What is the difference between Conventional and Engineered Geothermal Systems?
Both Conventional and EGS make
use of naturally occurring heat
to produce power. Conventional
Geothermal Systems are associated
with areas of volcanicity, such as
Iceland, New Zealand and USA.
Characteristically these systems are
defined by their high temperatures,
relatively shallow depth and degree
of natural permeability and flow.
In contrast EGSs are located in areas
where radiogenic granites have
resulted in anomalously high crustal
heat flows. In order to trap the heat
generated a thick sedimentary
sequence is required to act as an
insulting blanket. Sediments such
as shale and coal beds have a
low thermal conductivity and as
a result higher temperatures are
achieved. EGS resources are typically
lower temperature resources than
conventional volcanic systems, and
by nature, are located at deeper
depths. As with conventional systems,
permeability varies, but some
engineering of the geothermal
reservoir is usually required.