Development and techno-economic analysis of an innovative U-shaped geothermal system with artificial geyser

Geothermal energy from hot dry rock is a sustainable energy source with vast reserves in the Earth's crust. Open-loop geothermal systems can extract geothermal energy on a large scale but pose serious environmental problems, whereas closed-loop systems with multiple branches for enhanced heat extraction performance suffer from high pumping power consumption. This study proposes an artificial geyser U-shaped geothermal system to address prior limitations of common closed-loop systems. The flashing chamber design realizes natural circulation to reduce investment and operational costs. A validated numerical model shows that a well of 5 km depth and 0.06 K m−1 temperature gradient can generate up to 1.4 MW of power by the steam turbine, while 50–400 kW by the thermoelectric generator, depending on geothermal gradients and cold-side fluids. By retrofitting abandoned oil and gas wells to significantly reduce the drilling costs, the system's levelized cost of electricity is $0.1 kWh−1 at a turbine power output of 700 kW. The discounted payback period is 15 years when the electricity price is $0.2 kWh−1. The above results show that this system offers a good balance between capacity and cost-effectiveness. This work advances geothermal energy development through sustainable, low-carbon, and low-risk pathways.