Self-test questions: Chapter 10

Self-test questions: Chapter 10

. The centre of the Earth is very hot. What proportion of the heat flow at the Earth's surface is due to the decay of radioactive elements?

. Many geothermal systems tap into underground aquifers containing hot water. What is the term describing the ability of rock to transmit water?

. What is magma?

. Water boils at 100°C at 1 atmosphere pressure. What is its boiling point at 50 atmospheres pressure?

. When high temperature geopressured brine is pumped from geothermal wells to the surface, it may boil to produce steam as its pressure is reduced. What is this process called?

. What working fluid is used to drive the turbine in an organic rankine cycle (ORC) geothermal power plant?

. A typical enhanced geothermal system might tap the heat in an underground volume of 1 cubic kilometre of rock. Cooling this volume through 1 degree celsius could provide the heat energy equivalent of burning how many tonnes of coal?

. How deep are the GPK2-4 boreholes at the Soultz-sous-Forets EGS site?

. What gas, which smells of rotten eggs, may be produced by geothermal wells?

. What proportion of Iceland's electricity demand was generated by geothermal energy in 2015?

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