The idea could apparently “save the world” and cost around £2.7billion.
However, Mr Poland did not back it.
He said in 2018: “There are no plans to actually do this, it was just a plan in concept.
“But there is no plan to do any drilling at Yellowstone and I can’t imagine it would ever be allowed as it is a national park.
“It would not have the intended effect either – it’s not even a good idea.”