ENVIRONMENTAL ASPECTS OF
GEOTHERMAL ENERGY USE IN HUNGARY
Csilla Tonkó, GyörgyPátzay
BME KKFT&MTET
6. May. 2011
RENEXPO 2011
Geothermal energy
•Geothermal energy is one of the cleanest, partially renewable energy.
•Conventional geothermal energy (100-2500m depth) can be used directly for
heating, drying stc. or indirectly for electric energy production.
•Geothermal fluids are multicomponent, multiphase fluids or steam, containing
dissolved solid, gas, organic materials and suspended solid particles. These
components
concentrations
vary
in
a
broad
scale.
•Concentration of the dissolved components are usually increasing with
temperature. Some components (toxic etc.) should be removed before or after
the energetic use.
•Potentially the components with high risk (Hg, B, As, and Cl) could be
separated, and the used fluid should be recharged into the reservoir.
2
Some geothermal wells are potentially suitable for
electric energy production (ORC) in Hungary
3
NSz-3
high
entalphy well
High TDS and
chloride, less
calcium- and
magnesium
bicarbonate and
sodium sulfate.
There is no
calcium-sulfate
and chloride
present.
parameters
values
unit
Depth of well
3165.0
m
Water flowrate
1313.4
dm3/min
Water temperature
171.0
oC
TDS
24855.0
mg/dm3
Gas flowrate
6986.1.0
dm3/min
Gas temperature
171.0
oC
Wellhead pressure
45.0
Bar
Separated GWR
1700.0
CO2 16.270 vol%,
CH4 79.440 vol%
N2
4.290 vol%
Ndm3/m3
Dissolved GWR
3400.0
CO2 35.250 vol%,
CH4 61.910 vol%
N2
2.840 vol%
Ndm3/m3
Water analysis
Ca2+ 1.335.10-3
Mg2+ 3.350.10-4
Na2+ 3.453.10-1
SO42- 2.380.10-4
Cl- 3.179.10-1
ATOT 2.600.10-2
mol/kg
mol/kg
mol/kg
mol/kg
mol/kg
mol/kg
4
Fab-4
high
entalphy well
High TDS and
chloride, less
calcium- and
magnesium
bicarbonate and
sodium sulfate.
There is no
calcium-sulfate
and chloride
present.
Parameter
value
unit
Depth of well
4239.0
m
Water flowrate
3750.7
dm3/min
Water temperature
180.0
oC
TDS
27200.0
mg/dm3
Gas flowrate
46500.0
dm3/min
Gas temperature
180.0
oC
Wellhead pressure
40.0
Bar
Separated GWR
4400.0
CO2 76.714 vol%,
CH4 20.899 vol%
N2
2.566 vol%
Ndm3/m3
Dissolved GWR
8000.0
CO2 89.300 vol%,
CH4 7.824 vol%
N2
3.876 vol%
Ndm3/m3
Water analysis
Ca2+ 3.081.10-3
Mg2+ 4.540.10-4
Na2+ 4.284.10-1
SO42- 2.380.10-4
Cl- 4.684.10-1
ATOT 1.009.10-2
mol/kg
mol/kg
mol/kg
mol/kg
mol/kg
mol/kg
5
Other possibilities:
Heat pump heating using geothermal heat.
Example: Szeged city . The building of the Environmental authority is heated. 15
drilled 120 m deep heat exchanger used.
District heating with geothermal wells using recharging wells into UpperPannonian sandstone in Hódmezővásárhely. Since 1998 the system is in
service.
The GeoGas Energia-hasznosító és Szolgáltató Co. developed a project to use
the separated methane content of 32 geothermal wells in gas engines to
produce electricity. The mathane content of these wells are between 65-95%.
The project contains future use of 27 gas engines (7 with 201 kWe, 10 with 150
kWe and 10 with 105 kWe capacity.)
6
Geothermal energy direct use has advantages:
Low- and medium-enthalpy fluids could be used (<150oC)
Theese fluids are the most of the fluids (80 countries)
In direct use no convection- high efficiency
Conventional drilling technology can be used
Conventional, not too expensive devices are needed (fitted on the
temperature and chemistry of the fluids)
• Construction time is short
• Small scale use is possible:
– households
– greenhouses
– Fish-farming, algal growth etc.
• Large scale is possibel too:
– District heating, heating of buildings etc.
– Drying of foods, wood, ores etc.
•
•
•
•
•
7
Environmental aspects of geothermal energy use
Air quality
All geothermal fluids contain more or less carbeonates, hydrogen-carbonates
and dissolved carbondioxide in equilibrium below the bubble point depth.
Above the bubble point depth boiling is started, and non condensable gases
(most often carbon dioxide, methane and nitrogen) are segregated, forming a
separated gas. Bertani et al (2002) investigeted 85 geothermal power plants
and determined an average 122 g/kWh carbon-dioxide emission value.
In most hydrothermal systems the oxigen concentration is very low, and in
theese systems the reduced form of sulfur, nitrogen and carbon (H2S, NH3, and
CH4), are in the gas-steam phase. In most geothermal system the ratio of the
steam-non condensable gas phase is less then 5% by mass. In binary cycle
geothermal power plant ther is not separated stem-gas phase, and gas content
of the fluid is recharged into reservoir.
8
In direct-use systems the gas-steam phase is separated, methane could be
fired in a gas-motor, ammonia and hydrogen sulfide separated, while carbondioxide is emitted into environment.
In some cases the steam-gas phase could contain volatile Hg, Rn, B, N2 and He
components. The most important air pollutatnts are: CO2, H2S, NH3, Hg, As and
H3BO3. (H2S is the most irritating).
Air pollution is higher at high-enthalpy, mostly liquid phase fluids.
Air pollution is happening mainly during the energy pruduction.
Recgarging and/or waste heat multistep use diminishes the air pollution.
9
Some air pollution examples at geothermal power plants (mg/kg) (Hg
mg/kg) Brown, Ellis
CO2 and H2S emission in Icelandic power plants (Armannsson)
10
Typical steam-gas phase compositions (g/kg)
(Barbier 1997)
Components
(g/kg)
The
Geysers
USA
Larderello
Italy
Matsukawa
Japan
Wairakei
N.Z.
Cerro
Prieto
Mexico
H2O
995.9
953.2
986.3
997.5
984.3
CO2
3.3
45.2
12.4
2.3
14.1
H2S
0.2
0.8
1.2
0.1
1.5
NH3
0.2
0.2
CH4 + H2
0.2
0.3
Others
0.2
0.3
0.1
0.1
0.1
11
Surface and subsurface water pollution
Dissolved salts: Na, K, Ca, Sr, Ba, Ra, Li, Mg, Fe, NH4+, Cl-, SO42-, HCO3-, CO32-,
F-, NO3-, HPO42-, HS-, Br-, I-, SiO2
Dissolved toxic components: Li, B, As, H2S, Hg, Cu, Pb, Cd, Fe, Zn, Mn, Al
Liquid wastes are generated during drilling and production too. Most
danerous are the hot, toxis, alkaline or acidic, high salt content fluids. Toxicity
depends on the temperature of the fluid and on the type of the reservoir
rocks.
12
Pollutants and toxic components concentrations in geothermalwaste waters
(mg/kg) mercury (mg/kg) ( Ellis & Mahon 1977, Ellis 1978, Brown, 2000)
13
Waste heat
Waste heat is generally high for geothermal plants compared to other energy
types. According to DiPippo (1991), a liquid dominated geothermal field
releases 8 times more liquid heat per year than conventional fossil fuel fired
power plants, while a vapor dominated field releases nearly 4 times as much
heat.
In case all waste liquid is reinjected into the deep reservoir this impact is zero,
otherwise hot waste liquid can rise the temperature locally so that animals and
vegetation are killed.
The impact of the disposal of hot waste liquid depends on many factors, such
as the amount and temperature of the waste stream, but also on climatic and
seasonal conditions and on the flow characteristics and temperature of a river
or lake.
14
The used thermal waters of high temperature and organic matter content
conducted upon the ground surface into the rivers or lakes are increasing the
heat and pollution load of surface waters and that of the geological
formations.
They are damaging the natural ecosystem through increasing the pollution
and temperature of the recipient. Even a 2-3-oC-increase in the temperature
of water as a result of discharging wastewater can damage the ecosystem.
Hydrobiological processes increases and dangerous changes in the biological
equilibrium can be expected. The solubility of oxygen decreases.
The plant and animal organisms that are most sensitive to temperature
variations can gradually disappear.
In many cases the thermal water utilisation and drain systems are
constructed with the insertion of a cooling pool to make possible the cooling
of water below 40 oC in such situations as well.
15
Waste heat emissions of power plant types
Thermal power (MWe) / electric power (MWe)
0
Gas
1
2
3
4
5
6
7
8
9
10
Gas (combined cycle)
1.1
Gas (single cycle)
Oil
1.6
Coal
1.7
Nuclear
2.0
Solar Thermal
Geothermal
3.0
2.3
Direct steam
Double flash
Single flash
Binary
4.4
4.8
5.3
9.0
Waste heat of different power generation technologies
Rybach 2005
16
Subsidence
oSubsidence of the ground is an irreversible process as a result of fluid
withdrawal due to geothermal exploitation. When fluid withdrawal exceeds
natural inflow, the pressure in pore spaces reduces.
oThe amount of subsidence in an area depends both on the production rate
and on physical-mechanical properties of the reservoir such as lithostatic pressure,
enthalpy of the reservoir fluid, elastic moduli of the rock and can possibly be
accompanied by (undetectable) effects of compaction of the caprock and reservoir
thermo-elastic contraction (Ciulli et al., 2005).
Change in thermal features
This is due to a decline in reservoir pressure because of mass withdrawal
during production. Pressure reduction can cause a drawdown of the
groundwater table through permeable paths in the bedrock and results in a
reduced amount of geothermal fluids reaching the surface.
17
Land use
The land that is occupied by the exploitation equipment and a large part
around this area can not be
used for other purposes either for mankind or to serve as habitat for living
species.
Might cause loss of valuable cultural sites or recreational area for example
and might result in some social effects and might have an impact on the
biodiversity of the area under exploitation.
The amount of land occupied by geothermal exploitation is much smaller
than for other renewable energy sources.
18
Land requirement for power plants
3
2
specific land requirement [10 m /MWe]
0
10
20
30
40
Solar PV
60
70
66.0
Coal
40.0
Solar Thermal
Nuclear
50
28.0
10.0
Geothermal
Flash cycle
2.7
Binary cycle
1.2
Rybach 2005
19
Noise
oPeriodic blasting noise could occur during construction of well pads, sumps
and the power plant site, which can be reduced with the help of noise shields
around drilling rigs and residential grade mufflers.
oDuring operation noise could increase above ambient levels, but these
effects would not contain any perceptible high frequency tones and would
produce a neutral, indistinguishable sound. Noise above ambient level could
have adverse impacts, especially on noise sensitive wildlife species.
Sound levels
20
Potential environmental impacts of direct use geothermal projects:
probability and severity (from Lunis 1989).
Impact
Probability of
occurring
Severity of consequences
Air pollution
L
M
Surface water pollution
M
M
Underground pollution
L
M
Land subsidence
L
L to M
High noise levels
H
L to M
Well blowouts
L
L to M
L to M
M to H
Socioeconomic problems
L
L
Solid waste disposal
M
M to H
Conflicts with cultural and
archeological features
Pollution can be chemical and/or thermal
L = low, M = medium, H = high
21
CO2 emission
(Ton/MWh)
Coal
0,1000
Oil
0,750
Natural
Gas
0,500
0,250
Geotermia
Source: EIA 1998; Bloomfield and Moore 1999
22
Typical exploitation of a geothermal field
23
Some environmental aspects of the Hungarian geothermal
energy production
Dissolved materials
Dissolved materials, such as sodium chloride (NaCl), boron (B), in some cases
traces of arsenic (As) and mercury (Hg) – whose concentrations usually
increase with temperature – is a source of pollution if discharged directly into
the environment. There may be a need for monitoring in case their
concentrations exceed permitted pollution limits.
Thermal waters cooled in the course of utilisation are usually released to public
sewers, drainage canals, sometimes at lakes or storage reservoirs or occassionall
used for irrigation. But in many cases the total dissolved salt content of
thermal waters or equivalent % of Na is exceeding the limit value below which
used waters may be disposed in public sewers without pollution fee or used
for irrigation without spoiling soil quality.
24
In some geothermal direct use systems the used warm water is collected in a
surface lake, and after cooling is partially discharged.The total dissolved solid
(TDS) content or the sodium content of this water is often above the limiting
values. cooling. These waters can be discharged only with dilution.
For discharge important characteristics are:
Na %: ratio of sodium between cations
Na 
Na% 
 100
(Ca 2  )  ( Mg 2  )  ( Na  )  ( K  )
If in the water HCO3- is dominating, max Na % is 35%.
If in the water Cl- is dominating, max Na % is 45%.
25
SAR (sodium adsorption ratio)
SAR 
Na 
Ca 2   Mg 2 
2
Na cause alkalization in soil!!
26
Total salt content in Hungarian thermal waters
Specific conductivity
Wells
Surface water
Specific conductivity measures the total dissolved solid content!
27
Salt content of some Hungarian Thermal
Water
Zalakaros
~11600 mg/l
91 %
Mezőkövesd
~4200 mg/l
39 %
Kistelek
~1500 mg/l
94%
Szentes
~2000 mg/l
97 %
Hévíz, Bogács, Eger
< 1000 mg/l
14%, 20 %, 11 %
Bükfürdő
~10000 mg/l
89 %
- TDS
- Na eq%
Na eq % = Na eq / (Na eg + K eq + Ca eq + Mg eq) * 100
MSZ 1484-3 (6. point) standard
Na eq = Na mg/l /23
K eq = K mg/l /39,1
Ca eq = Ca mg/l /20
Mg eq = Mg mg/l28/12
•Radioactive isotopes (226Ra, 228Ra, 222Rn)
Mined thermal water contain mor or less 238U and 235U isotopes and their
decay products, among other radioactive 226Ra, 228Ra, 222Rn in dissolved form
or as scale.
Radon gas bubbles out very easily from thermal water and diluted with air is
less dangerous.
Isotopes of radium, like calcium, magnesium and barium precipitate as sulfate
type scale. High energy gamma-ray of 226Ra maydanegerous and such type os
separated scale should be stored in a closed separated place. Radium could be
separated from water by adding barium-chloride.
•Organic compounds (humic acids, phenols etc.)
Environmentally dangerous aromatic and polyaromatic compounds may be
present in high concentration only at higher temperatures. In some Hungarian
thermal water there are detectable amounts of phenolic and alky-benzene
types of organic compounds. COD~20-70 mg O2/l .
29
•Boron compounds
Boron compounds are present in some Hungarian thermal waters with several
hundreds of ppm concentration. They are potential pollutants for the
environment. Boron dissolved in water is an essential element for the plants,
but above 1 ppm it is toxic. Boron compounds can be removed by adsorption,
ion exchange or memnrane separation.
•Arsenic compounds
Some Hungarian thermal waters contain considerable (~10 mg/l) amount of
arsenic compounds. The cooled water should not recharged into surface
waters without arsenic removal. Water containing arsenites and arsenates, the
former forms are more toxic. Human consumption is possible below 50 mg/l,
for watering this limit is 200 mg/l. Arzenic compounds could be removed from
thermal water by adsorption, ion exchange and membrane separation.
30
As, B content and phenol index in some Hungarian geothermal water
well
CSERKESZŐLŐ
HAJDÚSZOBOSZLÓ
SÁRVÁR
ZALAKOMÁR
CSERKESZŐLŐ
ZALAKAROS
ZALAKAROS
ZALAKAROS
BÜKKSZÉK
ZALAKAROS
BÜKKSZÉK
BÜKKSZÉK
ZALAKAROS
BÜKKSZÉK
ZALAKAROS
BÜKKSZÉK
NYÍREGYHÁZA
SÁRVÁR
ZALAKAROS
ZALAKAROS
NYÍREGYHÁZA
ZALAKAROS
B
mg/l
203519
185017
128278
106076
88487
88310
83874
76054
74130
74007
72477
70923
69073
67839
67839
66606
62905
61672
61672
61672
60439
60300
well
No
As
mg/l
MEZŐCSÁT
46
930
MEZŐKÖVESD
48
620
MEZŐKÖVESD
48
620
CSERKESZŐLŐ
1
584
MEZŐKÖVESD
48
570
BÉKÉS
27
500
POROSZLÓ
34
480
GÁLOSFA
4
400
BÉKÉS
46
360
BÉKÉS
29
339.64
NAGYSZÉNÁS
13
300
ABÁDSZALÓK
40
290
POROSZLÓ
34
280
NAGYSZÉNÁS
13
270
FÜZESGYARMAT
34
230
KÖRÖSÚJFALU
4
201
GÁLOSFA
4
200
KISVÁRDA
154
200
CSORNA
47
200
BÉKÉSCSABA
1019
200
FÜZESGYARMAT
41
200
well
No
SZEGED
SZEGED
BÉKÉSCSABA
SZEGED
GYULA
SZEGED
SZARVAS
SZARVAS
SZÉKKUTAS
SZARVAS
DESZK
SZARVAS
DOMASZÉK
VÉGEGYHÁZA
MEZŐTÚR
SZEGED
TÚRKEVE
ÖCSÖD
TÓTKOMLÓS
OROSHÁZA
HÓDMEZŐVÁSÁRHELY
MAKÓ
MAKÓ
BÉKÉSCSABA
SZARVAS
BÉKÉSCSABA
KISKUNMAJSA
CSERKESZŐLŐ
SZENTES
SZARVAS
SZEGED
376
650
953
474
453
602
61
87
271
80
40
110
25
19
140
476
26
46
145
481
1077
230
189
282
81
282
49
1
658
88
453
fenol ind.
mg/l
100
13.8
8.59
8.25
6.872
5.895
5.87
5.59
5.55
5.3
4.527
4.36
3.691
3.17
3.1
3.092
3.02
2.98
2.92
2.917
2.9
2.6
2.1
1.94
1.9
1.8
1.44
1.4
1.34
1.25
1.022
K, Na content and water hardness (mg/l) in some Hungarian geothermal water
well
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
SÁRVÁR
GÖDÖLLŐ
SÁRVÁR
GÖDÖLLŐ
GÖDÖLLŐ
No
23
36
36
36
23
23
23
36
36
36
36
36
74
36
74
74
K+
BALATONSZABADI
CSERKESZŐLŐ
KAPUVÁR
CSERKESZŐLŐ
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
49
1
84
1
1
1
1
1
1
1
8
8
9
1
1
150
SÁRRÉTUDVARI
BÜKKSZÉK
BÜKKSZÉK
BÜKKSZÉK
KAPUVÁR
19
9
9
9
61
1100
1280
680
570
900
770
1020
146
127
99.8
93.2
96.72
100
178.4
72.6
95
120
Na+
26544.5
17500
17000
16916
16600
16292.7
16211.5
16128.6
16000
15500
14800
14800
14000
13684.5
13279.7
13067.4
10600
10376
9800
8884.9
7850.3
7797
7784.3
7452
7254.89
6800.91
6796
6796
6750
6607.4
6533.4
6323.62
6200
6140
6100
6000
well
BÜK
BÜK
BÜK
BÜK
BÜK
SZOMBATHELY
BALATONSZABADI
SZOMBATHELY
BÜK
SÁRRÉTUDVARI
BÜK
PÉCSVÁRAD
BÜK
GÖDÖLLŐ
GÖDÖLLŐ
GÖDÖLLŐ
KISKŐRÖS
KISKŐRÖS
HEVES
KAPOSSZEKCSŐ
BÜK
DÉVAVÁNYA
HEVES
BUDAPEST-XIV.KER.
VAJTA
TÁPIÓGYÖRGYE
ZALACSÁNY
SÁRVÁR
KEHIDAKUSTÁNY
BÜK
MEZŐKÖVESD
BÜK
ZALACSÁNY
SÁRVÁR
SZEGED
SÁRVÁR
SÁRVÁR
hardness
8721
7226
7168
5152
5152
4750
4652
4450
4379
3448.52
3048
2960
2280
2260.05
2250
2200
1912
1880
1520
1460
1331
1320
1180
1092
1072
920
900
858
844
841.39
827.39
820
820
817.13
812
803.34
802.13
32
28/2004. (XII. 25.) KvVM Governmental Decree
Emission limits
Parameter
Unit
Energetical
use
Balneological
use
Thermal bath
Chemical Oxigen
Demand (COD)
mg/l
-
150
-
TDS
mg/l
3000
5000
2000
%
45
95
45
Ammonia-ammoniumnitrogen
mg/l
-
10
-
Sulfids
mg/l
-
2
-
Phenolindex
mg/l
1.0
-
-
Total barium
mg/l
-
0.5
-
oC
30
30
30
Sodium-equivalent
Heat discharge
33
34
Variations of the wellhead pressures in Szeged ,Székelysor well
(By Dr Török, J.)
35
Thank you!
36