By Alex Kirby
BBC News Online environment correspondent
An ambitious experiment in sustainable living has been started by green groups near the Portuguese capital, Lisbon.
The development will protect these coastal dunes
The project, the first of five, will provide homes, leisure facilities and work spaces for up to 30,000 people.
It is planned to show how communities can eliminate damaging pollution and rely on renewable energy, with zero carbon emissions and almost zero waste.
The project is the brainchild of WWF, the global environment campaign, and a UK development group, BioRegional.
Overwhelming the planet
It is intended to demonstrate how the Earth's rising population and its desire for higher living standards can be accommodated with the resources available.
The Lisbon project, Mata de Sesimbra, costing 1bn euros (£669m), will cover 5,300 hectares (13,000 acres) when it is completed in about 10 years' time.
Similar developments, each providing for about 5,000 people, are planned in the US, China, South Africa and Australia, with homes, schools, factories, health and leisure facilities, local food sources and sustainable transport networks.
There will also be a second European scheme in the UK, in the Thames Gateway east of London.
The World Wide Fund for Nature (WWF) says humanity is consuming resources and overloading ecosystems faster than the planet can renew them.
If everybody in the world enjoyed the lifestyle of an average European, it says, we should need three Earths to supply all our needs.
A nature reserve and forest restoration project will occupy 4,800 hectares (12,000 acres) of Mata de Sesimbra. Corridors will link it to protected areas nearby.
All the energy the residents use will come from renewable sources, and rainwater collection and waste water recycling should mean big cuts in water consumption and irrigation.
The developers say the amount of waste being buried in landfill sites will be reduced to no more than 25% of the national average.
Where Mata de Sesimbra will rise
They aim to provide 50% of the community's food from within 50km (31 miles), both to cut transport costs and to boost local farming and fisheries.
WWF says tourism in the Mediterranean is one of the heaviest consumers of water and a main cause of habitat destruction.
Proof of concern
So Mata de Sesimbra will also seek to develop sustainable alternatives to mass tourism, and will provide hotels and holiday homes.
The development will be built using reclaimed and recycled materials whenever possible, and at least 90% of its organic waste will be composted.
Jennie Organ of BioRegional told BBC News Online: "These projects will be making a big statement that people are interested in this kind of development.
"There'll be centres for learning in each of them, and while we're not the entire answer, these will be living, working communities. We hope the ideas can be taken further forward."
Images courtesy of BioRegional Development Group.