COLUMN-What does looming US-China trade showdown mean for aluminium? Andy Home

(The opinions expressed here are those of the author, a columnist for Reuters. Repeats Thursday's column with no changes to text)

By Andy Home

LONDON, Jan 25 (Reuters) - China is awash with aluminium.

"Illegal" capacity has been closed and smelters in the region around Beijing are, to varying extents, curtailing output to comply with the winter environmental restrictions.

But stocks registered with the Shanghai Futures Exchange (ShFE) continue to build. They surged by 653,411 tonnes last year and were up another 30,000 tonnes at a fresh record high of 783,759 tonnes as of last Friday.

U.S. producer Alcoa told analysts on its Q1 conference call it is forecasting a 1.5-1.7 million tonne surplus in China this year, notwithstanding Beijing's efforts to restrain capacity.

It is also forecasting a bigger deficit of 2.0-2.2 million tonnes in the rest of the world, where visible stocks have been falling for many months.

Inventory registered with the London Metal Exchange (LME) is close to multi-year lows at just 840,000 tonnes, discounting metal awaiting physical load-out.

Unsurprisingly, given such dynamics, the aluminium price in London has been outperforming that in Shanghai.

Equally unsurprisingly, more Chinese aluminium, in the form of semi-manufactured products, has been starting to move through the arbitrage window. December's tally of 390,000 tonnes was the highest since June 2017.

This is how the global aluminium market has historically rebalanced itself, Chinese surplus leaking out as "semis".

TRUMP'S TRADE GUNS

But this year could be very different.

China's aluminium sector has grown hugely over the last decade, its share of global production rising from 25 percent at the start of 2006 to over 50 percent now.

The rest of the world's push-back against this dominance has grown similarly, with the United States taking the lead.

The Barack Obama administration filed a formal complaint to the World Trade Organization (WTO) in its dying days, accusing China of subsidising "certain producers of primary aluminium".

Under the Donald Trump administration, things have accelerated.

Preliminary duties on Chinese imports of foil were imposed in October last year, provoking a furious reaction from China, which has itself complained to the WTO. A final determination by the U.S. Commerce Department is scheduled for Feb. 23.

In November, the Commerce Department took the unusual step of self-initiating an investigation into imports of Chinese aluminium alloy sheet. A formal investigation has just been launched with the blessing of the U.S. International Trade Commission.