For some time now, I've been quietly rooting for geothermal power. It's clean, it's cheap, and unlike solar or wind, it provides a base load of power that doesn't depend on the sun shining or the wind blowing.

Sure, I spend much more time writing about the twists and turns of the solar industry, but that's because there are so many more publicly traded solar businesses. Mining company legend Ross Beaty recently brought Magma Energy public, but it's listed in Canada. Beyond Ormat (NYSE:ORA), the pickings this side of the border are quite slim.

In recent months, I've been extremely heartened by one geothermal report, and deeply disappointed by others. Let's start with the positive.

Rocking the alternative-energy world
A study, published in the journal Energy Policy, has found that geothermal is both the most efficient alternative-energy technology and is also improving at the fastest rate. Wind power places second, while solar does not fare nearly as well, despite receiving the most government funding among emerging technologies.

The authors, from NYU's Stern School of Business, used a technology S-curve model that should be familiar to anyone who's read the work of Motley Fool CAPS mentor Clayton Christensen. Picture flattish growth, followed by exponential growth, and then a flattening again -- hence the "S" shape. Geothermal and wind technologies are both in that steep middle phase, where they are making rapid efficiency gains, translating to a high return on R&D investment. Wind is further along that curve, while geothermal has shown no signs of slowing performance improvement. Solar is improving much more slowly.

With geothermal poised to surpass the efficiency of fossil fuels with just a few billion dollars' more support (the authors peg the cost at $3.3 billion), the policy implications of this study are that our government funding priorities are out of whack. Imagine that.

Wait one hot minute
This is exciting stuff, but for geothermal to take the world by storm, it has to move beyond the exploitation of natural reservoirs such as occur at Calpine's (NYSE:CPN) Geysers facility and move to Enhanced Geothermal Systems (EGS) that can pull the heat out of hot dry rock. Unfortunately, such projects have seriously stumbled lately.

First there was Australia's Geodynamics, which had an explosion at its Habanero 3 well in April. Commissioning continues to be delayed at the company's pilot plant.

More recently, AltaRock Energy suspended drilling at the Geysers after failing to make it more than a third of its way to total depth. You may recall this as the company in which Google's (NASDAQ:GOOG) philanthropic arm took a monetary interest somewhat over a year ago. There are some heavy hitters on board from the venture capital community here, and even the government has dished out a little cash to this deep driller.

Anybody here know how to run one of these drills?
This is disappointing stuff, but drilling difficulties are hardly an insurmountable challenge. Look at Transocean (NYSE:RIG), which just drilled a record 35,055-foot well in more than 4,000 feet of water, uncorking a giant gusher for client BP (NYSE:BP) in the Gulf of Mexico. The geothermal industry, with a fraction of the government money thrown at fossil fuels over the years, will figure out how to drill through 12,000 feet of rock.

That road to commercialization of EGS would certainly be easier if the oil and gas industry would clue the geothermal folks in on the dark arts of deep drilling. The conspiratorially minded among us may conclude that the energy majors have no such interest in doing so, since they have a good thing going with fossil fuels. Even though Chevron (NYSE:CVX) is the biggest geothermal producer in the world, I certainly don't see the company doing a lot to push the EGS envelope.

I probably wouldn't expect too much from this group, given the clear preference by companies such as Royal Dutch Shell and ExxonMobil (NYSE:XOM) to stick to biofuels. But with or without a helping hand from the hydrocarbon camp, I do expect the geothermal business to grow by leaps and bounds in the years ahead. Whether you should risk your own capital in one of these enterprises is a question for another day.