Geothermal energy - Some points to consider
by Patali CHAMPIKA RANAWAKA
 The
announcement made in April 2002, to inform that Velupillai Prabhakaran
was to hold his maiden national and international press conference in
Mallavi, Vanni to mark the so-called Prabha-Ranil peace accord was
itself some sort of a headline news to many local and foreign media.
However, it was ironic that Udaya Gammanpila and myself to have visited
Vavuniya, on the very day that Prabhakaran had his famous press
conference at which he was subtly unfolding his grand plan for a Tamil
Eelam.
Having travelled along Medawachchiya-Trincomalee road, we reached
Kinniya on the following morning, where the world famous Hot-wells are
located. At first sight, we were very happy to notice the presence of
large and active crowds in the vicinity of the Hot-wells.
However, our happiness quickly evaporated when we saw that LTTE
agents were charging a gate fee from the visitors to visit the
Hot-wells, a natural resource in our own country. When we looked around
further, to our dismay, we observed that the sacred Bo tree which was
there for many years has been cut down and old statues venerated by
Buddhists being destroyed. It was evident that ethnic and religious
cleansing was effectively taking place there, under the pretext of
so-called peace. What we saw around us, catalyzed me to swear to myself
that before long we should liberate not only our natural resources and
our national heritage around the area, but the entire country and the
people from the clutches of Velupillai Prabhakaran. We are happy now to
see that our country being fully liberated and are proud for the
contribution we have made to preserve its unitary character, once again.
On our return, Udaya who is always inquisitive and eager to learn,
wanted to know the physical theory behind the Hot-wells in Kinniya. I
explained to him about the high temperature molten metal core inside the
earth and as to how it causes water bodies which warms up in certain
areas of the earth. I enlightened him about the oceanic heat patch
identified from Mulathivu to Verugal area and also about the technology
called Ocean Thermal Energy Conversion or OTEC to convert Geothermal to
Electricity energy. I can still remember, during our University days,
two decades ago as to how our Power System Professors were arguing on
this particular subjects - prospects of Geothermal Energy as our
alternate energy. It is noted that now many countries in the world,
specially the USA are generously funding the research and development
work on tapping this enormous energy source.
Once, I heard that the US Ex Vice President Al Gore, quoting the
Massachusetts Institutes of Technology, having said that in 2006, it had
been estimated that technically extractable quantity of US Geothermal
resource was about 2000 times the annual consumption of the primary
energy source of the USA. It was a clear manifestation of the fact that
if they had succeeded, there would not have been any energy problem in
USA for two millennia.
It is true that Geothermal potential is so high and effectively
unlimited. Two experts in this field, Bruce Green and Gerald Nix says
that "the energy contents of domestic Geothermal resources which runs to
a depth of three kilometers is estimated to be three million quads -
equivalent to 30,000 year supply of energy at current rate in the USA.
According to the UN world energy assessment report the Geothermal
resource is approximately 280,000 times the annual consumption of
primary energy in the world. So, whatever way it is being accounted, it
would be the largest energy reserve the entire human beings have and is
larger than the combined resource potential of fossil fuel and renewable
resources such as solar and wind.
 In
order to understand Geothermal energy we should understand the inside of
the earth. According to the Geologists, the inner core of our earth is
made up of iron and its temperature is estimated to be between 8000 to
120000F which is as same as the temperature at the surface of the sun
and the outer core comprises of molten metal of which the temperature is
between 6700 - 80000F. Therefore, the enormous heat so generated inside
the earth is naturally transmitted to the earth mantel and to the outer
crust by convention and conduction.
It is widely assumed that this outer crust runs to an average depth
of 30 kilometers and the crust itself generates heat causing its
contained radio active metal to decay. The Geologists are of the opinion
that within a depth of 10 kilometers of the outer crust of the earth
there contain 60,000 times as much energy as all the petroleum and
natural gas resources in the world.
This enormous inside heat sometimes comes out to the earth surface
through the earth fault lines or weak earth structures and as a result
we could naturally find very hot geological areas and hot water bodies
like in Kinniya-Trincomalee.
Geologists have already identified two kinds of geological heat
areas. One is in and around the areas where earth tectonic plates meet
each other.
It is believed that the earth's other crust is made out of floating
tectonic plates and the inner heat could come out along their
boundaries. The scientists also have identified what they call the ring
of fire, a hot zone around the Pacific Ocean from New Zealand -
Indonesia - China - Japan - Alaska - North America and to South America
lying parallel to the boundaries of tectonic plates. The other kind of
heat areas are the earth's Hot-Spots.
They are available around the world and may have come to being due to
volcanic activities or other geological activities. The scientists are
now able to clearly map out these Hot regions and their energy
potential. Although, Sri Lanka does not possess any of the above
Hot-Zones it has high temperature gradient area around it.
One explanation given for the existence of these Hot-Spots is that
some asteroid or space motor had caused earth core heat to surface in
earth's crust.
It is like that when some space matter which is large enough to make
waves collide with the earth curst the shock waves so created could
travel through earth's core to the diametrically opposite side of the
earth.
This pushes the melted metal core and other heated metals to move
towards the other side of the earth causing Hot-Spots. Whatever the
explanation attributed for the existence of Hot-Spots, they are warm
enough to generate heat and electricity. The next question is to know as
to how we could tap this valuable energy source.
This mechanism could be described as follows: After having identified
the Hot Zone, sometimes several kilometers deep into the earth, wells
are drilled. For this purpose generally there are twin wells where one
is used to pump down the cool water and the other to pump back the
heated water which is being heated when it goes through Hot Rocks or Hot
Zones inside the earth. Thereafter, the heated water or liquid is used
to drive the turbine which propelled the generator and produce
electricity.
This general mechanism has now been enhanced and is called Enhanced
Geothermal System or EGS. When we use the same technique to convert
oceanic heat into electricity we called it Ocean Thermal Energy
Conversion or OTEC.
Generally, some industrialized countries with Geothermal potential
are using this energy for their heating and cooling purposes. New
Zealand was the first country to introduce thermal energy - the Wivekei
power station in New Zealand produces 180 mega watts of electricity
using Geothermal energy. In California - USA, 22 Geothermal plants are
now in operation making it, perhaps the largest Geothermal installation
in the world. Japan, Iceland, Australia, France and Germany etc, are the
other countries which use Geothermal energy for generating electricity
for heating and cooling purposes.
Geothermal energy has many advantages. Firstly, as it does not emit
carbon dioxide it is basically considered to be clean energy.
Secondly, its constant supply of energy, unlike wind or solar which
are heavily dependent on weather and time conditions could be used as a
major base load energy source like coal or oil without any pollution.
Thirdly, if Research and Development could enhance the utility value
of the Geothermal energy, it could simply replace fossil fuel as our
main source of energy as it's potential is estimated to be so large. Due
to these encouraging factors, the so-called industrialized countries are
now aggressively taking steps to use Geothermal energy as a major
option.
However, when going into these options, countries have to overcome
many constraints of which its cost problem being the worst. It has been
estimated that to drill a single hole to a depth of three kilometers it
costs 5 million US$ or more and it is similar to drilling an oil well.
It is a random process where sometimes one may not be successful in
producing heat. Could scientists be able to overcome the uncertainty
associated with its drilling process and lower the high cost involved?
Some are optimistic like Ex US Vice President Al Gore, who is already
using Geothermal energy for heating and cooling facilities in his house.
They use ground heat to produce heating, cooling and hot water to
their house. Would it be an alternative energy source to our country as
well. Although, we do not have Hot-Spots and Hot regions which could
produce substantial energy, we also should research into the available
Geothermal potential in Sri Lanka. Our Geologists and our Geological
Survey and Mines Bureau, has identified 10 high gradient temperature
locations which could produce Geothermal energy.
However, we need more attention, investment and research into this
new field.
(The writer is the Minister of Environment and Natural Resources)
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