The real excitement in the geothermal sector comes from the development of unconventional geothermal systems. These systems are not limited by the geographical constraints of traditional geothermal and can potentially access geothermal power from resources previously considered unrecoverable due to rock type or location.
Enhanced Geothermal Systems (EGS)
Enhanced geothermal systems have been developed since the 1970s to improve the permeability of geothermal systems through hydraulic, chemical, and thermal stimulation. This technology allows access to high subsurface temperatures in areas with low rock permeability or lacking a natural water source. By injecting high-pressure water into these formations, engineers can create fractures that allow for the circulation of fluids and heat extraction. This technique has the potential to increase the number of viable geothermal sites worldwide dramatically.
EGS utilize technologies pioneered by the oil and gas sector, such as directional drilling, hydraulic fracturing, and reservoir stimulation. These techniques enable access to deeper and hotter rock formations, significantly expanding the potential for geothermal energy production. The U.S. National Renewable Energy Lab estimates an EGS resource has the potential of over 5,000 gigawatts in the US alone, more than 400% of total U.S. electricity generation. To support this forecast, the U.S. Department of Energy (DOE) launched Enhanced Geothermal Shot™ in 2022 to help bring EGSs to America nationwide. The initiative aims to reduce the cost of EGS by 90% to $45 per megawatt hour by 2035, aiding in the transition to a clean energy future while also creating job opportunities and economic prospects in the US.
Advanced Geothermal Systems (AGS)
Advanced geothermal systems take the concept of geothermal energy extraction a step further. AGS utilizes deep, large, artificial closed-loop circuits where a working fluid circulates and absorbs heat from subsurface rocks through conductive heat transfer. The fluid is heated without direct contact with the hot rock, and the heat is then brought to the surface for direct heating or electricity generation. This approach eliminates the need for reservoir stimulation, reducing the risk of induced seismicity and lowering water consumption.
Geothermal Oil and Gas Hybrid Systems
The oil and gas industry's expertise and infrastructure are proving valuable in advancing geothermal energy production. Companies are exploring ways to repurpose existing oil and gas wells for geothermal energy extraction. These systems utilize geothermal fluids from existing wells to extend the life of the well, deliver energy savings, and reduce greenhouse gas emissions. It's a perfect example of how oil and gas infrastructure can be repurposed for renewable energy production.
While the potential of geothermal drilling is enormous, it's not without its challenges. Here are some key considerations:
High-temperature drilling: Geothermal wells often need to be drilled to 7-10 km depths to reach fluid at temperatures high enough for electricity production. This deep drilling in high-temperature environments presents unique technical challenges that require drilling at faster rates of penetration (ROP), demanding advanced machinery/tools and operators with the right level of aptitude.
Economic viability: The initial costs of geothermal projects can be high, particularly for enhanced geothermal systems. In a publication by the International Renewable Energy Agency (IRENA), the global installed costs for geothermal plants fall between 1,870 and 5,050 USD per kW. They can exceed the latter depending on site conditions. These substantial investments, coupled with the inherent risks of subsurface exploration, can deter potential investors and slow the growth of the geothermal sector. However, once operational, geothermal plants have low operating costs and can provide energy for decades.
Seismic concerns: Some enhanced geothermal techniques, particularly those involving hydraulic fracturing, have raised concerns about induced seismicity. The scientific community is still divided on the extent of this risk.
Regulations: The current regulatory environment poses significant barriers to rapid innovation and deployment. Permitting processes for geothermal projects, particularly on federal lands where many resources are located, can be lengthy and uncertain. This uncertainty adds to the overall project costs and can discourage investment in geothermal drilling and development.
If you are also interested in the development and utilization of geothermal wells, please do not hesitate to contact us to get the full support of the Vigor team.
For more information, you can write to our mailbox info@vigorpetroleum.com & marketing@vigordrilling.com
