Anglesey Aluminium Metal Ltd was a joint venture between the British-Australian mining company Rio Tinto and the American firm Kaiser Aluminum. The smelter was built on the Penrhos Estate -- 500 acres sold by the Stanley family of Penrhos Hall for the project -- and began producing aluminium in 1971, around the time Wylfa Power Station came on full load. The two facilities were partners. Aluminium smelting requires enormous quantities of cheap, constant electricity to drive the electrolysis that separates the metal from its ore, and a nuclear station needs steady customers to take its base-load output. Anglesey Aluminium took the load. The grid was spared the cost of keeping a backup station on standby for nighttime troughs in demand. By the late 1970s the smelter was producing up to 142,000 tonnes of aluminium a year. Raw materials -- alumina from Jamaica, coke from Australia -- came in by ship to a private jetty in Holyhead harbour, then by underground conveyor belt and spur railway to the plant.

The Wylfa contract was due to expire in 2009. By the mid-2000s, with Wylfa itself approaching the end of its design life, no replacement supply could be secured at a price that would keep the smelter competitive against producers in Iceland and the Gulf. Rio Tinto announced the closure of the smelting operation in January 2009. The last shift ran on 30 September. Five hundred and forty people, most of them long-tenured workers with specialist skills, were out of work in a community where the smelter had been the single largest employer for two generations. Holyhead is not a large town. There was no other industrial employer at that scale anywhere on Anglesey. The shock to the local economy was severe and is still felt. A re-melt facility kept some workers on past the smelter closure, but it was shut down in February 2013. Plans for a biomass plant on the cleared site never came to anything.

For more than a decade the empty plant sat above the western edge of the town, the 450-foot chimney visible from Holyhead Mountain and from the Stena Line ferries pulling into the harbour. The chimney had been a navigation landmark. Sailors approaching the port could pick it out from miles offshore. On 20 March 2024, after the site had been cleared in 2023, the chimney was demolished by controlled explosive collapse. A BBC video crew filmed it falling. The townspeople who watched from the seafront did not all cheer. The chimney was a symbol of an era, and the era had ended badly. In September 2022 it had been announced that the Swedish ferry operator Stena Line had bought the entire smelter site, intending to use it for an expansion of their Holyhead port operations. The sale included the spur rail line, the jetty, and the conveyor tunnel. New industry would come, the announcement said. It is still coming.

Adjacent to the cleared site is Penrhos Country Park, a public-access space on what was once part of the Stanley estate. The Aluminium Powder Company, ALPOCO, still operates near the former smelter, producing aluminium powder for industrial customers in chemicals, metallurgy, pyrotechnics, and spray deposition. ALPOCO's product range is the kind of specialty work that small chemical plants can do without massive electrical loads. It is not the same as a smelter. The 540 jobs are not coming back at that scale. The Wylfa station, the partner that made the smelter possible, was finally shut down for good in December 2015. Plans for a new Wylfa Newydd reactor on the same site have come and gone several times, most recently with a 2024 announcement of renewed interest from the Welsh and UK governments. If the new station is built, it will be looking again for industrial customers to take its base load. The geography of the partnership is still right. The political and economic conditions that made it work the first time are harder to put back together.