A Stanford research analyzes the techno-economics of enhanced geothermal programs throughout the continental United States underneath baseline and superior situations.
The potential for Enhanced Geothermal Techniques (EGS) within the continental United States can attain as much as 82,945 GW primarily based on business-as-usual situations and as much as 184,112 GW contemplating the state of affairs of versatile geothermal dispatch. That is based on a research achieved by Mohammad Aljubran and Professor Roland Horne from Stanford College.
The total article “Energy provide characterization of baseload and versatile enhanced geothermal programs” may be accessed through this hyperlink. The research additionally has a companion ArcGIS web-based map.
A brand new strategy to EGS modeling
A number of research have been achieved previously on the potential of EGS for energy era. The brand new research proposes to enhance on these research through the use of a brand new temperature-at-depth mannequin and incorporating extra correct time-dependent and weather-dependent simulations of the EGS undertaking life cycle, in addition to an in depth EGS life cycle simulator known as Versatile Geothermal Economics Modeling (FGEM).
Two drilling price situations have been thought of – a baseline state of affairs, and a complicated drilling state of affairs that accounts for the improved efficiency in drilling charges noticed in current EGS tasks.
The EGS provide potential was estimated with respect to capital value and the levelized value of electrical energy (LCOE), with due consideration for the optimum depths required to maximise the financial outlook of EGS and seasonal era variability of versatile operations.
Modeling parameters and assumptions
Techno-economic evaluation was achieved by assuming that a number of unbiased tasks will exploit the EGS useful resource, every one occupying an 18 km3 lease (18 km2 areal extent and 1 km thickness). FGEM was used to simulate the life cycle of EGS vegetation, in addition to versatile geothermal operations by wellhead throttling and energy plant bypass.
Primarily based on profitable EGS implementations, the mannequin thought of an EGS programs as consisting of doublets of horizontal manufacturing and injection wells every with a 2000-meter lateral part accomplished with 9.625-inch casing string. Every doublet was set to occupy a hydraulically stimulated reservoir with 1.16 km3 bulk quantity and 10% porosity, and a complete of 16 doublets will fill every 18 km2 grid cell. Every nicely was set to move 125 kg/s.
Solely assets with temperature-at-depth of 150 °C or increased have been thought of as being techno-economically important for energy era. Assets spanning depths of 1-7 kilometers throughout the contiguous United States have been thought of. Energy era was achieved utilizing Natural Rankine Cycle (ORC) energy vegetation, and every EGS undertaking had a lifetime of 25 years.
EGS potential estimates
The research estimated a complete gross EGS capability potential of 245,032 GW, considerably larger than the latest estimates of 7469 GW by Augustine et al. Though the estimated EGS energy potential is massive, you will need to observe the quantity that may be economically produced is prone to be a lot smaller. It is usually vital to notice that 78% of that potential was at depth of 6–7 km, the place subsurface temperatures have been considerably excessive in comparison with shallower depths.
Nearly all of EGS internet era potential per unit space is within the Western and Southwestern areas of the US. After excluding delicate land, California confirmed the best capability potential for EGS, with a complete capability potential of 20,882 GW. Oregon, Nevada, Montana, and Texas adopted in rank with comparatively excessive potential of 18,270, 16,484, 15,681, and 14,578 GW, respectively.
Techno-economics of EGS
The research evaluated the financial viability for every 18 km3 EGS undertaking primarily based on capital expenditure (CAPEX), operational expenditure (OPEX), and era over time, which have been represented by way of LCOE with a reduction price of seven% and funding tax credit score (ITC) of 30%.
Contemplating the business-as-usual (BAU) state of affairs of baseload dispatch and baseline drilling charges, the research discovered that LCOE was minimized by drilling to the deepest level (7 km) for 89.3% of the US areal extent. In the meantime, drilling to depths of ? 4 km was discovered optimum solely throughout 0.27% of the US areal extent, primarily round Western United States.
Superior drilling charges resulted in 24.3% LCOE enchancment, on common, the place the baseline and superior situations resulted in common LCOE of 86.1 and 63.4 USD/MWh, respectively.
Contemplating the BAU state of affairs of baseload dispatch and baseline drilling prices, a complete of 93,176 GW EGS useful resource capability was obtainable with LCOE under that of the common geothermal PPA pricing. In comparison with LCOE estimates of hydrothermal and biomass assets, the research estimated a complete EGS useful resource capability underneath BAU state of affairs of 82,945 GW and 155,821 GW, respectively. The research additionally estimated that whole EGS useful resource capacities of 0.65 GW have been economically possible in comparison with the marginal LCOE of photo voltaic PV, however no EGS assets have been discovered viable in comparison with onshore wind by way of LCOE.
The research additionally discovered {that a} 6.36% common discount in LCOE throughout EGS assets may be achieved by implementing versatile operations the place energy output was assorted to maximise energy era over the undertaking lifetime. Beneath this state of affairs, the research estimated whole versatile EGS useful resource capacities of 189,667 GW and 46.16 GW that have been economically possible contemplating the marginal LCOE of biomass and photo voltaic PV, respectively.
