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Recent theoretical studies dealing with the novel scheme for earth-deep hot dry rock geothermal energy extraction based on the use of a super-long heat pipe indicate its superior technical viability. The present work reports on a field test using a 3000-m heat pipe to extract hot dry rock geothermal energy conducted with the aim of demonstrating its practical feasibility. The in-house developed heat pipe uses deionized water as working fluid and produces steam with a maximum temperature of ∼90 °C, when the average underground formation temperature around the subsurface heat pipe is 95.6 °C. During the 30-day continuous heat mining process, the heat extraction rate achieved an average value of 190 kW with no obvious downward trend. After one month of continuous heat production, a one-week heat recovery can restore the system temperature to just slightly lower than the initial value. The thermal …