Geothermal

In 2010 investment in wind power continued to accelerate, particularly in California and Texas. California also entered several solar projects in the race for financing. The finish line that renewable power developers and their partners are racing to meet is a December 31 deadline to qualify for federal cash grants.

Most countries are trying to increase the percentage of their electricity supply that comes from renewable sources. But because capital costs for renewable generation still, in most cases, are higher per kilowatt-hour than for fossil-fueled power, governments are looking at all options for encouraging the development of greater renewable capacity. Feed-in tariffs (FITs) are one policy tool that has been used, most notably in Europe. Now North America is testing FITs as well.

One of the world’s largest geothermal power stations was officially opened this May on New Zealand’s North Island. A joint venture between Mighty River Power and Tauhara North No. 2 Trust, the new 140-MW Nga Awa Purua Geothermal Power Station increases geothermal’s share of power in New Zealand to around 14%—a proportion that has more than doubled since 2005.

As U.S. utilities increase the percentage of renewable energy in their generation portfolio, they must deal with a number of key issues related to selecting specific technologies. Additionally, they must figure out what it will take to make renewables emerge as a mainstream generating option in the future.

Mexico has already developed substantial large hydro and geothermal resources. However, without policy changes and government-sponsored financial incentives, unconventional renewable sources are taking the equivalent of baby steps.

In mid-February, the Geological Society of London raised the hopes of those promoting geothermal energy when results of exploratory drilling in Weardale, County Durham, revealed record levels of permeability in granite. Although the results are promising for the development of geothermal energy, they may have less welcome implications for the safe disposal of radioactive waste in deep repositories.

"It’s déjà vu all over again," said Yogi Berra. The Hall of Fame catcher could easily have been predicting the coming resurgence of natural gas – fired generation. Yes, a few more coal plants will be completed this year, but don’t expect any new plant announcements. A couple of nuclear plants may actually break ground, but don’t hold your breath. Many more wind turbines will dot the landscape as renewable portfolio standards dictate resource planning, but their peak generation contribution will be small. The dash for gas in the U.S. has begun, again.

(Web supplement to "Assessing the Earthquake Risk of Enhanced Geothermal Systems.") The future of geothermal energy will be driven by six primary technologies, but each will pose its own challenges.

Renewable Generation in North America

Enhanced geothermal systems (EGS) deliberately induce seismicity — earthquakes — in order to access hot, subsurface rocks for use in geothermal power generation. Recent quakes around the world have frightened those living near EGS sites and sparked controversy over the technique. We asked experts to provide EGS technical details and to evaluate the seismic risk the process poses.