Illinois lawmakers have signed off on a measure involving plans to build a southern Illinois plant that would convert coal into synthetic natural gas.

The Illinois Senate, by a 31-21 vote early Wednesday, passed the measure to build the coal-gasification plant near Waltonville in Jefferson County.

The measure pushes state gas utilities to sign 10-year contracts to sell gas the plant would produce, making it easier for Power Holdings of Illinois LLC to get funding for the project.

Backers of the project say it would create 1,500 construction jobs and 700 permanent positions, although the gas produced may be more expensive for customers. Critics also worry the plant’s emissions would harm the environment.

The Senate rejected a measure to establish a similar plant in central Illinois’ Christian County.