Geothermal technology, though over a century old, is constantly changing. Developments in mapping techniques have improved exploratory practices. Plant adaptations, such as hybrid technologies and the introduction of fully flexible mode, have enhanced operations. And cutting-edge research continues around the globe, with goals of improving plant efficiency and performance. With geothermal technology—arguably more so than with other generating technologies—plant design determines one’s operating options, so we begin with some of the latest plant design innovations.
Geothermal Reservoir Discovery
To establish a plant, first a company must find a suitable heat source. A core area of geothermal interest is risk reduction, because drilling is chancy. One effort to develop a reliable science-based exploration and assessment method for identifying geothermal reservoirs is the Integrated Methods for Advanced Geothermal Exploration (IMAGE) project. Funded by the European Union, the project is redefining geothermal exploration, making the drilling process more precise. With an advanced methodology, IMAGE partners are increasing the likelihood that a geothermal reservoir is discovered during the exploratory phase.
Geothermal surveys currently combine several approaches to find areas with high geothermal potential, similar to oil and gas exploration. IMAGE researchers in several European regions are using a mixture of novel survey techniques to accomplish their goals, including geophysical techniques such as ambient seismic noise correlation and magnetotellurics with improved noise filtering; fiber-optic down-hole logging tools to assess subsurface structure, temperature, and physical rock properties; and the development of new tracers and geothermometers.
Overall, IMAGE is refining the prediction process through studying reservoir factors like fracture permeability, temperature, and in situ stresses. Once field and laboratory data is fully analyzed and incorporated, it will be used to enhance current geothermal exploration techniques. IMAGE is just one of many studies under way that are revolutionizing the exploratory process involved in geothermal plant creation.
Maximizing the Value of Thermal Energy
Mike Long, senior project manager for the Strategic Consulting department at POWER Engineers—a consulting services and engineering firm headquartered in Idaho—confirmed that technological innovations in geothermal plant exploration and operations are changing the industry. His firm has noticed multiple institutional efforts being made to improve the success rate in identifying new areas of significant geothermal potential and exploratory activities to mitigate resource development uncertainty and cost. According to Long, “The success of these efforts on the resource side drives new power plant projects.”
Long’s firm has seen a focus on better overall use of geofluid energy, resulting in more efficient plants. “In the past, a more conservative approach was taken to install single-pressure steam-condensing plants. We are now starting to see combinations of double- and triple-pressure steam-condensing plants with bottoming cycle binary plants,” Long said