Geothermal energy, despite vast potential, still accounts for just 0.4% of net electricity generation in the United States. The total energy content of the heat stored within the Earth’s core is immense but geothermal power plants are currently connected with high upfront costs. Can this situation change in years to come?
Many geothermal energy proponents claim that the answer could be found in deep geothermal drilling that could provide more than enough clean energy to meet the world’s needs.
The deeper the drilling goes, we go to the temperatures where water becomes supercritical, and thus provide large improvement in the power production per well and so cheapen the cost of energy.
The deepest hole that’s been drilled to date, the Kola borehole in Russia, is 7.6 miles deep. It took 20 years to complete because conventional equipment like mechanical drill bits break down at those depths. What this means is that geothermal industry needs better drilling technology.
One of the most interesting technologies that is being currently developed involves using microwaves to blast rocks. Scientists developed the general technique at MIT over the last decade, and proved that microwaves could actually drill a hole in basalt. The gyrotron machine that produces the microwave energy has been used for around 70 years in nuclear fusion research.
This technology could be ideal for the hard, hot, crystalline rock deep down that conventional drilling struggles with and since microwaves are not as efficient in the softer rock closer to the surface, that conventional drilling excels at, the hybrid system including conventional drilling and microwaves.