The geophysicists and seismologists and geodynamicists who get paid to figure this stuff out have come to the conclusion that earth's core is a giant molten nucleus generating temperatures in the range of 5-6000 degrees C.
That would keep a lot of steam turbines making electricity in perpetuity!
All we'd have to do is drill a hole about 3,000 miles deep. I know that's a big number, but it's doable.
Conventional drill rigs can do 300-800 feet per day. Just for a bit of math fun let's assume we're heading to the earth's core at the rate of 500 feet per day. That would take us a mile every couple of weeks. Two miles and a bit every month. A good twenty-five miles a year!
The scientists aren't sure exactly where the 5000 degree core begins, but it's safe to say that somewhere between 150 and 200 years from now we'd be there!
And it wouldn't be free of course.
It'll cost a pretty penny and then some to drill a 3,000 mile hole. Pretty sure only Exxon and her ugly sisters have the pockets for such a venture...
Then they'll need to recoup their expenses and make a return on their hard capital and their soft capital, and their exploration capital and their imaginary capital and blah blah blah....
By the time it's all over it'll be cheaper to just buy their oil.