“But this won’t materialize unless there are credible policy frameworks in place as well as stable access to long-term sources of finance. Neither of these conditions should be taken for granted. There is a real risk of shortfalls, with knock-on effects on regional or global energy security, as well as the risk that investments are misdirected because environmental impacts are not properly reflected in prices,” she said.

The investment would need to rise from the current $1.6 trillion a year to $2 trillion by 2035. The energy efficiency baseline would need to quadruple to reach $550 billion, according to the report by the organization working to ensure reliable, affordable and clean energy.

More than 80 percent of the total $48-trillion investment would go into energy supply and the rest in energy efficiency, the report said.

Government investment has so far grown the fastest in the renewable energy sector, comprising now 15 percent of all annual funds spent on energy together with biofuels and nuclear power. Oil and other fossils industries still take the majority of money - more than 1 trillion a year.

The amount spent on the renewables will increase to nearly $10 trillion for renewables in the course of the next 20 years, the report says.

“Policy makers face increasingly complex choices as they try to achieve progress towards energy security, competitiveness and environmental goals,” IEA Chief Economist Fatih Birol said in the statement.

“These goals won’t be achieved without mobilizing private investors and capital, but if governments change the rules of the game in unpredictable ways, it becomes very difficult for investors to play,” he said.