Traditional non-renewable fossil fuels are still relatively cheap to produce but environmentally expensive. Renewable energy is, by contrast, still expensive to generate but environmentally sound. So how will the world economy be powered by the end of the 21st century?

Report urges fuel revolution

The International Energy Agency has called for a global energy revolution to ensure future supplies and curb emissions.

    Dreaming of a climate bailout

    What could the $700 billion bailout of Wall Street have bought in terms of climate change mitigation?

      Small wind, big rewards? 

      Micro wind turbines are popping up everywhere. But is it worth you investing? Find out in our quick guide.

        Staring down the barrel

        Oil is expensive, environmentally damaging and, in the view of some experts, increasingly scarce.

          Calculating the cost

          Which sectors of the world economy are the biggest polluters?

            Nuclear: A necessary evil?

            Why is the debate about nuclear power so radioactive?

              Doha: Debate highlights

              Doha, Qatar: The city hosted the first of the Principal Voices round table debates on the 21st May.

              Quick Vote
              Have higher fuel costs affected your travel plans?
              Principal Voices on CNNI
              Principal Voices on CNNI

              CNN International anchor Charles Hodson presented the first Principal Voices program, "Principal Voices: Economics of Energy," which aired in late June. Watch it here.

              Part 1: Cheap abundant energy Video
              Part 2: Iceland's renewable energy Video
              Part 3: Cows to Kilowatts Video

              Jeremy Rifkin

              The internationally renowned economist, social critic and author lends his expertise on the environment and energy to world leaders.

              Olafur Grimsson

              The President of Iceland is a passionate advocate of renewable energy. Read what he had to say at the first Principal Voices debate in Doha.

              Joseph Akinkugbe Adelegan

              Joseph Adelegan is best known for the "Cows to Kilowatts" project, which creates energy from waste. Click here for his views.