In a speech on "Shell scenarios for the 21st century," Royal Dutch Shell CEO Jeroen van der Veer said that most renewable energy sources were still far too expensive, even compared with higher prices for oil, gas and coal.

He also said that the reserves of oil and gas that were easily accessible and close to the markets where they were required were depleting. Extracting new supplies would require much larger investments per unit than in the past.

Van der Veer said Shell saw two broad scenarios: a scramble in which countries "fight for themselves" on energy policy and set their own rules with minimal cooperation, or a "blueprint scenario", where governments cooperated to create large markets with common standards. In the first, much time would be lost on making inroads into cutting carbon emissions. The second would be much more favorable to pricing C02 in a consistent way.