Maximizing the Economic Yield of Geothermal Energy Extracted from the Magma-hydrothermal Interface by Combining Production of Electricity, Hydrogen, Minerals and Desalinated Water.
The Iceland Deep Drilling Project is testing the utilization of supercritical hydrothermal fluids developed in, and above, magmatic intrusions, because of their attractive enthalpy and transport properties. Supercritical geothermal wells should produce ten times more power than the usual subcritical geothermal wells. In 2009 the well IDDP-1 drilled into an aphyric, 900oC rhyolite magma at only 2.1 km depth that yielded superheated steam at a rate sufficient to generate 34 MWe. In 2017 the world's first supercritical well, IDDP-2, was drilled to 4.5 km depth, with bottom hole temperatures apparently 600oC and fluid pressures >35MPa. The advantages of supercritical production include: (1) Improvement in the ratio of the power output per well to drilling costs. (2) Improvement in the lifetime of existing geothermal fields by extending the producible resource downwards. (3) Improvement in the power conversion efficiency of turbines. (4) Improvement in the economics. Compared to other intermittent forms of alternative energy, geothermal electricity has the advantage of delivering base-load electricity. The geothermal industry could improve revenues by adopting a fully integrated approach that, in addition to electricity sales, gets revenue from the hot fluids produced. Where the conditions permit this can be done by selling electricity when demand is high and, when demand is low, using electricity to produce hydrogen by electrolysis of supercritical water. Electrolysis is more efficient at high temperatures, but electrolytic cells require clean water, so desalination would likely be necessary. Combining electrolytic H2 with hydrothermal CO2 to make methanol could be another source of revenue. Similarly, when the chemistry of the hydrothermal fluid is suitable, salable products such as lithium, base metals, and other mineral products could be extracted. The future of utilizing supercritical magma-hydrothermal energy will require improving the technology of drilling and completing wells that produce very hot and corrosive fluids. The incentive is the economic potential made possible by a fully integrated approach to enhance revenues. Developing magma-hydrothermal resources could be the next major advance in producing "green" energy.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- 1036 Magma chamber processes;
- GEOCHEMISTRYDE: 1037 Magma genesis and partial melting;
- GEOCHEMISTRYDE: 8424 Hydrothermal systems;
- VOLCANOLOGYDE: 8439 Physics and chemistry of magma bodies;