Measures of Central Tendency: Mean, Median and Mode
Geothermal Areas in Turkey
1. ENVIRONMENTAL IMPACT OF THE
UTILIZATION OF
GEOTHERMAL AREAS ıN TURKEY
Prof.Dr. Alper BABA
Izmir Institute of Technology
Geothermal Energy Research and Application Center
alperbaba@iyte.edu.tr
2. WHAT IS GEOTHERMAL ENERGY?
A clean, renewable and environmentally benign energy
source based on the heat in the earth
Used in 58 countries of the world. Known in over 80
Electricity generation in 24 countries
Direct heating use in 78 countries
3. APPLICATION OF GEOTHERMAL
RESOURCES
Geothermal resources have long been used for
direct heat extraction for district urban heating,
industrial processing,
domestic water and space heating,
leisure and balneotherapy applications.
Geothermal fields of natural steam are rare, most being a mixture
of steam and hot water requiring single or double flash systems
to separate out the hot water, which can then be used in binary
plants or for direct heating.
Re-injection of the fluids maintains a constant pressure in the
reservoir, hence increasing the field’s life and reducing concerns
about environmental impacts
4. GEOTHERMAL ELECTRICITY
INSTALLED CAPACITY MWE (2013)
Russia 82
Iceland 575
Italy 843
China 24
USA 3093
Turkey 243.35
Japan 536
Mexico 958
Guatemala 52
El Salvador 204
Costa Rica 166
Guadeloupe 4
Philippines 1904
Ethiopia 7.3
Kenya 167
Indonesia 1197
Australia 1.1
New Zealand 437
5. GEOTHERMAL DIRECT USE
ENERGY PRODUCTION GWH/YR (2010)
Canada 2465
Mexico 1117
USA 15710
Guatemala
El Salvador
Costa Rica
Sweden 12584
Germany 3546
Latvia
Switzerland 2143
Lithuania
Poland
Russia 1707
Ukraine
Iceland 6767
Mongolia
Slovakia
Romania
Bulgaria
China 20931
Serbia
Georgia
Macedonia
Nepal
Japan 7139
Tunisia
Greece Turkey 10247 Iran
Algeria
Guadeloupe
Pakistan
Egypt
Eritrea
Uganda
Jordan
Djibouti
Ethiopia
Kenya
Thailand
Vietnam
Philippines
Indonesia
Burundi
Tanzania
Australia
New Zealand 2654
7. TURKEY
Turkey is one of the most seismically active regions in the world.
Its geological and tectonic evolution has been dominated by the
repeated opening and closing of the Paleozoic and Mesozoic oceans
(Dewey and Sengör, 1979; Jackson and Mc Kenzie, 1984).
It is located within the Mediterranean Earthquake Belt, whose
complex deformation results from the continental collision between
the African and Eurasian plates (Bozkurt, 2001).
The border of these plates constitutes seismic belts marked by
young volcanics and active faults, the latter allowing the
circulation of water as well as heat.
The distribution of hot springs in Turkey roughly parallels the
distribution of the fault systems, young volcanism, and
hydrothermally altered areas
10. More than 1000 hot
spring can be seen in
Turkey
MTA, 1995, Şimşek, 1982, 2010
11. Geothermal Resources in
Turkey
More than 1000 hot spring can be seen in
Turkey. Temperatures ranging from 25°C to
as high as 287 °C, fumaroles, and numerous
other hydrothermal alteration zones.
18. ENVıRONMENT PROBLEMS
Turkey is one of the fastest growing power markets in the world
and is facing an ever-increasing demand for power in the coming
decades
Geothermal development over the last forty years in Turkey has
shown that it is not completely free of impacts on the environment
24. SCALING AND CORROSıON
Turkish geothermal operators claim to have virtually overcome the consequences
of scaling and corrosion in both high and low temperature wells (Demir et al., 2013;
Geothermic)
25.
26. GEOTHERMAL FLUIDS ENCOUNTERED
IN TURKEY CAN BE CLASSIFIED
CHEMICALLY AS %95 INCRUSTING
AND TWO TO THREE GEOTHERMAL
FIELDS HAVE HIGHLY CORROSIVE
GEOTHERMAL FLUIDS.
IN THREE OF THE 140 GEOTHERMAL
FIELDS, GEOTHERMAL FLUID
CONTAINING TOTAL DISSOLVED
SOLIDS (TDS) EXCEEDS 5000 PPM.
Turkish geothermal
operators claim to have
virtually overcome the
consequences of scaling
and corrosion in both high
and low temperature wells,
and scientific research.
27. GEOTHERMAL FLUID COMPOSITIONS
The
vast majority of geothermal fluids is
of meteoric origin.
However,
isotopic studies suggest that a
small fraction (5-10%) may emanate from
other sources, magmatic, juvenile, fluids
or host sediments (connate or formation
water)
Most
geothermal fluids exhibit higher
TDS contents than the original, cooler,
intake waters.
28. GEOTHERMAL FLUID COMPOSITIONS
The amount and mature of dissolved chemical
species depend on temperature, pressure,
minimal-fluid equilibria and mixing with other
waters.
One may logically infer that hotter fluids would
display higher TDSs than cooler ones, an
attribute however suffers many exceptions.
29. THE MAJOR CONSTITUANTS
OF GEOTHERMAL
WATERS ARE;
Cations:
Na, K, Ca, Mg, Li, Sr, Mn, Fe
Anions: Cl-, HCO3-, SO42-, F-, Br Non ionic: SiO2, B, NH3, gases
Minor constituants: As, Hg, heavy, often
toxic, metals
30. Corrosion and Scaling
Damage occurs under the form of metal corrosion and
deposition on exposed material surfaces of scale species.
Both phenomena may also coexist through deposition
and/or entrainment of corrosion products.
Most commonly encountered damages address CO2/H2S
corrosion, alkaline carbonate/sulfate, heavy metal
sulphide and silica scale.
Source mechanisms are governed by pH, solution gases
and related bubble point and (CO2) partial pressures,
salinity, solubility products and of thermodynamic
changes induced by the production and injection
processes.
31. CORROSION AND SCALING
Whereas scaling affects mainly high enthalpy systems,
a result of fluid flashing,
steam carry over and injection of heat depleted brines,
corrosion and, at a lesser extent though,
corrosion is the major damage in exploitation of low
grade geothermal heat, known as direct uses.
Micro-biological activity, particularily sulfate reducing
bacteria, can also be a significant corrosion contributor
in such low temperature environments.
33. CALCIUM SCALE INHIBITION
Four inhibition groups
i. Threshold effect: the inhibitor acts a as salt
precipitation retarder.
ii. Crystal distortion effect: the inhibitor interferes
with crystal growth by producing an irregular
structure (most often rounded surfaces) with weak
scaling potential.
iii. Dispersion: the polarisation of crystal surfaces
results in the repulsion between neighbouring crystal
of reverse polarities
iv. Sequestration or chelation: complexation with
selected cations (Fe, Mg, etc…) leads to the formation
of soluble complexes.
37. CORROSION/SCALING
MONITORING PROTOCOLS
hydrodynamics: control of pressures and temperatures and
subsequent well, reservoir, geothermal network and heat exchanger
performances,
fluid chemistry: general and topical (selected indicators, HS-, S2-,
Fe3+, Fe3+, Ca2+, HCO3-, etc.) liquid and PVT (dissolved gas phase,
gas-to-liquid ratio, bubble point) analyses,
inhibitor injection concentrations: volume metering, flow
concentrations via tracing of the inhibitor active principle,
solid particle monitoring: concentrations (staged millipore
filtrations) and particle size diameters and distributions (optical
counting, doppler laser velocimetry),
microbiology: sulphate reducing bacteria numbering,
corrosion: measurement of corrosion rates (coupons, corrosion
meters),
down hole line integrity: electrical measurements, pressurisation
and/or tracer tests,
periodic well logging inspection
38. DEPOSITION STUDY
Themodynamics. Theory
Kinetics. Practice
In line coupons
Solids
Ageing. Laboratory simulation (Bench scale study)
Suspended tank
Full scale simulation
40. SILICA SCALE
EFFECT
Problematic in surface equipment and in connection with
disposal
Thermodynamic study to determine minimum temperature of
possible deposition
Bench scale study prior to ponding or re-injection to study rate under
different conditions
41. SILICA REMOVAL/CONTROL
l
Prevention:
– t > tAS
– Inhibitors, e.g hydroxy-ethyl-cellulose, ethylene
oxide, -C-O-C- group compounds
l
Removal: Difficult
– Physical: drilling, scraping, hydroblasting,
cavitation descaling
– Chemical: HF, hot NaOH; undesirable
42. IRON SILICATES (OXIDES, CARBONATES)
In high temperature brines, e.g Tuzla, Salton Sea,
Djibouti, Milos. Also where volcanic activity has
interfered, e.g Centreal and Eastern Anatolia
Temperatures at least 50°C higher than for formation
of simple silica deposits
Proposed mechanism:
OFeOH•H2O + Si(OH)4 Fe(OH)3•SiO2 + 2H2O
When formation starts extent is great
43. IRON COMPOUNDS: Fe/Si RATIO,
CONTROL AND REMOVAL
Fe/Si RATIO (mole/mole):
0.15
at 105°C, 1.00 at 220°C (Tuzla)
Control and Removal
Pressure
control
Acid
Reducing
agents, e.g. Na formate, as
inhibitors
Drilling out
44. SULPHIDES
PbS (galena), ZnS (sphalerite), CuS covellite), Cu2S
(chalcocite), SbS2 (stibnite, in Mt Amiata, Italy),
CuFeS2 (chalcopyrite), FeS2 (pyrite), FeS (pyrrhotite)
by reaction of metal(s) with H2S.
Saline solutions, effect of volcanic gas
Lower temperature lower solubility
Milos: Not directly on metal. Order of scales from
wellhead to outflow: Galena, sphalerite, Fe-Si, SiO2
46. Deposition at different pressures
Branched line
Pressure controlled by orifices.
Coupons inserted after each orifice
Flow regulated by RJ-pipes,
critical lip pressure monitored
Pictures from Haldor Arrmansson
48. CALCITE SCALING
Flashing CO2 stripping and pH increase,
causing calcite deposition
Ca+2 + 2HCO3- CaCO3 + CO2 +H2O
Increasing temperature decreasing solubility
Extent of supersaturation can be calculated
49. CALCITE
Removal
Drilling out
HCl treatment
Control
Inhibition:Organic phosphonates (success claimed);Synthetic polymers
(e.g. polyacrylamide); Organic polymers (e.g. polycarboxylic acids);Sequestering
agents (e.g. EDTA, polyphosphates (successful in low temperature situations));
HCl: Success claimed but care needed
50. MAGNESIUM SILICATES
Formed upon heating of silica containing ground water or
mixing of cold ground water and geothermal water
Form at relatively high pH
Well known where
geothermal water used to
heat groundwater
Avoid mixing and keep pH
low
51. CORROSIVE SPECIES
O2: at low temperatures; H+ (pH): Low pH favours
cathodic half-reaction; Cl: Fe+2 + Cl- FeCl+
favours anodic half-reaction; CO2: Controls pH and
favours last cathodic half-reaction. H2S attacks Cu,
Ni, Zn, Pb
H2S, CO3-2 and SiO2 may form protective films on
steel
Fe+2 + HS- FeS + H+
Fe+2 + H3SiO4- FeSiO3 + H+ + H2O
Fe+2 + HCO3- FeCO3 + H+
53. MONITORING AND CONTROL
COUPONS
Wellhead
fluid
Two phase flow lines
Flashed liquid
Steam
Condensate
Cooling water
KEEP OXYGEN OUT
INSULATE Cl-RICH DRY STEAM
54. SPECIMENS
Type
Coupons
U-bend
specimens
Notched specimens
Fatigue specimens
Number
Vendor
of installation, plant owner,
contractor 1 set each
Test period. ½ year, 1 year, long-term: 1
set each
61. Result and Conclusion
Geothermal development in the last forty years has shown that
it is not completely free of adverse impacts on the environment.
These impacts are causing an increasing concern to an extent
that may now be limiting development
The scarce data available shows that the thermal fluids
contain trace elements (As, Cd, and Pb), which may affect soil
and water.
Corrosion and Scaling still a big problem in the most
geothermal fields.
All possible environmental effects should be clearly identified,
and mitigation measures should be devised and adopted to
avoid or minimize their impact.
