by 2031—assuming they had received permission to mine by then. Sognnes speaks of 10,000 tons of dry weight of nodules per day, or 3 million tons per year. That was the hope, anyway. However, his company went bankrupt in April.

Hans Smit also has big plans. He wants to harvest tubers with a dry weight of 2 million tons annually and hopes to start in three years. But his project also depends on the construction of the factories and investor funding.

The promises are great, but so are the uncertainties. For Sognnes, the funding wasn't sufficient.

Companies are currently taking advantage of the US attention to hype the economic promise surrounding the nodules. Companies are portraying them as a prerequisite for the energy transition, and Trump needs them in his geopolitical competition with China. But will these metals really be needed on the scale suggested?

According to estimates by the International Energy Agency (IEA), yes, at least in the medium term. Geochemist Heinrich confirms this. The most important battery types will continue to depend on lithium, manganese, nickel, and cobalt for some time to come. But Heinrich also says: "All it takes is the development of a new battery type, and the metals will lose value."

However, the technical questions, legal uncertainties, and uncertain market prospects are not the only hurdles facing companies. Potential environmental risks also exist. Deep-sea mining has been controversial for years. Several countries, including Switzerland and Germany, have initially spoken out against it. Environmentalists and researchers fear that the ocean could suffer irreversible damage.

Smit says he would stop immediately if it turned out that mining would cause too much environmental damage and, for example, contribute to the extinction of animals.

That's what he always tells his investors: "There's a risk that you'll lose everything. But you could also win a lot because you were there from the beginning."