The International Energy Agency (IEA) published the Energy Technology Perspectives (ETP) 2014 last June. The document is the IEA's biennial flagship publication concerning energy technology solutions for a sustainable future.

The ETP 2014 states that a revolutionary reversal of shares of power sources needs to occur to achieve almost zero carbon generation in order to contain the atmospheric temperature rise in the end of the century to two degrees Celsius (2DS scenario). Today, 68% of electricity is generated from fossil fuels, with 20% coming from renewables, while in 2050, the 2DS indicates that 65% needs to come from renewables and 20% from fossil fuels.

There are three apparent challenges.