The metals world is descending on London for the biggest annual bash in the industry’s calendar, but there’s not much to celebrate.

Going green is the new differentiator in the cut-throat business of making aluminium.

The move comes a week after the miner downplayed its annual aluminium production guidance and flagged challenging conditions in the industry.

Experts say such challenges have the potential to significantly impact the global supply of metals.

The United States was once the world’s biggest producer of primary aluminum. But by the time Trump took office, production had dwindled to the level last seen in 1951.

The largest US aluminum maker outlined its restructuring plans in an earnings statement Wednesday.

Construction on the project, expected to produce 12 million tonnes of the aluminium ore a year, would be completed in the first quarter of 2020.