It definitely is, and it’s a relatively new one. People think about geothermal energy — when they think about it at all — in terms of the hot water bubbling up in some places, but two kilometers or so down in most places there are these incredibly hot rocks, ’cause the interior of the earth is extremely hot, several million degrees, and the crust of the earth is hot …
Wrong Al. If that were true there wouldn't be any life at all to speak of on Earth. We could probably provide heat to the moon let alone our own homes.
Here's what someone with a slightly higher IQ then Gore has to say on the matter. Via John Derbyshire:
The geothermal gradient is usually quoted as 25–50 degrees Celsius per mile of depth in normal terrain (not, e.g., in the crater of Kilauea). Two kilometers down, therefore, (that's a mile and a quarter if you're not as science-y as Al) you'll have an average gain of 30–60 degrees — exploitable for things like home heating, though not hot enough to make a nice pot of tea. The temperature at the earth's core, 4,000 miles down, is usually quoted as 5,000 degrees Celsius, though these guys claim it's much less, while some contrarian geophysicists have posted claims up to 9,000 degrees. The temperature at the surface of the Sun is around 6,000 degrees Celsius, while at the center, where nuclear fusion is going on bigtime, things get up over 10 million degrees.
I wish I could find it but Gore is making a cameo appearance on one of the NBC shows this week (I think it's 30 Rock) where he plays a custodian. One of his lines is, and I'm paraphrasing, "There's an old African proverb that I just made up ... recycle everything". Al Gore has been making up a whole lot of things.