The NSW government stands to lose more than $10 billion in mining royalties between 2023 and 2035 if the proposed Adani mine and other coal projects in Queensland's Galilee Basin go ahead, new research shows.

Economic modelling by the well-known resource analytics firm Wood Mackenzie found new coal supply from new mines in the Galilee Basin would reduce the price of coal by 25 per cent and cut NSW coal exports by about 80 million tonnes a year.

A separate report by the Australia Institute think tank has used that modelling to estimate the impact on the NSW budget from lost mining royalties.

"Based on Wood Mackenzie's analysis, the development of the Galilee Basin will reduce the value of NSW coal royalties by $10.2 billion to 2035," it concludes.