Excavation based enhanced geothermal system (EGS-E): introduction to a new concept

J. Zhao, C. A. Tang, S. J. Wang

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)

Abstract

The current technology for enhanced geothermal system (EGS) typically involves drilling of deep injection and production wells to inject cold water into the injection well to the EGS reservoir depth, to extract heat by permeating through the fractured hot rock masses, collected by the production well and return to the surface as heated water. In this article, a new approach is proposed to develop EGS based excavation technology (EGS-E). This method consists of (1) excavation to deep rocks, including a deep shaft from surface to the EGS depth, a room-and-pillar mined cavern complex to be filled with water to become a large underground heated water reservoir in the hot rocks; (2) enhanced heat extraction from rock, aided by additional drillholes spreading out and down from the caverns, and induced fracturing of the surrounding rocks for enhanced rock–water heat transfer; (3) enclosed heat transmission from heated water reservoir to the power plant by using independent heat conducting pipes running between them, continuously supplying the heat for power generation, without water movement in the reservoir. EGS-E offers the following advantages: (1) utilizing mechanized rock excavation technology for large volume energy production; (2) greatly increasing heat extraction volume by easily extending vertically and horizontally; (3) maximize the energy transfer from hot rock to the water reservoir; and (4) separated heat transmission from heated water reservoir in EGS to power plant to minimize environmental pollution.

Original languageEnglish
Article number6
Number of pages7
JournalGeomechanics and Geophysics for Geo-Energy and Geo-Resources
Volume6
Issue number1
DOIs
Publication statusPublished - Mar 2020

Keywords

  • Deep rock excavation
  • Enhanced geothermal system (EGS)
  • Heat transfer
  • Hot dry rock
  • Hot water reservoir

Cite this

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abstract = "The current technology for enhanced geothermal system (EGS) typically involves drilling of deep injection and production wells to inject cold water into the injection well to the EGS reservoir depth, to extract heat by permeating through the fractured hot rock masses, collected by the production well and return to the surface as heated water. In this article, a new approach is proposed to develop EGS based excavation technology (EGS-E). This method consists of (1) excavation to deep rocks, including a deep shaft from surface to the EGS depth, a room-and-pillar mined cavern complex to be filled with water to become a large underground heated water reservoir in the hot rocks; (2) enhanced heat extraction from rock, aided by additional drillholes spreading out and down from the caverns, and induced fracturing of the surrounding rocks for enhanced rock–water heat transfer; (3) enclosed heat transmission from heated water reservoir to the power plant by using independent heat conducting pipes running between them, continuously supplying the heat for power generation, without water movement in the reservoir. EGS-E offers the following advantages: (1) utilizing mechanized rock excavation technology for large volume energy production; (2) greatly increasing heat extraction volume by easily extending vertically and horizontally; (3) maximize the energy transfer from hot rock to the water reservoir; and (4) separated heat transmission from heated water reservoir in EGS to power plant to minimize environmental pollution.",
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Excavation based enhanced geothermal system (EGS-E) : introduction to a new concept. / Zhao, J.; Tang, C. A.; Wang, S. J.

In: Geomechanics and Geophysics for Geo-Energy and Geo-Resources, Vol. 6, No. 1, 6, 03.2020.

Research output: Contribution to journalArticleResearchpeer-review

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