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ABSTRACT: Extraction of the energy available from geothermal heating in the Earth could provide substantial contributions to energy needs long-term. However, there are major technical limitations with the current geothermal drilling process. A new technology in the field of EGS that uses a millimeter (mm) wave gyrotron, which allows for quicker, more efficient drilling could be a potential way to overcome these limitations. The mm-wave drilling process, a technique developed by Dr. Paul Woskov of the MIT Plasma Lab, has two significant advantages as compared to traditional drilling: 1. The well hole advance is through melting of the rock, which is faster than mechanical drilling. 2. The molten rock then solidifies, creating a vitrified wall support without the need for extra casings. This drilling and casing process can potentially save money, time, and material. The study presented in this paper is aimed at understanding the strength and microscale mechanical and chemical properties of the vitrified material to see what is happening to the rock, specifically Basalt, pre- and post-melting by using a series of experimental and analytical tools. 1. INTRODUCTION With global energy consumption on a continual upward slope, there is a growing need for a clean and renewable energy solution. At present, in the United States, geothermal energy constitutes merely 2% of the total renewable energy usage. However, both in the U.S. and globally, the utilization of geothermal energy has been steadily increasing. Tapping into the Earth's heat potential holds the promise of significantly reducing CO2 emissions and making substantial contributions to meet the escalating energy demand worldwide. Nevertheless, significant limitations currently impede the feasibility of this approach in the United States, creating the necessity of alternative methods. Thanks to researchers at the MIT plasma lab, a novel approach was introduced: the utilization of a millimeter – wave (MMW) gyrotron. This technology potentially allows one to drill wells by employing MMW heating, leading to the melting and vaporization of basement rock at extremely high temperatures. The rapid heating and subsequent cooling of the rock result in the formation of a glass-like substance, making it possible for this vitrified material to serve as a wellbore casing for geothermal injection and production wells.
Meltzer et al. (Sun,) studied this question.