An 18-month trial of a controversial fuel at Drax power station near Selby has had no adverse impact on local health, the Environment Agency said.
The fuel was burned in one of Drax's six boiler units
The station, which produces 10% of the electricity in England and Wales, had £1m of modifications for the trial.
The plant burned a mixture of coal and up to 15% petroleum coke (petcoke), an oil-based fuel which is a by-product of the petroleum industry.
Drax said they would now apply to burn the fuel in all their six boiler units.
The Environment Agency said they were satisfied with the data, which covered burning the fuel mixture in one boiler.
Drax said there had also been no noticeable effect on the quality of water discharged after use in the cooling process and treatment of by-products.
Dr Nigel Burdett, head of environment at Drax, said: "No operational problems have arisen when burning a blend of coal and petroleum coke, and monitoring of our handling, transport and fuel transfer arrangements confirm this.
"Overall the findings show that burning a coal and petroleum coke blend is similar to that for a coal-only operation and, therefore, there has been no change in environmental impact on the local environment as a result of the trial.
"The trial data reinforce the predictions we made before the trial in 2002 and we are able to conclude that, in this test, burning a coal and petroleum coke blend has presented no threat to public health."