hole walls are of glass of surrounding rock. Cost decreases with depth, with no limit on depth of bore hole. Bore diameters from 1m to 10m. Recovery of energy used to melt rock. 8. Gyrotron - Millimeter-wave microwaves are channeled using a waveguide to vaporize rock. High-energetic electrical plasma One of the most promising approaches in deep drilling field is utilization of electrical plasma. It has lower energy efficiency than some of the other technologies, but it has several other advantages. Producing boreholes with wide range of diameters or drilling in water environment can be mentioned. The research team from Slovakia has developed drilling concept based on utilization of electrical plasma. The core of the research is held in Research Centre for Deep Drilling which was opened in the premises of Slovak Academy of Sciences. Only a very small number of companies have embraced this method, e.g. GA Drilling, headquartered in Bratislava, Slovakia. Advantages of Plasma deep drilling technology Higher drilling energy efficiency Continuous drilling process without replacement of mechanical parts Constant casing diameter Effective transport of disintegrated rock State of the art No one as of yet has proved the effective use of these techniques in severe conditions. Other complications including on site energy and material transport from 5 to 10 km bores also require refinement to become both technically and economically feasible. See also Plasma deep drilling technology Drilling rig Enhanced geothermal system Geothermal energy Oil well Geothermal Anywhere Quaise References Massachusetts Institute of Technology (2006) "The Future of Geothermal Energy" Pierce, K.G., Livesay, B.J., Finger J.T. (1996) "Advanced Drilling System Study" Ikeda, K., Satoh, T., Yoshikawa, M., Kurosawa, T.(2000) "Development of laser associated cutting method for dangerous rock slopes" "Proposed New Deep Bore Technology" Parkview Press (2011) Drilling technology Geothermal drilling Geothermal energy Mining engineering