A seaweed alternative to plastic packaging and turning carbon dioxide into rock were among the environmental innovations to scoop the Prince of Wales’s Earthshot Prize.

The winners of the prestigious award, aimed at discovering solutions that repair and regenerate the planet, were announced at a glittering “green” carpet event in the US city of Boston.

Each receives £1m to scale up their pioneering projects in the drive to secure a stable climate.

There were more than a thousand entries for this year’s awards, which were shortlisted to 15 finalists from 10 countries by a judging panel that included Prince William, Sir David Attenborough, actress Cate Blanchett, footballer Dani Alves, Fijian climate activist Ernest Gibson, Alibaba founder Jack Ma and singer Shakira.

The five Earthshot prizes are based on the key environmental challenges facing the planet.

The 2022 winners were:

Clean our Air:

Mukuru Clean Stoves, Kenya – A start-up providing cleaner-burning stoves to women in Kenya to reduce unhealthy indoor pollution and provide a safer way to cook.

Founder and chief executive Charlot Magayi said: “Mukuru Clean Stoves began as a solution to a problem that I had felt personally in my own life.

“Today, we have an opportunity to transform the lives of millions, with cheaper, safer and more sustainable cookstoves and fuels.

“It is a privilege to be recognised by The Earthshot Prize as we embark on the next step in our journey.”

Protect and Restore Nature:

Kheyti, India – A pioneering Greenhouse-in-a-Box has been designed by the firm to help smallhold farmers reduce costs, increase crop yields and protect livelihoods by providing shelter from unpredictable weather and destructive pests in communities on the frontline of climate change.

Co-founder and chief executive Kaushik Kappagantulu said: “The world depends on its smallhold farmers and yet their lives are amongst the hardest on earth.

“Our Greenhouse-in-a-Box is empowering farmers in India today.

“The steps we have already taken at Kheyti are now building to change farmers’ lives at scale.”

Revive our Oceans:

Indigenous Women of the Great Barrier Reef, Australia – The innovative scheme is helping to develop a network of next generation women rangers drawing on generations of traditional knowledge and technology, such as drones, to help protect and restore the natural habitat.

Managing director Larissa Hale said: “This place has always been our home, but today we risk losing it and the unique culture that has existed here for millennia.

“Our women rangers network exists to protect our home and continue our traditions.

“We have made big first steps, but we have a long way still to go.”

Build a Waste-free World:

Notpla, UK – The London-based entrepreneurs have developed an alternative to plastic made from seaweed and plants that can be used to create a range of packaging products, such as a bubble to hold liquids, a coating for food containers, and a paper for the cosmetic and fashion industry.

Co-Founder and chief executive Pierre Paslier said: “Fourteen million tonnes of plastic enter our oceans each year.

“We founded Notpla when we discovered the solution lies in our oceans too.

“We are already replacing plastic that plagues our seas, and working with seaweed farms that give back to the environment and the local economy.

“Thank you for recognising us as we take our next big step and eliminate single-use plastic for good.”

Fix our Climate:

44.01, Oman – An innovative technique has been created by the business to turn carbon dioxide into rock and permanently store it with no need for long-term monitoring, while providing new employment to engineers and geologists working in the fossil fuel industry.

Founder Talal Hasan said: “The answers to the problems our planet faces can often be found in the natural world.

“At 44.01, we have found a natural process that removes carbon and we’ve accelerated it.

“We believe this process is replicable globally and can play a key role in helping our planet to heal.”

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Analysis – Royal visit overshadowed by barrage of bad news

The Princess of Wales showed off her eco-credentials in wearing a striking green, rented gown to the awards ceremony, where guests had been encouraged to dress sustainably.

The royal couple were joined by celebrities including Hollywood actor Rami Malek and former England football captain David Beckham, while artists performing on the night were Billie Eilish, Annie Lennox, Ellie Goulding and Beyonce proteges Chloe x Halle.

The awards ceremony was the culmination of a three-day visit by the royal couple to Boston which has been overshadowed by a race row that saw William’s godmother Lady Susan Hussey resign as a royal aide after she repeatedly questioned a prominent black British-born domestic abuse charity boss about where she “really came from”.

A trailer promoting the Duke and Duchess of Sussex’s Netflix documentary series was released on Thursday, with the timing seen by some royal commentators as a snub to William and Kate.

Earlier, William met US president Joe Biden at the end of the royal’s visit to John F Kennedy’s Presidential Library and Museum, and held a 30-minute discussion which a Kensington Palace spokesman described as “warm, friendly and substantive”.

The spokesman said Mr Biden was keen to learn about the Earthshot initiative and the finalists.

The prize was inspired by the 1960s Moonshot challenge set by then-President Kennedy with the goal of putting a person on the moon within a decade.

It is the second set of Earthshot Prizes awarded, with the first ever awards made last year.

Presenting the Clean Our Air award to Mukuru Clean Stoves, Kate told Earthshot guests: “To breathe clean air is something so many of us take for granted, but sadly for millions of people around the world, it is not a given.

“From smoke enveloping cities to the impact seen in nature, air pollution poses a threat that knows no borders.

“Heartbreakingly, over 250 million children under the age of five are breathing polluted air every single day. And this fact is even harder to hear, because we know the significant impact pollution has on our life-long development.”

Closing the event, William told the audience: “I believe that the Earthshot solutions you have seen this evening prove we can overcome our planet’s greatest challenges.

“And by supporting and scaling them, we can change our future.

“Alongside tonight’s winners and finalists, and those to be discovered over the years to come, it’s my hope the Earthshot legacy will continue to grow, helping our communities and our planet to thrive.”