As the world's population keeps on growing, and concerns about dwindling resources and climate change increase, solutions for a more sustainable city are emerging.
By 2050, the world will have more than 10.2 billion people living on it, with over 70 percent of them living in cities, according to data from the UN and the sustainable development research organization Worldwatch Institute.
But as the size of cities increase, so do the number of challenges: from how to house and feed the new inhabitants to making sure the environmental impact remains minimal.
Here are some of the latest innovations to create the future's sustainable cities.
By CNBC's Alice Tidey.