Technically yes but not practically because the temperature differential is what is needed and well as considerable logistical and engineering issues of making

Technically yes but not practically because the temperature differential is what is needed and well as considerable logistical and engineering issues of making something which uses it large enough to deal with a moving and raging fire - let alone not interfering with fightint efforts or being accused of arson to not pay for fuel. Nobody has used Centralia, PA as a generator despite the long burning underground coal fire - it has also been moving underground in a regular pattern.