Csilla Tonkó , GyörgyPátzay BME KKFT&MTET 6. May. 2011 RENEXPO 2011

1. ENVIRONMENTAL ASPECTS OF GEOTHERMAL ENERGY USE IN HUNGARY Csilla Tonkó, GyörgyPátzay BME KKFT&MTET 6. May. 2011 RENEXPO 2011

2. Geothermalenergy • Geothermalenergy is one of thecleanest, partiallyrenewableenergy. • Conventionalgeothermalenergy (100-2500m depth) can be useddirectlyforheating, dryingstc. orindirectlyforelectricenergyproduction. • Geothermalfluidsaremulticomponent, multiphasefluidsorsteam, containingdissolvedsolid, gas, organicmaterials and suspendedsolidparticles. Thesecomponentsconcentrationsvaryin a broadscale. • Concentration of thedissolvedcomponentsareusuallyincreasingwithtemperature. Somecomponents (toxic etc.) should be removedbeforeoraftertheenergeticuse. • Potentiallythecomponentswithhighrisk (Hg, B, As, and Cl) could be separated, and theused fluid should be rechargedintothereservoir.

3. Somegeothermalwellsarepotentiallysuitableforelectricenergyproduction (ORC) in Hungary

4. 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.

5. 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.

6. Otherpossibilities: • Heatpumpheatingusinggeothermalheat. • Example: Szeged city . The building of theEnvironmentalauthority is heated. 15 drilled 120 m deepheatexchangerused. • DistrictheatingwithgeothermalwellsusingrechargingwellsintoUpper-PannoniansandstoneinHódmezővásárhely. Since 1998 thesystem is in service. • The GeoGas Energia-hasznosító és Szolgáltató Co. developed a project tousetheseparatedmethanecontent of 32 geothermalwellsingasenginestoproduceelectricity. The mathanecontent of thesewellsarebetween 65-95%. The project containsfutureuse of 27 gasengines (7 with 201 kWe, 10 with 150 kWe and 10 with 105 kWecapacity.)

7. Geothermalenergydirectuse has advantages: • Low- and medium-enthalpyfluidscould be used(<150oC) • Theesefluidsarethe most of thefluids(80 countries) • Indirectuse no convection-highefficiency • Conventional drilling technologycan be used • Conventional, nottooexpensivedevicesareneeded (fitted onthetemperature and chemistry of thefluids) • Constructiontime is short • Smallscaleuse is possible: • households • greenhouses • Fish-farming, algalgrowth etc. • Largescale is possibeltoo: • Districtheating, heating of buildings etc. • Drying of foods, wood, ores etc.

8. Environmentalaspects of geothermalenergyuse • Air quality • Allgeothermalfluidscontain more or less carbeonates, hydrogen-carbonates and dissolvedcarbondioxideinequilibriumbelowthebubblepointdepth. Abovethebubblepointdepthboiling is started, and non condensablegases (most oftencarbondioxide, methane and nitrogen) aresegregated, forming a separatedgas. Bertani et al (2002) investigeted 85 geothermalpowerplants and determined an average122 g/kWhcarbon-dioxideemissionvalue. • In most hydrothermalsystemstheoxigenconcentration is verylow, and intheesesystemsthereducedform of sulfur, nitrogen and carbon(H2S, NH3, and CH4), areinthegas-steamphase. In most geothermalsystemthe ratio of thesteam-noncondensablegasphase is less then 5% bymass. Inbinarycyclegeothermalpowerplantther is notseparatedstem-gasphase, and gascontent of the fluid is rechargedintoreservoir.

9. Indirect-usesystemsthegas-steamphase is separated, methanecould be firedin a gas-motor, ammonia and hydrogensulfideseparated, whilecarbon-dioxide is emittedintoenvironment. • Insomecasesthesteam-gasphasecouldcontainvolatileHg, Rn, B, N2 and Hecomponents. The most important air pollutatntsare: CO2, H2S, NH3, Hg, As and H3BO3. (H2S is the most irritating). • Air pollution is higherathigh-enthalpy, mostlyliquidphasefluids. • Air pollution is happening mainlyduringtheenergypruduction. • Recgarging and/orwasteheatmultistepusediminishesthe air pollution.

10. Some air pollutionexamplesatgeothermalpowerplants (mg/kg) (Hgmg/kg) Brown, Ellis CO2and H2S emissioninIcelandicpowerplants(Armannsson)

11. 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 0.1 CH4 + H2 0.2 0.3 Others 0.2 0.3 0.1 0.1 Typicalsteam-gasphasecompositions (g/kg)(Barbier 1997)

12. Surface and subsurfacewaterpollution • Dissolvedsalts: Na, K, Ca, Sr, Ba, Ra, Li, Mg, Fe, NH4+, Cl-, SO42-, HCO3-, CO32-, F-, NO3-, HPO42-, HS-, Br-, I-, SiO2 • Dissolvedtoxiccomponents:Li, B, As, H2S, Hg, Cu, Pb, Cd, Fe, Zn, Mn, Al • Liquidwastesaregeneratedduring drilling and productiontoo. Most danerousarethe hot, toxis, alkalineoracidic, highsaltcontentfluids. Toxicitydependsonthetemperature of the fluid and onthetype of thereservoirrocks.

13. Pollutants and toxiccomponentsconcentrationsingeothermalwastewaters(mg/kg) mercury(mg/kg) ( Ellis & Mahon 1977, Ellis 1978, Brown, 2000)

14. Wasteheat • Wasteheat is generallyhighforgeothermalplantscomparedtootherenergytypes. AccordingtoDiPippo (1991), a liquiddominatedgeothermalfieldreleases 8 times more liquidheat per yearthanconventionalfossilfuelfiredpowerplants, while a vapordominatedfieldreleasesnearly 4 timesasmuchheat. • Incaseallwasteliquid is reinjectedintothedeepreservoirthisimpactiszero, otherwise hot wasteliquidcanrisethetemperaturelocallysothatanimals and vegetationarekilled. • The impact of thedisposalof hot wasteliquiddependsonmanyfactors, suchastheamount and temperature of thewastestream, butalsoonclimatic and seasonalconditionsandonthe flow characteristics and temperature of a riverorlake.

15. The usedthermalwaters of hightemperature and organicmattercontentconducteduponthegroundsurfaceintotheriversorlakesareincreasingtheheatandpollutionload of surfacewaters and that of thegeologicalformations. • Theyaredamagingthenaturalecosystemthroughincreasingthepollution and temperature of therecipient. Even a 2-3-oC-increase inthetemperature of wateras a result of dischargingwastewatercandamagetheecosystem. Hydrobiologicalprocessesincreases and dangerouschangesinthebiologicalequilibriumcan be expected. The solubility of oxygendecreases. • The plant and animalorganismsthatare most sensitivetotemperaturevariationscangraduallydisappear. • Inmanycasesthethermalwaterutilisation and drainsystemsareconstructedwiththeinsertion of a coolingpooltomakepossiblethecooling of waterbelow 40oCinsuchsituationsaswell.

16. Waste heat of different power generation technologies Rybach 2005

17. Subsidence • Subsidence of theground is an irreversibleprocessas a result of fluid withdrawalduetogeothermalexploitation. When fluid withdrawalexceedsnaturalinflow, thepressureinporespacesreduces. • The amount of subsidencein an areadependsbothontheproductionrate • and onphysical-mechanicalproperties of thereservoirsuchaslithostaticpressure, enthalpyofthereservoir fluid, elastic moduli of the rock and canpossibly be accompaniedby (undetectable) effects of compactionofthecaprock and reservoirthermo-elasticcontraction (Ciulli et al., 2005). • Changeinthermalfeatures • This is dueto a declineinreservoirpressurebecause of masswithdrawalduringproduction. Pressurereductioncancause a drawdown of thegroundwatertablethroughpermeablepathsinthebedrock and resultsin a reducedamount of geothermalfluidsreachingthesurface.

18. Landuse • The landthat is occupiedbytheexploitationequipment and a large part aroundthisareacannot be • usedforotherpurposeseitherformankindortoserveashabitatforliving species. • Mightcauseloss of valuableculturalsitesorrecreationalareaforexample and mightresultinsomesocialeffectsandmighthave an impactonthebiodiversity of theareaunderexploitation. • The amount of landoccupiedbygeothermalexploitation is muchsmallerthanforotherrenewableenergysources.

19. Rybach 2005

20. Noise • Periodicblastingnoisecouldoccurduringconstruction of wellpads, sumps and thepowerplant site, whichcan be reducedwiththehelp of noiseshieldsaround drilling rigs and residentialgrademufflers. • Duringoperationnoisecouldincreaseaboveambientlevels, buttheseeffectswouldnotcontainanyperceptiblehighfrequencytones and wouldproduce a neutral, indistinguishablesound. Noiseaboveambientlevelcouldhaveadverseimpacts, especiallyonnoisesensitivewildlife species. Soundlevels

21. Table 1: 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 Conflicts with cultural and archeological features L to M M to H Socioeconomic problems L L Solid waste disposal M M to H Potential environmental impacts of direct use geothermal projects: probability and severity (from Lunis 1989). Pollution can be chemical and/or thermal L = low, M = medium, H = high

22. Coal Oil CO2 emission (Ton/MWh) Natural Gas Geotermia 0,1000 Source: EIA 1998; Bloomfield and Moore 1999 0,750 0,500 0,250

23. Typical exploitation of a geothermal field

24. Someenvironmentalaspects of theHungariangeothermalenergyproduction Dissolvedmaterials Dissolvedmaterials, suchassodiumchloride(NaCl), boron (B), insomecasestraces of arsenic(As) and mercury(Hg) – whoseconcentrationsusuallyincreasewithtemperature – is a source of pollutionifdischargeddirectlyintotheenvironment. Theremay be a needfor monitoring incasetheirconcentrationsexceedpermittedpollutionlimits. Thermalwaterscooledinthecourse of utilisationareusuallyreleasedtopublicsewers, drainagecanals, sometimesatlakesorstoragereservoirsoroccassionallusedforirrigation. Butinmanycasesthetotaldissolvedsaltcontent of thermalwatersorequivalent % of Na is exceedingthe limit valuebelowwhichusedwatersmay be disposedinpublicsewerswithoutpollutionfeeorusedforirrigationwithoutspoilingsoilquality.

25. Insomegeothermaldirectusesystemstheusedwarmwater is collectedin a surfacelake, and aftercooling is partiallydischarged.Thetotaldissolvedsolid (TDS) contentorthesodiumcontent of thiswater is oftenabovethe limiting values. cooling. Thesewaterscan be dischargedonlywithdilution. Na %: ratio of sodiumbetweencations Ifinthewater HCO3- is dominating, maxNa % is 35%. Ifinthewater Cl- is dominating, max Na % is 45%. Fordischargeimportantcharacteristicsare:

26. SAR (sodiumadsorption ratio) • Na causealkalizationinsoil!!

27. Total saltcontentinHungarianthermalwaters Specificconductivity Surfacewater Wells Specificconductivitymeasuresthetotaldissolvedsolidcontent!

28. Salt content of someHungarianThermalWater Kistelek ~1500 mg/l 94% Bükfürdő ~10000 mg/l 89 % • TDS • Na eq% Hévíz, Bogács, Eger < 1000 mg/l 14%, 20 %, 11 % Na eq % = Naeq / (Naeg + K eq + Caeq + Mg eq) * 100 MSZ 1484-3 (6. point) standard Na eq = Na mg/l /23 Caeq = Ca mg/l /20 K eq = K mg/l /39,1 Mg eq = Mgmg/l /12

29. Radioactiveisotopes(226Ra, 228Ra, 222Rn) • Minedthermalwatercontainmoror less 238U and 235U isotopes and theirdecayproducts, amongotherradioactive226Ra, 228Ra, 222Rn indissolvedformorasscale. • Radon gasbubbles out veryeasilyfromthermalwater and dilutedwith air is less dangerous. • Isotopes of radium, likecalcium, magnesium and bariumprecipitateassulfatetypescale. Highenergygamma-ray of 226Ra maydanegerous and suchtypeosseparatedscaleshould be storedin a closedseparatedplace. Radiumcould be separatedfromwaterbyaddingbarium-chloride. • Organiccompounds(humicacids, phenols etc.) • Environmentallydangerousaromatic and polyaromaticcompoundsmay be presentinhighconcentrationonlyathighertemperatures. InsomeHungarianthermalwatertherearedetectableamounts of phenolic and alky-benzenetypes of organiccompounds. COD~20-70 mg O2/l .

30. Boron compounds • Boron compoundsarepresentinsomeHungarianthermalwaterswithseveralhundreds of ppmconcentration. Theyarepotentialpollutantsfortheenvironment. Boron dissolvedinwater is an essentialelementfortheplants, butabove 1 ppmit is toxic. Boron compoundscan be removedbyadsorption, ion exchangeormemnraneseparation. • Arseniccompounds • SomeHungarianthermalwaterscontainconsiderable (~10 mg/l) amount of arseniccompounds. The cooledwatershouldnotrechargedintosurfacewaterswithoutarsenicremoval. Watercontainingarsenites and arsenates, theformerformsare more toxic.Human consumption is possiblebelow50 mg/l, forwateringthis limit is 200 mg/l.Arzeniccompoundscould be removedfromthermalwaterbyadsorption, ion exchange and membraneseparation.

31. As, B content and phenol index insomeHungariangeothermalwater

32. K, Na content and waterhardness (mg/l) insomeHungariangeothermalwater

33. 28/2004. (XII. 25.) KvVM Governmental Decree Emission limits

35. Variations of the wellhead pressures in Szeged ,Székelysor well (By Dr Török, J.)

36. Thankyou!