Why don’t we use the the heat near/at the earths core to run power stations etc.?Is it that more expensive/dangerous than nuclear plants or whatever?I would think that would be an endless supply of heat,at least 'till the earth ends hehe when of course we would not need it any more.
Geothermal power is used in some places, but you need a location where a significant amount of that heat comes close enough to the surface for us to access it. We don’t even have the technology yet to dig all the way to the crust, much less clear to the core. I think that there are plants of this sort in Iceland and New Zealand, and it would probably work in Yellowstone, but there aren’t many other places where it would.
There are some geothermal wells. You can learn some more at the DOE’s Geothermal Energy Program site.
As far as “near/at the earths core” goes, we are not technologically able, presently, to get anywhere close to the earth’s core. But, we don’t need to in order to exploit geothermal energy.
Your question is about equivalent to saying, we’ve been to the moon, why don’t we fly off to the stars? Our technology is not a fraction sufficient just to get to the earth’s core, much less do anything useful when we get there. Which would require solving the problems of how to have things function under conditions of incredible heat and pressure (and possibly radioactivity).
We don’t do it because today and for the foreseeable future, it’s utterly impossible.
I meant was as close enough to get water to boil for turbines.now if that means a distance that is unattainable today ok I got your answer .
How far would you have to dig to get to that temperature anyway?
Ok I read the articles on the url posted by ringo,I think that clears up my question a lot
The geothermal gradient varies from place to place, but it averages 15º F/1000 ft of depth.
The Naval Petroleum Reserve #1 well in Elk Hills recorded 431º F at its total depth of 24,426 feet.
I read about this many moons ago and IIRC corrosion is one of the factors that prevents it. That is among many others.
Sure we do. It’s called a “shovel”. 
(Yeah, you meant “through the crust”… I’m just a wiseass.)
There are such things as working geothermal power plants; here’s one just down the road from me:
FYI:
You need not get anywhere near the earth’s core. Indeed, getting to the earth’s core would likely be impossible as you would be ‘digging’ through molten magma.
As pointed out you just need to get a good ways down in the earth’s crust or find a particularly thin spot of the earth’s crust where the heat is close to the surface. Getting heat out of mines so miners can work has long been a problem. At any significant depth the mining company builds huge air conditioners (in effect) to blow cold air into the mine. Of course, miners don’t usually get anywhere near places where you could boil water but it lends credence to the notion of things starting to get hot underground.