The Trade Ministry said it had drawn up a plan requiring Japanese power producers to generate 16 billion kilowatt-hours of energy from renewable sources by March 2015. This would be an increase of 31 percent from the target of 12.2 billion kilowatt-hours, equal to 1.
35 percent of total output, set for March 2010.
Japan, a signatory of the Kyoto Protocol on cutting the production of greenhouse gases, wants to expand generation from clean energy sources, particularly solar panels, to help the nation meet emissions targets.
"The proposed target is very tough, and it isn't acceptable," said Mamoru Muramatsu, general manager for planning at the Federation of Electric Power Companies of Japan. "We don't even know whether we can meet the requirement" for 2010.
To reach the 2010 target, utilities need to invest about 100 billion, or $820 million, he said.