Was your new car built under the sea?

Published: 08 Nov 2013

It’s not quite the amphibious submarine car that most engineers have dreamed of owning/building, but a new ocean-based metal extraction process is improving the traditional vehicles.

Fuel efficiency developed from the depths of the ocean

The US Department of Energy’s (DOE) Pacific Northwest National Laboratory (PNNL) is currently developing a process that will allow a lightweight metal to be extracted from the ocean. The most exciting part of this development is that this extract could help make fuel-efficient transport that is cheaper to build and sell, and will expand the use of magnesium into the general market.

The $2.7m, three-year project is set to advance a new method of extraction that removes naturally occurring magnesium from seawater. The project is being led by the PNNL and was originally from the DOE’s Advanced Research Projects Agency – Energy.

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Demand for lightweight metals such as magnesium is on the rise in a number of industries however the cost can be prohibitive and the production methods consume a lot of energy.

PNNL Laboratory Fellow Pete McGrail and project lead said: ‘We expect our method will be 50 per cent more energy efficient than the United States’ current magnesium production process. This will also decrease carbon emissions and the cost.’

When magnesium is used in alloys, it decreases the weight while providing a substantial increase of strength in parts used for vehicles, airplanes, power generation equipment, industrial processes and buildings. This additional functionality comes at a cost though; it’s around seven times more expensive to produce than the steel that has always been traditionally used.

This new and cheaper production process is also more efficient and should allow for more engineers and designers to utilise lightweight metals, which will ultimately lead to a further $32m in funding for new projects. This will develop the new recycling and processing methods involved with the metal.

Currently brine is subjected to electrolysis to extract the metal from molten salt. ‘Reinventing the magnesium production process so it’s more affordable can also help grow the American magnesium market and decrease U.S. reliance on foreign-made materials,’ McGrail said in a statement.

PNNL uses a titanium-based catalyst that will regenerate an essential chemical that is part of the magnesium generation and extraction process. It will be more efficient, use less energy and the temperatures will be some 600 degrees Celsius cooler at 300 degrees, down from the existing requirement of 900 degrees. With a background in catalyst development, powder metallurgy, molecular simulation, PNNL is perfectly placed to develop the process to its full potential. Data modelling and lab testing will reveal what makes the process work.

The official predictions for the project include halving the cost to less than $1.50 per kilogram and consuming only 25 kilowatt-hours of energy.

The project team plans to develop a prototype system that uses the new process. Commercial-scale magnesium production with the new process is expected to halve the current US production cost. It should cost less than $1.50 and require only 25 kilowatt-hours of energy per kilogram. The new method will utilise a crystallisation process as well as traditional electrolysis.


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