Of the approximately 313 MW of new geothermal capacity that came online last year, most of it was from small binary/organic rankine cycle (ORC) projects, but the dominance of new binary/ORC installations in 2015 is not indicative of how the geothermal market will grow in the future, according to a report from the Geothermal Energy Association (GEA).
Flash technologies account for about 58 percent of global geothermal production, dry steam about 25 percent, and binary/ORC 16 percent, the report said. (See Figure 1.)
Released in March, the 2016 Annual U.S. & Global Geothermal Power Production Report estimated that binary/ORC will “continue to grow substantially in tandem with the flash and dry steam markets.”
The growth of flash, dry steam, and binary/ORC turbine technologies is directly tied to their specific applications in the market, report author Benjamin Matek, Industry Analyst & Research Projects Manager for GEA, told Renewable Energy World. Flash and dry steam technologies are suited to high-temperature resources, while binary/ORC can produce power from lower temperature resources.
Figure 1 — Operating Capacity by Technology Type Credit: Geothermal Energy Association
“The way geothermal gets developed is that higher temperature resources are developed first, then lower temperatures are developed second,” Matek said. “In the U.S., we’re developing a lot of binary now because we built out our high-temperature resources — except, for example, in the Salton Sea.”
Some other countries that are active in geothermal development, such as Indonesia, the Philippines and Kenya, for example, are still building out high-temperature fields with flash/dry steam systems, and later may start to build in lower temperature fields with binary/ORC systems, he said. He added that some countries only have low-temperature resources, and therefore are only developing with binary/ORC technology.
Additionally, the report noted that South and Central America, which are in the process of understanding their geothermal resources, likely will develop a balanced mix of binary/ORC, flash and dry steam projects are their markets grow.
Providers of high-temperature turbine technologies include Toshiba, Mitsubishi and Fuji, the report said. In addition, Ormat Technologies currently covers most of the lower temperature turbine installations, but other providers, such as Electratherm, Exergy and Turboden, have entered the market.
EGS — On The Cutting Edge
Researchers, government agencies and industry participants point to enhanced geothermal systems (EGS) as the next of wave of technology that will enable developers to tap untold amounts of geothermal resources around the world — especially those with little-to-no hydrothermal activity. But the time frames for making EGS a market reality are uncertain.
Understanding those time frames requires an understanding of the definition of EGS.
“Depending on how you define EGS, it’s either a ways off, or it’s already here,” Chad Augustine, Geothermal Energy Engineer/Analyst for the National Renewable Energy Laboratory (NREL), told Renewable Energy World.
According to Augustine, the idea behind EGS is to find ways to build geothermal energy production where underground hydrothermal activity is reduced. If a developer drills deep enough, he said, hot rock exists, but often that rock does not have the ability to circulate fluid like the natural hydrothermal systems used in traditional geothermal projects today.
“With EGS, the technology either enhances an existing fracture network or creates one and builds an underground heat exchanger so fluid can be injected into the ground, circulated through that rock, where it heats up and comes to the surface,” Augustine said. “At the surface, it’s just like any conventional geothermal power plant, where binary cycle or perhaps even a flash cycle is used to generate electricity.”
One definition of EGS technology is for what Augustine calls greenfield projects, where there is no indication of an existing hydrothermal system. An alternative definition is any adjustment made to a well or to the subsurface to enhance its permeability and make it into a commercially viable geothermal project.
It will be a while before greenfield EGS projects become a significant part of the market, Augustine said, without committing to a specific time frame for that development. On the other hand, progress already is being made in using EGS to enhance existing wells, make wells more productive, and access parts of existing reservoirs that have low permeability.
In the U.S., for example, five projects received funding under the The American Recovery and Reinvestment Act of 2009 to advance the application of EGS. Those U.S. Department of Energy-funded projects include:
- Ormat’s Desert Peak project in Nevada
- Altarock Energy’s Newberry Volcano projects in Oregon
- Calpine Corp.’s Geysers project in California
- The University of Utah’s Raft River project in Idaho
- Ormat’s Brady’s Field project in Nevada
Augustine said the projects made progress in demonstrating the benefits of EGS. Ormat, for example, successfully enhanced the operating geothermal field at the Desert Peak project by stimulating an injection well that had very low permeability.
Image: Ormat Technologies’ Geothermal Power Plant, Steamboat Spring, Nevada. Credit: Wikimedia Commons — Rjglewis
“The company injected water into the well in order to open up the fracture network and increase the well’s injectivity,” he said. “It worked to the point where they were able to increase the output of the power plant by an additional 1.7 MW.”
NREL’s involvement in EGS advancement is primarily related to analysis. Augustine said that based on findings so far, NREL has determined that, even with limits on how deep developers can drill, there is a lot of EGS potential in the U.S. The potential, he said, is so large that it is almost “more than it’s worth quoting a number for.”
He did, however, point to findings from analysis completed in 2008 by the U.S. Geological Survey that he believes produced a “fair” estimate of 500 GW of EGS potential at depths between three and six kilometers.
Most of that potential in the U.S., he added, is based in the Western states.
Other studies have looked at EGS potential down to a depth of 10 kilometers, but Augustine said six kilometers is a more realistic drilling depth — both in terms of technology and cost.
“We can drill at 10 kilometers but it gets expensive,” he said. “Six kilometers is a more realistic cut off in terms of the ability to drill that deep and the ability to drill that deep at a reasonable price.”
GEA Report Takeaways
The GEA’s power production report found that the global geothermal market currently is at 13.3 GW of operating capacity in 24 countries, and planned capacity under development is 12.5 GW in 82 countries. In addition, the geothermal market is expected to reach 18.4 GW by 2021, and 32 GW by the early 2030s.
That growth, according to GEA’s Matek, has been estimated by measuring increased support for geothermal at the government level around the world.
He said that countries are starting to increase their geothermal goals to match the pledge made by the United Nations and the International Renewable Energy Agency for a five-fold growth in installed geothermal capacity by 2030. In addition, about two dozen countries have listed geothermal in their Intended Nationally Determined Contributions as a resource they expect to tap to comply with the Paris Agreement.