NV Energy turns on two new geothermal plants

Two plants totaling 65MW of generation capacity located in northern Nevada were announced yesterday by NV Energy and were built by Italian headquartered company Enel North America.

The two plants cost 200 million dollars and will provide 400 million kWh of energy annually, which is enough for 60,000 homes. The 400 million kWh from 65MW is a capacity factor of 70%, which is low from my understanding of geothermal, though its possible its just a conservative estimate.

Capacity factor is one of the most important things to consider when comparing renewable energy sources – solar has an average capacity factor of 25%, and wind is about 30%. This means that over the course of a year, the facility is only outputting power at 30% of its rated capacity, so a 100MW wind farm is on average outputting 30MW at any given time. Geothermal generally has very high capacity factors, between 75-90%, which means that an equivalent solar power system would need to be about 200MW to produce the same 400 million kWh of energy annually.

The problem of course is that geothermal resources are very limited. Nationally, geothermal is really only feasible in the western US, in states like Nevada, Idaho, Wyoming, Utah and Oregon. The total estimated recoverable geothermal-based energy is about 20-25GW in the western US, with “enhanced” geothermal systems (still primarily in the research and development phase, with a few operational plants in production) providing an additional recoverable 80GW of energy. This baseload of roughly 100GW could provide the current (2009) baseload needs for the western United States, eliminating the need for coal, nuclear and natural gas baseload power plants. Natural gas would still be needed for peak loads, but combined with solar PV and thermal we can manage to generate and store that energy for peak load in the winter and summer. This also doesn’t account for the increase in per capita energy consumption, which is where effciency programs like Energy Star come in to play.

Geothermal resources in northern Nevada underscore need for a proposed north/south 500kV line to connect northern geothermal to Las Vegas. and points beyond. It is estimated that there is a total of 2.5-3GW worth of conventional geothermal available in the state, which would account for a significant piece of the baseload energy the state needs. At our current rate, we are building about 100MW per year, with a current installed capacity of roughly 370MW of geothermal resources in-state, we will reach this in about 20 years.