"After completion of the transaction we want to invest, and financially we can do so. We have 1.5 billion euros a year available for green energy then," Rheinische Post on Saturday quoted Rolf Martin Schmitz as saying.
RWE and E.ON in March unveiled comprehensive plans to break up Innogy and divide its assets, turning RWE into Europe's second-largest wind utility and E.ON into Europe's largest operator of gas and power networks.
The Innogy deal, which will take place in several steps due to its complex structure, is progressing well, Schmitz said.
"We are in touch with the antitrust regulators of various countries and are fully on track. I expect that E.ON and RWE will receive all approvals in 2019 and the deal can be completed," he told the paper.
At the same time, RWE is looking at opportunities to build or buy power plants, he said, but added that RWE was not interested in any of local utility Steag's plants.
Commenting on German government efforts to decide on the timetable for a withdrawal from coal as an energy source, Schmitz warned against trying to exit by 2030.
"That cannot be done, even if renewable energy could cover 65 percent of power needs by then," he said, saying that the investments necessary for such an early exit would be immense, and thousands of jobs could be at risk.
"Our staff planning is geared toward maintaining open pit mining until the middle of the century," he said.
If the government does push for an earlier exit from coal, RWE is prepared to claim damages, he said.
(Reporting by Maria Sheahan; Editing by James Dalgleish)