Geoscience Reference
In-Depth Information
Yi
component
Yi
component
Yi component
Injection
Product
Product
Product
Hot water
Hot water
Extraction of
Xi component
Hot water
Hot water
Artificial
fracture zone
Natural
fracture
zone
Natural
fracture
zone
(a)
(b)
(c)
Figure 1.2 Geothermal reactors for mineral synthesis
[82]
.
Similarly, enhanced geothermal systems (EGS) are available in several countries.
These EGS are renewable energy and provide better understanding of hot rock
fluid
interactions, through more realistic simulations that mimic extreme conditions not
currently achievable with other systems
[83]
.
The main disadvantage of the geothermal reactor is that the flow characteristics
of high-temperature slurry accompanied with the chemical reaction must be well
understood for controlling the reaction. The volumetric capacity of the geothermal
reactor is very large compared to that of usual autoclave, and the operation must be
continuous. The merit of the geothermal reactor and its cost of operation can be
realized only if the target material is to be developed in large quantities.
1.7 Submarine Hydrothermal Systems
The general acceptance of plate tectonics theory some 2
1
2
decades ago has garnered
much interest in geochemical processes at plate boundaries which has led to the dis-
covery of hydrothermal activity in the deep sea directly on the Galapagos Spreading
Centre in 1977
[84]
and a large number of other spectacular submarine hydrothermal
systems (like the Red Sea Rift Valley, Juan de Fuca Ridge-North Pacific Ocean; 21
N
East Pacific Rise, Kamchatka, Kurile Islands, Atlantis II Deep in the Red Sea, Lake
Kivu, Lost City hydrothermal field, and so on) of global significance to ocean chemis-
try and geochemistry
[85]
. The global distribution of known hydrothermal vents is
shown in
Figure 1.3
. The studies related to the temperature and chemical anomalies
of these hydrothermal vents hint that many more sites exist throughout the world's
oceans. In fact, this discovery has led to a new thinking in marine biology and geo-
chemistry, and in economic geology and has spawned an entirely new term, viz.,
