From fossil to green

In the year 2040 we will have to feed 9–10 billion people and to provide them with energy and materials. We want them to live according to the requirements of a developed society, and we do not want to pollute the earth or change the climate. The question addressed in this contribution is whether this scenario—sustainable technological growth—is technologically possible on a world wide basis. In 1996, more than 80% of the world’s energy demands (350 EJ a–1) originated from fossil resources (mineral oil, coal and gas) and the same holds for organic raw materials. In view of the exhaustion of fossil resources and environmental considerations, our radical hypothesis has been that we will no longer use fossil organic resources from, let’s say, 2040 onwards.