Plans have been unveiled for a 2,000-home eco village on Teesside.
Wynyard Park Ltd said the project would involve fuel efficient buildings, renewable energy systems and sustainable transport solutions.
The 700-acre scheme would sit alongside the company's expanding £450m business park near Stockton, which it said would create up to 10,000 jobs over 15 years.
The company said it believed the completed project would be one of the UK's most eco-friendly developments.
Chief executive Chris Musgrave said: "We intend to build something that is right for the area.
"If we can make it work, it will bring huge benefits to the Tees Valley region both economically and socially and that will be positive for the whole community."
Wynyard Park's sustainable development director Ranald Boydell, added: "This is a fantastic opportunity to create a sustainable development starting from a clean slate.
"The technology exists to create carbon neutral communities - you just need the will to make them happen."