Oh look, someone invented Cold Fusion (again)

The poles. Also, there are huge amounts of petroleum on mud soils (the US included). Just happens that the extraction process is not as cost effective as obtaining oil from other sources (like... buying it?).

See Canada.

 Spoiler

Beautiful money!

They have an oil source that rivals those of Saudi Arabia in terms of quantity. It just happens that this source is all mixed up with mud. Thus why there's now a renewed interest on studying muds/clays. And I suppose oil companies are now researching better/more cost efficient ways to extract the oil from those fields as well.

PS: Poor muds used to be ignored because oil companies were not interested in them and geologists are lazy pineapples. But now, everyone loves mud! Happy end.

we have known about everything on the surface for at least 50 years...

i rather hope oil companies arent seriously researching oil muds/clays and oil shales. by the time they figure out how to make it cost effective / break even, those resources could have made solar profitable.