Geothermal energy doesn't get as much press as other forms of renewable energy--although I guess you could even quibble about the distinction between "renewable" and something that depletes over geologic timescales. When most of us think of geothermal, what we are really talking about is a somewhat rare subset in which nature has kindly brought together both the heat source, hot rock deep in the earth, and a working fluid, water. The problem with this kind of reservoir is that they often occur far from any potential electricity or heating needs. MIT's Technology Review reports on a major advance towards tapping the much larger, more widely dispersed resources of dry rock geothermal energy.
This is exciting, because geothermal energy has many potential benefits, few drawbacks, and is available on a scale that could ultimately meet most of our future energy needs, if it could be tapped efficiently. Unlike wind and solar power, it flows continuously, reducing the development threshold by making expensive power storage capacity unnecessary.
We shouldn't minimize the challenges of scaling up an experimental setup like this, and replicating it in many different locations. Researchers have been pursuing this goal for decades, and there will doubtless be engineering problems to be solved along the way. Still, given the tremendous potential payoff if it proves successful, one wonders why funding for this kind of technology hasn't been a higher priority. Although the European project cited above still appears to have some technical hurdles to overcome, including minimizing its noise impact, it seems like a very promising advance.