Australians Cate Blanchett and wildlife conservationist Robert Irwin have walked a green carpet with the Prince of Wales at the annual Earthshot Prize ceremony in Singapore.

Five green innovators were awarded £1 million ($1.9 million) each for their work on projects including a cleaner lithium-ion battery and ocean conservation.

Tasmanian company Sea Forest was among the 15 finalists, but missed out on the top prize, for its seaweed product that can be fed to cows to stop them from burping the pollutant gas methane.

“The light of optimism is burning bright in our Earthshot finalists,” Prince William said at the ceremony in Singapore.

The prince rewore a dark green velvet Alexander McQueen blazer for Tuesday’s ceremony.

Blanchett, who is a member of the Earthshot Prize’s council, donned a gold brocade suit from Stella McCartney’s spring 2024 collection. The brand claims it was “crafted from 95 percent responsible materials” that included yarn made from seaweed, recycled glass, repurposed silk, organic cottons, and vegan leathers crafted from the byproduct of grapes used to produce champagne.

Irwin, a presenter on the night and recently named as the new co-host of I’m A Celebrity…Get Me Out Of Here!, praised William as a “real beacon to everyone in the conservation field”.

“It’s hard to put into words just how massive Earthshot is for wildlife conservation, for climate action, for the world,” he told People magazine.

“For Prince William who has such a great platform, to lend his voice, his resources into creating positive change is such a refreshing, wonderful thing to see”

Irwin, who was in Singapore with his girlfriend Rorie Buckey, said he was an admirer of the Prince of Wales.

“He is certainly someone I look up to and I hope I can create the same sort of change that he does. He is a real beacon to everyone in the conservation field,” he said.

The young couple beamed for photos in dapper evening wear, with Robert sporting a classic suit and tie. Buckey wore a floral gown with cutouts.

This year’s Earthshot Prize Awards hosts, Ted Lasso actress Hannah Waddingham and This Is Us star Sterling K. Brown were also on the guest list, along with former New Zealand prime minister Jacinda Ardern.

The five winners on Tuesday night included one from Hong Kong that is working on building cleaner, recyclable lithium-ion batteries that are used in electric cars, and another that tightens marine enforcement to end illegal fishing and support ocean conservation.

Representing six continents and chosen from over 1300 nominees, the 15 finalists’ projects ranged from a scheme to plant, grow and digitally track trees in Liberia to a less carbon-intensive method of treating industrial wastewater.

This year was the first time finalists attended the awards ceremony in person, Kensington Palace said.

William, who became heir to the British throne after Queen Elizabeth died in September last year, set up the prize in 2020. Its name is a nod to former US President John F Kennedy’s ambitious “moonshot” project and goal for the 1969 moon landings.

During his four-day trip to Singapore, one of Asia’s greenest cities, William will meet Singaporeans and “learn about how local organisations are working to protect and restore our planet – from tackling the illegal wildlife trade and protecting the rainforest to incubating and scaling cutting edge innovations”, Kensington Palace said.

It is the 41-year-old prince’s first trip to Singapore since 2012, when he visited with his wife Kate. The Princess of Wales was absent from this year’s Earthshot ceremony.

“Catherine is very sorry she can’t be here,” William told attendees.

“She is helping [eldest son Prince] George through his first set of major exams.”

– with AAP