In a 2026 study, scientists found enough lithium and magnesium in just 0.1% of the ocean to last 50,000 years. Now, an Olympic pool of seawater exposes the huge gap between abundance and accessibility

The ocean may look like an almost limitless source of natural resources, but having enormous quantities of a mineral in seawater does not necessarily mean that the material can be collected economically. Researchers are currently analyzing whether existing coastal water flows could become a source of critical minerals while also producing other useful materials.

Researchers at Pacific Northwest National Laboratory (PNNL) estimate that just 0.1% of Earth’s seawater contains enough critical minerals like magnesium and lithium to meet humanity’s needs for 50,000 years or more, assuming those materials could be extracted fully. The finding illustrates a significant distinction between how much of a resource exists and how practical it is to recover.


The challenge is concentration. Valuable elements are spread through huge quantities of seawater at very low levels. Processing enough water to isolate a single trace metal could need substantial amounts of energy, infrastructure, and money. PNNL is therefore investigating connected methods that involve magnesium recovery, desalination brine, and mineral-accumulating seaweed.

What an Olympic Pool of Seawater Reveals

An Olympic-sized pool containing around 600,000 gallons of seawater offers a useful way to visualize the problem. As per the information provided, that volume would contain almost 2,980 kilograms of magnesium, compared with only 0.42 kilograms of lithium and 0.00095 kilograms of nickel.

The nickel quantity is especially striking: it would weigh less than a typical paper clip.

These figures show why seawater mineral recovery cannot simply depend on pumping enormous quantities of water to get one trace element. Seawater chemistry is relatively consistent across the world's oceans, but the concentrations of individual valuable minerals can be extremely low.

For the technology to make practical sense, researchers may require to recover several useful products from the same water stream.

Magnesium Offers an Early Opportunity

PNNL's initial approach focuses on magnesium, which is present in seawater at much higher concentrations than some other critical materials. In a peer-reviewed study, researchers flowed seawater alongside sodium hydroxide, creating a narrow reaction zone where high-purity magnesium hydroxide formed.

A thin solid layer helped limit contamination from calcium. The approach also avoids many purification stages associated with the traditional Dow process. PNNL says the method can eliminate at least four steps.

Desalination Plants Could Provide a Useful Starting Point

Coastal desalination facilities may offer an especially interesting place for this technology because they already manage enormous volumes of seawater.

PNNL modeled California's Carlsbad plant, whose everyday flow is around 108 million gallons. At a theoretical 100% recovery rate, that flow could produce almost 524,000 kilograms of magnesium hydroxide per day, which would be over three times current U.S. use.

That figure should not be interpreted as an expected production level. It features an upper theoretical limit. Actual output would depend on recovery efficiency, electricity requirements, chemical costs, equipment performance, and other practical considerations.

As chemist Chinmayee Subban stated, “the challenge will be to scale up these technologies so they can be economically feasible.”

Turning Desalination Brine Into Another Resource

The mineral-recovery process could possibly be integrated with desalination rather than operating separately. After magnesium removal, seawater can move through reverse osmosis to produce freshwater and concentrated brine.

Researchers are also analyzing bipolar membrane electrodialysis, or BPMED. This technology uses electricity and specialized membranes to divide concentrated brine into acidic and alkaline streams instead of simply treating the brine as waste.

The resulting acidic stream has illustrated another potential application. In a 2026 study, it leached 37% more nickel from olivine containing just 0.27% nickel than equal-strength commercial hydrochloric acid at room temperature. Researchers subsequently recovered a nickel-iron alloy through electroplating.

Seaweed Could Concentrate Minerals Naturally

PNNL is also exploring a biological route to mineral recovery. Some seaweed tissues can contain critical materials at concentrations up to one million times more than in the surrounding seawater, as per the PNNL researchers.

Different seaweed varieties, however, can collect very different combinations of minerals. Researchers are therefore analyzing which species are most promising, how they could be cultivated, and how their accumulated minerals could be released efficiently.

The first benchmark is to recover at least half of the mineral content efficiently, although reaching that goal remains challenging. PNNL's own life-cycle modeling also found seawater pumping as the largest contributor to the climate footprint of its algae-based pathway.

A Different Way to Think About Ocean Resources

The most realistic opportunity may not be substituting conventional mining with seawater extraction overnight. Instead, researchers are investigating whether existing coastal water flows can be used to generate multiple valuable outputs simultaneously.

One integrated system could potentially generate magnesium hydroxide, freshwater, useful acids and bases, nickel from low-grade rock, and mineral-rich biomass.

Such a method could make better use of water that is already being moved through desalination infrastructure while potentially minimizing waste streams.

But substantial testing remains necessary before these concepts can be considered commercially ready. Field deployment, realistic recovery rates, full life-cycle assessments, and monitoring of brine, chemical discharge, seawater intake, and coastal ecosystems will be important in determining whether these technologies can work outside controlled research environments.

The ocean may have an extraordinary mineral inventory, but abundance alone does not solve the problem of accessibility. The real challenge is developing methods that can recover those resources efficiently, affordably, and responsibly. The research from PNNL suggests that the future may lie not in treating seawater as a single source of one mineral, but in finding ways to turn existing coastal water flows into several useful products at once.

Source: ECONEWS

FAQs:

Q1. Why are scientists interested in seawater minerals?

Seawater contains many minerals and elements that could be useful for modern technologies. Researchers are investigating whether these resources can be recovered efficiently.

Q2. What minerals are found in seawater?

Seawater contains minerals and elements including magnesium, lithium, nickel, and other critical materials. Their concentrations vary greatly.