Fifteen finalists were on Friday named on the shortlist for Prince William's Earthshot environmental prize to reward innovative solutions to the planet's biggest problems.
They include an Indian teenager who has designed a solar-powered ironing cart, and Costa Rica, which is pioneering a project to pay people to restore natural ecosystems.
A clean energy project in Nigeria, a food waste hub in Milan, Italy, a coral replacement scheme in the Bahamas, and a clean air app from China are also on the list.
Five overall winners will be announced at a ceremony in London on October 17 and each will receive £1 million ($1.4 million, 1.2 million euros) to support their initiatives.
William called those on the shortlist for the inaugural award "innovators, leaders and visionaries".
"They are working with the urgency required in this decisive decade for life on Earth and will inspire all of us with their optimism in our ability to rise to the greatest challenges in human history," he said.
The Earthshot Prize, launched in October last year, was inspired by US president John F. Kennedy's "Moonshot" project in the 1960s to put a man on the moon.
Each of the finalists -- chosen by experts from more than 750 nominations -- will be given help from leading private sector businesses to develop their projects.
They are competing in five areas: how to protect and restore nature; clean our air; revive our oceans; build a waste-free world; and fix our climate.
The shortlisted candidates are:
- Protect and restore nature:
Pole Pole Foundation (Democratic Republic of Congo)
- Clean air:
The Blue Map App (China)
Vinisha Umashankar (India)
- Revive oceans:
Coral Vita (Bahamas)
Pristine Seas (USA)
Living Seawalls (Australia)
- Build a waste-free world:
City of Milan food waste hubs (Italy)
Wota Box (Japan)
- Fix our climate:
AEM Electrolyser (Thailand/Germany/Italy)
Reeddi Capsules (Nigeria)