A 750 megawatt coal-fired power plant in north Queensland would be viable, but only if wholesale electricity prices remained as high they are today and a carbon price is never introduced over the next 40 years.

The leaked private consultants' report published in News Corp newspapers on Wednesday also warned there was a “serious risk” the $1.6 billion plant may become a “stranded asset” because the demand for coal is dropping.

Anti-coal protesters dogged Premier Annastacia Palaszczuk in Cairns on Wednesday. Credit:Darren England/AAP

Queensland’s wholesale electricity price is monitored by the Australian Energy Market Operator and the wholesale price of electricity varies constantly, minute by minute.