I think one of the biggest tragedies of the entire renewable energy movement is the shameful near lack of attention geothermal energy has received. It's an extremely clean, domestic, terrorist-resistant source of energy with an incredible amount of potential for America, particularly across the western states. Perhaps it doesn't get as much attention because of the "jobs per megawatt" factor; development, construction, operation & retirement of a nuclear power plant creates many more jobs (across more state lines)per megawatt than geothermal projects ever would.

6.9 GW with 100% utilization is about 60 TWh per year. To put that in perspective, 2008 yielded about 52 TWh of wind power.

Furthermore, the elegance of geothermal is that it can be used as baseload. These plants in CA, NV, and OR+WA can be used to turn off some coal fired power plants nearby. Good stuff.

Kelly, you are absolutely right, geothermal seems like a energy bonanza, but attempts to tap it has proven deceptive, the challenges are in fact tremendous, and even the most enthusiastic supporters of this energy have cool down their hopes. Corrosion due to sulfur is alomost a showstopper. It will be used but we will have to way that energy becomes more expensive.

Anne:

Baseload doesn't have to be hard to throttle. Baseload is simply the maximum amount of electricity needed to satisfy demand 24x7x365.

The elegance is twofold:

1. Because it can be run 24x7, you get the most output per capital input -- making the cost of delivering geothermal electricity cheaper (and, implicitly, the cost of delivering coal/gas/oil electricity more expensive).

2. If it can be slightly overbuilt (if depleating the heat resource is a legit concern), then you can combine it with intermittent sources like wind to create a larger renewable, reliable baseload. For example, if you know you'll get a minimum 1,000 MWh/week from wind with Pr[.99] and your geothermal is capable of 5,000 MWh/week but can actually have an instantaneous output rate of 6,000 MW, then you can actually claim baseload of 6,000 MWh/week with Pr[.99] because you crank up the geothermal when the wind isn't blowing, but dial it back when the wind is blowing, allowing you to treat the intermittent wind power with a certainty. Any output above the 1,000 MWh/week from wind is "bonus", but right now 100% of that wind output is "bonus" and not relied upon -- and therefore not worth as much.

Wind's intermittent nature devalues it's output; combining it with a renewable reliable source that can be tempered allows accounting some wind as reliable -- thereby increasing it's value.

Currently wind tends to be effectively partnered with natural gas; when the wind blows we burn less gas. That's good, but it would be far better to burn less coal. By partnering wind with geothermal, we could burn less coal instead of less gas, and that's a better outcome... and an elegant one.

@ Anne, SJC, Stormv,

The ideal would be to have clean baseload and clean peak power sources. Given the intermittent qualities of wind and photovoltaic, we also need "instantly-available" capacity, which thus far coal, nuclear, and geothermal seem ill-suited to provide. Natural gas plants (common in California) are pretty good at quickly adapting to spikes in demand (or drops in wind and sun). Hydro, on the other hand, is awesome at handling demand spikes. By opening a (very large) valve, hydro can add gigawatts in seconds.

Just looking at the West Coast, it seems like the ideal formula is some geothermal for baseload, wind and solar when they are available (particularly during peak demand afternoons), and using natural gas and hydro to smooth the curve. Ideally, hydro would be used scarcely enough to let the largest resevoirs refill. Washington State would get solar from California, and give back Hydro as needed.