By 2025, the number of megacities (cities with populations over 10 million) will grow from 23 to 36, the United Nations forecasts, and the population in the top 600 cities in the world will grow by 500 million. In the near future, Hans-Jörg Bullinger told the World Manufacturing Forum Tuesday in Stuttgart, Germany, two-thirds of the world's population will live in megacities.

Countries such as Germany won't have such massive urban areas, but Bullinger, president of research institute Fraunhofer-Gesellschaft, warned it would be a “big mistake” for manufacturers in export-dependent Germany to ignore this demographic change.

"Our cars which we develop here will be mostly driven in megacities. We have to choose products and services which fit into the specific demands of those megacities,” he told the gathering of some 400 political and business leaders examining policy issues facing manufacturing nations and companies.

Germany is sponsoring research to develop a High-Tech Strategy for dealing with six global challenges arising from such massive demographic and technological changes: health and nutrition, safety and security, mobility and transportation, information and communication, energy and living, and production and environment.

To meet these challenges, researchers are envisioning what a “city of the future” will look like and the technologies needed to deal with a more resource-constrained future. With energy, for example, Bullinger said Germany now produces 20% of its electrical energy from renewable resources. Wind farms are being planned for the relatively shallow North Sea to boost electrical production, he noted, but transmission lines will be needed to bring that power to cities such as Stuttgart and systems built to store it. "We will want to rebuild nearly the entire power system," he said.

In a smart future city, he said, part of the energy answer will be to create a more decentralized power system. Homes will become individual power sources, with solar panels on the roof and a heat pump in the basement.