Geotermalni izvori
U Hrvatskoj postoji tradicija iskorištavanja geotermalne energije iz prirodnih izvora u medicinske svrhe i za kupanje. Brojne toplice koriste upravo geotermalnu energiju (Varaždinske Toplice, Daruvarske Toplice, Stubičke Toplice, Lipik, Topusko itd.). Proizvodnja geotermalne vode za navedene toplice prije se vršila kroz prirodne izvore, dok se danas uz prirodni protok koristi geotermalna voda iz plitkih bušotina. Ukupno postoji 28 nalazišta, od kojih je 18 u upotrebi.
INA-Naftaplin je 1970-ih godina započela s istraživanjem rezervi nafte i plina na poljima u kontinentalnom dijelu Hrvatske. Istražne bušotine pokazale su postojanje izvora tople vode. Najviše istražena ležišta, a ujedno i ležišta s najvišom temperaturom geotermalnog fluida su ležište u blizini Koprivnice (Kutnjak-Lunjkovec) i Bjelovara (velika Ciglena).
40 godina kasnije nezamisliv i neoprostiv zastoj.
Zašto?
1998. godine Energetski institut “Hrvoje Požar” je pripremio program korištenja geotermalne energije u Hrvatskoj, koji pokazuje da Hrvatska ima nekoliko srednjetemperaturih geotermalnih izvora s relativno niskim temperaturama geotermalne vode u rasponu od 100 do 140°C, pomoću kojih je moguća proizvodnja električne energije, npr. Lunjkovec (125°C), Ferdinandovac (125°C), Babina Greda (125°C) i Rečica (120°C). No, konkretne inicijative za gradnju geotermalnih elektrana pokrenute su tek posljednjih godina. Za proizvodnju električne energije iz srednjetemperaturnih geotermalnih izvora dolaze u obzir elektrane s binarnim ciklusom, bilo s organskim Rankineovim ciklusom (ORC) ili Kalina ciklusom.
U literaturi se Kalina ciklus navodi kao termodinamički povoljniji ciklus od ORC, tj. koji postiže veću termodinamičku iskoristivost i daje više snage. S druge strane, spoznaje autora objavljene u prethodnim radovima, a predstavljene i na 3. međunarodnom forumu o obnovljivim izvorima energije ovdje u Dubrovniku, dobivene na temelju proračuna za srednjetemperaturni geotermalni izvor u Hrvatskoj (Velika Ciglena) s relativno visokom temperaturom geotermalne vode (175°C) pokazuju suprotno. ORC je termodinamički bolji od Kalina ciklusa. To se objašnjava relativno visokom temperaturom geotermalne vode kao i relativno visokom prosječnom godišnjom temperaturom zraka za hlađenje u kondenzatoru (15°C), koja ima nepovoljniji utjecaj kod Kalina ciklusa nego kod ORC-a. U ovom će se radu usporedba ORC i Kalina ciklusa provesti za srednjetemperaturno geotermalno polje s relativno niskom temperaturom geotermalne vode (125°C) i ponovo uz relativno visoku prosječnu godišnju temperaturu zraka za hlađenje u kondenzatoru (15°C): konkretno za geotermalno polje Lunjkovec. Usporedba ORC i Kalina ciklusa će se provesti na temelju rezultata energetske i eksergetske analize.
Konačni cilj usporedbe je predložiti povoljnije binarno postrojenje, bilo s ORC ili Kalina ciklusom, za srednjetemperaturne geotermalne izvore u Hrvatskoj s relativno niskim temperaturama geotermalne vode.
14 godina kasnije nezamisliv i neoprostiv zastoj.
Zašto?
Geotermalna energija je toplinska energija koja se stvara u Zemljinoj kori polaganim raspadanjem radioaktivnih elemenata, kemijskim reakcijama, kristalizacijom i skrućivanjem rastopljenih materijala ili trenjem pri kretanju tektonskih masa. Količina takve energije je tako velika da se može smatrati skoro neiscrpnom. Iskorištavanje geotermalne energije podrazumijeva iskorištavanje energije nagomilane u unutrašnjosti Zemlje u obliku vruće vode i pare ili u suhim stijenama. Pri tome je bitna razlika temperatura između površine i unutrašnjosti Zemlje. Temperaturni gradijent, odnosno povećanje temperature po kilometru dubine, najveći je neposredno uz površinu, a s povećanjem udaljenosti od površine postaje sve manji. Za praktično iskorištavanje geotermalne energije potrebno je iskoristiti prirodno strujanje vode ili stvoriti uvjete za takvo strujanje. Osnovno načelo je da se voda dovodi s površine Zemlje u dublje slojeve, u njima se ugrije preuzimajući toplinu nagomilanu u Zemljinoj unutrašnjosti i tako ugrijana ponovno pojavljuje na površini.
|
Hrvatski geološki institut
Croatian Geological Survey
U istraživanjima se koriste najsuvremenije metodologije kao i informacijske i računalne tehnologije. U institutu je aktivno 66 znanstvenika i istraživača i 12 znanstvenih novaka na realizaciji Programa temeljne djelatnosti (Geološke karte), pitanjima zaštite okoliša, istraživanju podzemnih voda, inženjerskogeoloških karakteristika terena te istraživanju mineralnih sirovina.
Hrvatski geološki institut surađuje s mnogim srodnim institucijama, organizacijama i fakultetima u zemlji, a kao takav prepoznat je i u međunarodnoj akademskoj zajednici o čemu svjedoče mnogi međunarodni istraživački projekti koji se izvode u Institutu.
Energetski potencijal u Republici Hrvatskoj
Geotermalni gradijent
G=0,018 °C/m q=29 mW/m2 |
G=0,049 °C/m
q=76 mW/m2
Geotermalni potencijal
do 50°C | do 25°C | |
Iz već izrađenih bušotina:
|
203,47 | 319,21 |
Uz potpunu razradu ležišta:
|
839,14 | 1169,97 |
Srednjetemperaturni geotermalni potencijali
Područje
|
Bjelovar
|
Bjelovar
|
Ludbreg
|
Đurđevac
|
Karlovac
|
Županja
|
Lokacija (ležište)
|
Velika
Ciglena
|
Velika
Ciglena
|
Lunjkovec
|
Ferdinan-
dovac
|
Rečica
|
Babina
Greda
|
Kategorija rezervi
|
Dokazane
|
Vjerojatne
|
Vjerojatne
|
Vjerojatne
|
Vjerojatne
|
Vjerojatne
|
Dokazane
|
||||||
Dubina bušotina, m
|
2800
|
2800
|
2500
|
2500
|
2500
|
2500
|
Način pridobivanja vode
|
samoizljev
|
samoizljev
|
samoizljev
|
samoizljev
|
crpka
|
samoizljev
|
Izdašnost elementa razrade, m3/s
|
0,11566
|
0,347
|
0,156
|
0,1
|
0,1
|
0,2
|
Temperatura vode, °C
|
170
|
170
|
125
|
125
|
120
|
125
|
Broj bušotina na elementu; (proizvodne + utisne)
|
2 (1+1)
|
5 (3+2)
|
3 (2+1)
|
3 (2+1)
|
3 (2+1)
|
2 (1+1)
|
Mogući broj elemenata razrade
|
1
|
1
|
10
|
1
|
1
|
1
|
Broj izrađenih/aktivnih bušotina
|
2/0
|
2/0
|
3/0
|
1/0
|
1/0
|
1/0
|
do 50°C | do 25°C | |
Iz već izrađenih bušotina:
|
168,74 | 218,07 |
Uz potpunu razradu ležišta:
|
755,79 | 986,64 |
Iz već izrađenih bušotina:
|
10,95 MWe |
Uz potpunu razradu ležišta:
|
47,88 MWe |
Niskotemperaturni geotermalni potencijali
do 50°C | do 25°C | |
Iz već izrađenih bušotina:
|
25,81
|
47,67
|
Uz potpunu razradu ležišta:
|
74,42
|
129,86
|
Područje |
Zagreb
|
Valpovo
|
Osijek
|
Samobor
|
|||
Lokacija (ležište) |
Mladost
|
Sveuč.bolnica
|
Bizovac -TG
|
Bizovac -PP
|
Madrinci
|
Ernesti -novo
|
SvetaNedelja
|
Kategorija rezervi |
Dokazane
|
Dokazane
|
Dokazane
|
Dokazane
|
Vjerojatne
|
Vjerojatne
|
Vjerojatne
|
Vjerojatne
|
|||||||
Dubina bušotina, m |
1300
|
1300
|
1800
|
1800
|
1900
|
1700
|
1400
|
Način pridobivanja vode |
samoizljev
|
samoizljev
|
samoizljev
|
crpka
|
samoizljev
|
crpka
|
samoizljev
|
Izdašnost elementa razrade, m3/s |
0,05
|
0,055
|
0,003
|
0,046
|
0,01
|
0,046
|
0,09
|
Temperatura vode, °C |
80
|
80
|
96
|
90
|
96
|
80
|
68
|
Broj bušotina na elementu; (proizvodne + utisne) |
3 (1+2)
|
4 (2+2)
|
2 (1+1)
|
3 (2+1)
|
2 (1+1)
|
3 (2+1)
|
3 (2+1)
|
Mogući broj elemenata razrade |
1
|
1
|
1
|
6
|
1
|
1
|
1
|
Broj izrađenih/aktivnih bušotina |
3/3
|
4/1
|
2/2
|
1/1
|
1/0
|
1/0
|
1/0
|
Geotermalni izvori temperature manje od 65°C
do 50°C | do 25°C | |
Iz već izrađenih bušotina:
|
8,92
|
53,47
|
Uz potpunu razradu ležišta:
|
8,92
|
53,47
|
Hrvatski Centar Obnovljivih Izvora Energije (HCOIE)
Geothermal World Report
The Geothermal Report contains a global assessment of geothermal energy developments and deployments. 2010 appeared to be a weak year for geothermal with few projects commissioned and only in existing markets. However, this is not indicative of the state of the sector as a whole. As more money was invested in geothermal last year than the previous year. Several projects are now in the advanced stages of development, e.g. in the US alone there is 722 MW of project in phase 3 and 4, and support for the sector is strong. Specifically, Japan and Indonesia are relaxing rules on developing geothermal projects on protected land, which should open up more sites for development. Over the next five years high growth markets for the sector are expected to continue to be the top six main markets, Kenya, Iceland, Mexico and South America. For the latter, developers have already been awarded concessions to explore new sites in Argentina, Colombia, Chile and Peru. In the middle of 2010 the Chilean government announced plans to invest up to USD 200 million in geothermal projects and will grant over 170 geothermal concessions over the next two years, which should result in the country installing its first generation plant in the mid-term. Kenya and Mexico and the other six major markets are likely to commission projects in the advanced stages of development.
Scope
Over the next five years high growth markets for the sector are expected to continue to be the top six main markets, Kenya, Iceland, Mexico and South America. For the latter, developers have already been awarded concessions to explore new sites in Argentina, Colombia, Chile and Peru. In the middle of 2010 the Chilean government announced plans to invest up to USD 200 million in geothermal projects and will grant over 170 geothermal concessions over the next two years, which should result in the country installing its first generation plant in the mid-term. Kenya and Mexico and the other six major markets are likely to commission projects in the advanced stages of development. As part of a strategy to raise revenue Iceland is considering exporting electricity to other countries. A feasibility study is being undertaken to build a sub-sea electric cable linking Iceland to Europe to sell electricity generated from geothermal projects to Britain, Norway, Holland and Germany. Another potential growth market is Japan. The country’s geothermal power plants were largely unaffected by the recent earthquake and tsunami unlike the Fukushima nuclear power plant. As both provide base load electricity and Japan has a good geothermal re-source. Australia is also developing geothermal projects, and has several EGS and Hot Sedimentary Aquifer (HSA) projects in the pipeline. Cost is still a major barrier to the development of projects and access to finance for the exploratory stages is still a challenge.
100% RENEWABLE
Geothermal power is based on heat energy stored underneath the ground. This intense heat is trapped in enormous quantities inside water reservoirs in the earth’s crust. In fact, it is considered essentially limitless.
The superheated aquifers tapped for geothermal production are continually replenished by geologic forces originating in the core of the planet. These inexhaustible natural processes make geothermal energy an eminently renewable resource.
CLEAN-BURNING AND LOW-EMISSION
Geothermal energy is considered clean because it can be extracted and converted without burning any fossil fuels. The ‘emissions’ from a geothermal plant are mainly benign water vapors.
For evidence, we can look to Iceland whose capital Reykjavik—where 95 percent of buildings are geothermally heated—is considered one of the world’s cleanest cities.
HIGH ENERGY POTENTIAL
Oil and other ‘fossil’ fuels are just that—finite fossils that took a long time to form millions of years ago. As a result, there is only so much valuable oil we can extract from identified reserves. At some point, it could simply become cost-ineffective to drill for what’s left of the world’s petroleum—not to mention prohibitively destructive of the global climate.
Geothermal resources have astonishing energy potential by comparison, estimated at 2 terawatts globally—about 15,000 times more than estimated worldwide oil reserves.
SCALABLE PRODUCTION
Some level of geothermal energy is available in most places. There is potential for geothermal development throughout the United States, and the process is highly scalable.
Geothermal lends itself to large and commercial-scale plant operations as well as local and residential applications in the form of ground pump heating and cooling systems. Smaller operations are cheaper and can be dug at shallower levels, while large geothermal power plants can efficiently convert huge amounts of heat into electricity to feed the grid.
BASE LOAD STABILITY
Unlike renewables such as solar and wind power, geothermal energy maintains an ideal stability night and day, regardless of lighting and wind conditions. That makes it eligible to supply base load electricity to the grid.
The base load forms the primary bulk of demand for a grid’s electricity. A reliable and constant supply of power is required to meet this demand. Geothermal’s inherent stability also carries over to the price of electricity, which would see less cost fluctuation.
LIGHT ON CARBON
A geothermal system is an excellent way to substantially reduce a building’s carbon footprint. Zoe Reich, an environmental specialist with engineering firm Edwards & Zuck, says a correctly installed geothermal pump system can shave a building’s utility costs by up to 60 percent.
While geothermal energy is not entirely carbon-free, it releases a fraction as much carbon dioxide into the atmosphere as fossil fuels. Additionally, power is generated on-site at geothermal plants, saving the costly energy associated with transporting and processing pricey fuels.
LOW-MAINTENANCE VERSATILITY
Geothermal energy can replace both heating and cooling systems in buildings—and do both jobs more efficiently than conventional air-cooled systems. Why? Subsurface temperatures remain constant year-round.
Moreover, the elegant operational simplicity of a typical system and the absence of carbon fouling due to combustion mean geothermal systems are easy to maintain.
SMART LAND USE
Geothermal energy has the smallest land footprint of any major power source. It doesn’t require much additional real estate—a boon in dense urban zones.
Additionally, underground geothermal systems aren’t exposed to the elements. This is important during extreme weather as it protects crucial energy supplies from natural disasters that threaten aboveground units.
GREEN ECONOMY
The uncapped energy potential of hydrothermal reservoirs means there will never be anything like ‘peak geothermal.’ This has serious implications for job creation and the strength of the green economy.
It takes a lot of workers to build and run geothermal power plants. Each phase of development represents valuable jobs for electricians, pipefitters, engineers, recruits from top geology programs, and more.