In the quest for solutions, countries, communities and companies – UC RUSAL, for example – are turning to water for renewable energy, or to develop sea-based solutions.

That's what they've been doing at the University of York with an experiment that uses plentiful sea water, combines it with aluminium waste products, and transforms the CO2 into a solid mineral that's a natural component of the Earth's crust. When the scrap metal is mixed with the sea water in a reactor that's also made from aluminium, it undergoes a chemical reaction that traps the harmful gas culprits.

"We wanted to look for methods of trapping the gas using environmentally friendly tools to produce a result that could be highly scalable to capture millions of tons of unwanted carbon dioxide," says Dr. Michael North, a University of York professor in the Department of Chemistry. North and Dr. Alison Parkin are the lead authors of the sea-scrap metal research published in the ChemSusChem journal.

North's goals are ambitious, but the science on which his team based its experiments is deceptively simple. "We started with the realization that using graphite, the material used in pencils, to line aluminium reactors, results in the mineralization of carbon dioxide," he said. "We wanted to trap the gas at much higher levels, using low-energy processes, so we decided to look at waste materials, such as scrap metals, to see if this could be done without using chemical agents as a catalyst."

So they filled the aluminium reactor with sea water taken from Whitby, along the North Sea coastline in the central part of the country. Then they added aluminium waste – nothing exotic, simply the material used in mountains of kitchen foil and discarded food wrappers. Then the York scientists initiated an electrochemical reaction to see how well the process would work in turning CO2 gas into dawsonite, a mineral with a chemical formula of NaAlCO3(OH)2. Past research on the mineral has looked at ways it might be used to reduce etching stream waste in the aluminium industry, or in CO2 sequestration itself.

What past research also has found is that the process for mineralizing the CO2 was far too expensive and inefficient for it to be taken seriously – as yet – as a possible solution to reducing harmful GHGs. Now the York team says their research shows 850 million tons of CO2 could be turned into dawsonite each year, using sea water, clean-energy solar power and scrap metal that otherwise goes to waste. The process doesn't need high energy gas-pressurization or any toxic chemicals to produce the same effect.

"Tens of millions of tons of waste aluminium are not recycled each year, so why not put this to better use to improve our environment?" asks North. "The aluminium in this process can also be replaced by iron, another product that goes to waste in the millions of tons. Using two of the most abundant metals in the Earth's crust means this process is highly sustainable."

Costs also are lower because hydrogen isn't needed to begin the process, although it is a by-product – adding to the value because it's a nonpolluting, zero-emission gas key to the future production of fuels. The researchers now are working to boost the energy efficiency of the process, and find ways to collect and use the hydrogen too.