Sweden has come top of the new Energy Transformation Index (ETI) developed by the Fraunhofer Institute ISE and the International Solar Energy Society (ISES).

The index, which will be published regularly from now on, measures a country's progress in reaching 100% renewable energy while also boosting the energy efficiency of its economy.

Sweden came top with a score of 40 while Brazil finished just behind on 39 and Italy on 34. Japan, Britain and Germany all scored 30.

"So far there has been no methodical approach with which we could describe the progress of individual countries and regions quantitatively on the way to the energy revolution," said Prof. Dr. Eicke Weber, director of Fraunhofer ISE.

The index views 100% renewable energy and an economic output of US$2 of GDP per kWh, double Germany’s level today, as the end destination for countries.

By measuring how close countries are to this point and how well they are doing at improving both measures in tandem, a quantifiable value can be achieved.

The index also looked at how well countries had done since 1990 with Germany and the UK winning out.

Weber said he hoped the index could be published annually and extended from the current 17 countries to 82.

"We expect that this regular publication provides a further incentive to really deal effectively with the global task of the energy revolution," said Weber, adding that it could provide a useful measure progress towards tackling climate change.