... try 10 tonnes an hour. 8 tonnes if the plane is empty. 12+ at TOC following MTOW!
As for sustainable, I don’t think the earth will be running out of oil anytime soon. If it’s carbon emissions that are of concern, look back through the annals of history and see how carbon ppm now compares to times long ago. Also, note that airliner traffic contributes very little to the total amount of global carbon emissions.