An emissions intensity scheme could become official policy of the NSW Nationals on Friday, a move that would represent a split from the federal leadership and a challenge to the Turnbull government's climate change agenda.

After the state's Young Nationals backed the contentious proposal in April, the motion will be on the agenda at the party's annual conference, a two-day gathering that will draw hundreds of rank-and-file supporters, as well as Deputy Prime Minister Barnaby Joyce.

The call for a national emissions intensity scheme will be hotly contested as will the removal of abortion from the NSW Crimes Act and an increased Syrian refugee intake.

The policy battles highlight the generational evolution taking place within the party, which is deeply conservative at a parliamentary level but more socially and environmentally progressive among younger members.