Thermal energy output dropped 25.9% on the year to 10.75 billion kilowatts hour, the statistics institute INS said.
Hydropower production rose 18.4% to 6.8 billion KWh in the first five months of 2013, while nuclear output was up 1.4% to 4.73 billion KWh.
Wind farm output more than doubled to roughly 2.16 billion KWh, from 1.05 million KWh in the January-May period last year.
Romania’s primary energy resources fell 14.2% on the year to 12.29 million tons of oil equivalent in the first five months of 2013, the data showed.
Electric energy resources were down 7.1% to 24.73 billion KWh, largely due to a 5.9% decline in production.
Romanian final power consumption reached 21.08 billion KWh in the first five months, down 7.7% from the same period of 2012. Public illumination fell 9.1% on the year, while household consumption was down 1.3%.
Electric energy exports declined 16.8% year-on-year to 479.5 million KWh in the January-May period.