The Prince of Wales has described those in the running for his environmental Earthshot prize as “heroes of our time”.

Prince William will travel to Rio de Janeiro next month for the ceremony – the first time the awards have been hosted in Latin America. The prize, created by the prince five years ago, awards £1m every year to five projects for their environmental innovations.

There have been almost 2,500 nominees this year from 72 countries – this year’s winners will be chosen by Prince William and his Earthshot Prize Council which includes the actor, Cate Blanchett and Jordan’s Queen Rania.

This year’s list of finalists range from a Caribbean country to small start-up businesses.

The Earthshot Prize is a 10-year project with past ceremonies held in London, Boston, Singapore and Cape Town.

Kensington Palace confirmed earlier this year that the main awards ceremony will be held at Rio de Janeiro’s Museum of Tomorrow on 5 November.

Barbados has been nominated for its global leadership on climate with the island on track to become fossil-free by 2030.

The Chinese city of Guangzhou is shortlisted in the “Clean our Air” category for electrification of its public transport system.

Prince William previously said he would like to take the Earthshot Prize to China.

Finally, what has been billed as the world’s first fully “upcycled skyscraper” makes the final list too.

Sydney’s Quay Quarter Tower was one of thousands of 20th century towers now reaching the end of their lifespans.

Instead of demolition, which releases vast amounts of carbon and waste, a coalition of architects, engineers, building contractors and developers has effectively “upcycled” the original structure.

“Matter” is the only British finalist in the line-up.

Based in Bristol, the business has developed a filter for washing machines removing the greatest cause of microplastics in our oceans.

“I feel like winning an Earthshot prize for me would be like winning an Olympic gold medal,” said Adam Root, the founder of Matter.

In a video message released to mark the announcement of this year’s finalists, he reflected on the past five years.

“Back then, a decade felt a long time. George was seven, Charlotte, five, and Louis two; the thought of them in 2030 felt a lifetime away,” said Prince William.

“But today, as we stand halfway through this critical decade, 2030 feels very real.

“2030 is a threshold by which future generations will judge us; it is the point at which our actions, or lack of them, will have shaped forever the trajectory of our planet.”

He added: “The people behind these projects are heroes of our time, so let us back them. Because, if we do, we can make the world cleaner, safer and full of opportunity – not only for future generations, but for the lives we want to lead now.”

The Earthshot Prize is now one of the key pieces of Prince William’s public work.

“He has been able to build an unprecedented network of organisations,” Jason Knauf, the new CEO of the Earthshot Prize, said.

“The philanthropists working together, the corporates that come together as part of the Earthshot prize community, the leaders who get involved.

“There’s never been a group of people working together on a single environment project in the way they have with the Earthshot Prize. Prince William has been completely relentless in building that network.”

This year, the Earthshot Prize events in Rio are in the run-up to the COP Climate Conference which is being held in Belem on the edge of the Amazon Rainforest.