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Geothermische energie

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Geothermal project heats up
A geothermal exploration company says an on-shore drill, bigger than any other in Australia, will arrive in Brisbane at the end of the month. The $32 million rig will be used to drill three kilometres underground, searching for hot rocks that can be used to generate power.
They are searching a site in the Cooper Basin in South Australia, close to the Queensland border.

The CEO of Geodynamics, Adrian Williams, says the aim is to supply power to the national grid by 2010.

"There's huge momentum that has built up over the last couple of months," he said.

"It started with our announcement to buy a new rig and that rig has now left the United States and at the same time I think we've seen a huge lift in public discussion and political discussion to do with climate change, so those two things together are giving us some real momentum."

Last week the Federal Government began surveying areas in central and south-west Queensland for other potential geothermal sites.

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KenGen Signs Deal for Construction of 35MW Geothermal Plant
Thomas Pearmain
The Kenya Electricity Generating Co. (KenGen) has signed an engineering, procurement, and construction (EPC) contract with Mitsubishi Corp. that will boost the country's geothermal production by 35MW. According to the East African Standard, construction will begin next month and be completed by 2009, with the Olkaria II plant being expanded from 130MW to 165MW. Funding for the project comes from a portion of the 3.6-billion-Kenya-shillings (US$55-million) loan from the French Development Agency (AFD) made earlier this year, while the European Investment Bank (EIB) promised US$40.8 million and the International Development Agency has given US$22 million; the projects total cost is expected to be US$87.5 million.Significance: The current geothermal capacity in Kenya is comprised of KenGen Olkaria I (with 45MW), Olkaria II (70MW), Orpower (13MW), and Oserian Development Co. (2MW).
Earlier this year, KenGen announced it plans to create a new entity, the Kenya Geo-Thermal Development Co., as potential exists for up to 2,000MW of geothermal energy in the Rift Valley. Last year, KenGen signed a 1.6-billion-Kenya-shillings deal with the Great Wall Drilling Co., a subsidiary of the state-owned China National Petroleum Corp., to drill geothermal wells in the Rift Valley. The Kenyan government believes geothermal power generation is the cheapest option for power generation for the next two decades. As a clean energy, the geothermal expansion project has qualified for carbon credits of about 800 million Kenya shillings under the World Bank-sponsored Clean Development Mechanism programme.

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Pertamina unit in geothermal JV
Laurel Teo In Jakarta
It ties up with Icelandic firm; US, German firms also keen to build wind powered generators AN ICELANDIC company has teamed up with a unit of state oil and gas firm Pertamina to speed up the development of Indonesia's vast and mostly untapped geothermal resources.
Reykjavik Energy and PT Pertamina Geothermal Energy will focus first on studying and exploring potential sites - an initial phase that government officials hope will begin by next year.

Sugiharto Harsoprayitno, a director with the Energy and Mineral Resources department, said: 'They will start by looking at which area has potential for development.'

Speaking to local media, he stressed that it was premature at this stage to speak of the size of any investment amounts.

The two companies signed an agreement in Iceland last week, during the Indonesia-Iceland Geothermal Forum held in the capital city, Reykjavik.

As a follow-up, the Indonesian embassy in Oslo, Norway, will organise a visit for Iceland's geothermal businessmen to Indonesia at the end of next month.

Meanwhile, Suryadarma, operations director of Pertamina Geothermal Energy, said his company would begin preliminary studies into areas with bigger potential, such as Sumatra, Java and Sulawesi islands.

He added that others interested in geothermal tie-ups with Indonesia included the Philippines' PNOC and Enel Corp of Italy.

The partnership with Iceland is part of Indonesia's efforts to speed up the growth of its geothermal sector.

Although the country is believed to have 40 per cent of the world's geothermal resources, capable of yielding over 27,700 megawatts (MW) of electricity, only about 3 to 4 per cent of the resources are being tapped at the moment.

By 2010, however, the government hopes to boost geothermal-generated electricity to 2,000 MW, up from the present level of about 900 MW. And by 2025, the geothermal sector is supposed to produce 9,500 MW. These are targets set in the government's energy plan.

Iceland, on the other hand, has plenty of experience in this sector. Geothermal power produces about 26 per cent of the North Atlantic island country's electricity, and supplies heating and hot water for 87 per cent of its homes.

Reykjavík Energy, a city-owned utilities firm, operates the world's largest and most sophisticated geothermal district-heating system.

Besides geothermal energy, Indonesia plans to harness wind energy. Private companies from the United States and Germany have already expressed their interests in building wind-powered generators.

J Purwono, who heads the government's electricity and energy usage unit, told a parliamentary commission on Monday that the American and German companies were already conducting feasibility studies and looking for suitable local partners.

Areas with wind-energy potential included West Nusa Tenggara, East Nusa Tenggara, North Sumatra, South Sumatra and Maluku, he added.

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GEOTHERMAL R&D BODY TO DEVELOP HOT-SPRING-POWERED GENERATOR
TOKYO, Oct 30 Asia Pulse - Geothermal Energy Research & Development Co. (GERD) plans to commercialize a small-scale generator that utilizes the heat of hot-spring water to produce electricity. GERD is a research company set up by electric power firms and other private concerns interested in utilizing geothermal energy.
For the project, GERD will develop a 50 kilowatt-class generator that utilizes the heat energy otherwise wasted from hot springs, providing enough electricity to power a small inn. The goal is to have a practical system ready by 2010 that costs some 25 million to 30 million yen (US$218,000-262,000).

Electricity will be generated by spinning a turbine using steam, but in this case the steam will be from a 70 per cent ammonia solution of water. Ammonia has a low enough boiling point to evaporate when exposed to the 80-100 degrees Celsius temperatures of a hot spring. After rotating the turbine, the ammonia steam will be dissolved back into water, transferring the heat to provide warm water for the baths and the kitchen.

(Nikkei)

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Garantie bij boren naar aardwarmte
30 september 2009, 12:02 | ANP
DEN HAAG (AFN) - De overheid geeft binnenkort garantie bij het boren naar aardwarmte. Zo'n regeling zou al op 1 april ingaan, maar de Europese Commissie heeft nu pas bepaald dat het niet gaat om ongeoorloofde staatssteun. Waarschijnlijk wordt de regeling, die het risico van mislukte boringen afdekt, in november van kracht.

Een woordvoerder van minister Maria van der Hoeven (Economische Zaken) heeft dat meegedeeld. Het ging om een initiatief van Van der Hoeven en minister Gerda Verburg (LNV). De regeling is vooral van belang voor glastuinders die aardwarmte willen benutten voor hun kassen.

De belangrijkste belemmering om aardwarmte te gebruiken zit niet in de directe kosten van het boren, maar in het risico dat de boring in een verkeerde aardlaag uitkomt. Dat risico is nauwelijks te verzekeren, omdat er weinig gegevens over zijn uit de praktijk. De overheid springt in dat gat met een regeling die 10 miljoen euro kost, en waarbij de mensen die naar aardwarmte boren een premie moeten betalen. Tuinders of andere ondernemers hebben dan nog een eigen risico, maar de Rabobank toonde zich al bereid hierin bij te springen.
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Zo'n regeling zou al op 1 april ingaan

WAHAHA

Probleem met aardwarmte, na een lange tijd van pompen wordt het daar kouder dus steeds minder warmte...
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Aardwarmte is hot!

Vrijdagmiddag belt een gemeentefunctionaris: 'Iemand heeft twee maanden geleden een opsporingsvergunning aangevraagd voor… aardwarmte; moest ik daar nog iets mee?' Antwoord: 'Ja, een tegenverzoek doen, en wel snel ook'.

Het gaat hard met aardwarmte. We hebben het dan over duurzaam gebruik van warmte op grotere diepte (zeg: 1500 tot 3500 meter). Na bodemwarmte heeft ook diepe aardwarmte belangstelling. Nederland beschikt over goede mogelijkheden. TNO heeft veel goed werk verricht, een aantal diepe boringen gedaan en twee maanden geleden het eerste aardwarmtenetwerk voor tuinders in Delft aangekondigd. Den Haag heeft plannen om 4000 huizen te verwarmen via Aardwarmte Den Haag, een vennootschap van de gemeente en belanghebbenden.

Internationale belangstelling

Dat is de internationale gemeenschap niet ontgaan. Naast vulkanische gebieden als Indonesië, IJsland en de Verenigde Staten, mag Nederland - als juist niet-actief geologisch gebied- zich verheugen in een warme belangstelling. Het Platform Geothermie bestaat niet langer uit de Nederlandse 'usual suspects', maar telt al meer dan 50 organisaties. Het aantal verzoeken voor opsporingsvergunningen is in de laatste jaren van 'op een hand te tellen' gestegen tot meer dan het tienvoudige. De meeste daarvan zijn aangevraagd door private ondernemers; een handjevol door overheden.

De regels voor opsporing van aardwarmte in Nederland zijn overzichtelijk. De geologische-, technische- en financiële informatie die moet worden verstrekt is niet omvangrijk; de toetsing niet zwaar. De vergunning van EZL&I kent een doorlooptijd van 7 a 8 maanden, waaraan, naast ontwikkelingskosten, geen bijzondere lasten zijn verbonden. Er is een subsidieprogramma dat de risico's van foutieve boringen beperkt en er zijn natuurlijk de gebruikelijke fiscale stimuleringsregelingen voor duurzame energie. In die 8 maanden wordt het verzoek gepubliceerd en kan gedurende 13 weken een tegenverzoek worden gedaan.

Exclusieve optie tot winning

Dat tegenverzoek is cruciaal. Als dat gebeurt, moet een keuze worden gemaakt tussen de aanvragers. Dat gebeurt in het belang van het doelmatig en voortvarend opsporen en winnen van aardwarmte. Dan staat de overheid meteen op 1-0. De procedure kent natuurlijk bezwaar en beroep, maar essentieel is dat je maar 1 keer een tegenverzoek kunt doen. Als je die kans voorbij laat gaan en een ander de opsporingsvergunning verkrijgt, kan hij bij een eventuele ontdekking zo doorrollen naar een winningsvergunning zonder dat iemand nog een tegenverzoek voor winning kan doen. Dan is het initiatief verloren; evenals de mogelijkheid om richting te geven aan het proces. De opsporingsvergunning geeft de houder tegen overzichtelijke kosten en risico's een exclusieve optie op winning.

Initiatief houden

Voor gemeenten dus iets om goed op te letten: als er een opsporingsvergunning wordt verleend, is de kans verkeken om zelf iets te doen met een belangrijke, lokale duurzame energiebron. Dat is moeilijk uit te leggen als inwoners later NUMBY (Not Under My Back-Yard) gevoelens krijgen of - beter nog - de gemeente toch het initiatief van Den Haag en TNO wil volgen.

Want een gemeente kan natuurlijk ook zelf het initiatief in handen nemen en een opsporingsvergunning aanvragen als daartoe aanleiding is. Als dat gebeurt in vennootschappelijke vorm kunnen eventuele ondernemers later in die vennootschap participeren, maar dan wel op de voorwaarden die de gemeente stelt.

Dat werd vrijdag dus nog een drukke middag.

Weero Koster is advocaat/partner van Norton Rose LLP


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Tuinders in Kampen over op aardwarmte
Gepubliceerd op 28 apr 2011 om 16:08 | Views: 1

KAMPEN (AFN) - Tuinders in Overijssel gaan hun kassen verwarmen met aardwarmte, ofwel warm water dat wordt opgepompt uit de diepe ondergrond. Gedeputeerde Theo Rietkerk gaf donderdag in Kampen de aftrap voor het eerste project in de provincie en kondigde aan bereid te zijn om ook voor volgende initiatieven een deel van de financiering te verzorgen en een deel van de risico's af te dekken.

Het gebruik van aardwarmte of wel geothermie is een vorm van duurzame energie, die ook door het Rijk wordt ondersteund. Minister Maxime Verhagen (Economische Zaken) stuurde vorige week een actieplan naar de Tweede Kamer. Hij wil de garantieregeling bij de boringen verbeteren en aardwarmte ook stimuleren met de nieuwe regeling voor exploitatiesubsidies voor duurzame energie.

Voor het eerste project in Overijssel hebben drie tuinders de krachten gebundeld in het Aardwarmtecluster bv. Het project omvat 17,5 hectare en de warmte komt van bijna twee kilometer diep. Jaarlijks wordt zo 5 miljoen kubieke meter gas bespaard.
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Geothermal power will bring CNY 70 billion market potential to China

Mr Li Yuanpu executive member of the Chinese Renewable Energy Society said geothermal energy will supply heating and air conditioning for 350 million square meters of indoor areas in China during the 12th Five-Year Plan period (2011-2015).

He said that "As measured by 200 yuan in investments per square meter, the total 350 million square meters will boast a market potential of CNY 70 billion."

According to the CRES, sales of geothermal power pumps have topped CNY 8 billion in China with an annual growth rate of 20%.

To date, geothermal energy has supplied heating and air conditioning to 2,236 construction projects. Heating provided by geothermal power pumps has totaled 140 million square meters in area.

Mr Guan Fengjun director of the Department of Geological Environment with the Ministry of Land and Resources said "The use of geothermal power is expected to reach an equivalent of 68.8 million metric tonnes of coal by 2015 or about 1.7% of the nation's total power consumption."

Mr Guan said the ministry is actively promoting the development of geothermal energy and will soon launch a national survey on the use of geothermal power.

(Sourced from Xinhua)
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Construction started for 1200 MW Hai Duong thermal power plant

VNS reported that a massive ceremony to celebrate the biggest foreign direct investment in a power project, the Hai Duong 1,200 MW thermal power plant, was held in Kim Mon District, Hai Duong Province.

The Hai Duong power plant will have two 600 MW steam turbines run by JAKS Hai Duong Power Company Limited under the Malaysia based JAKS Resources Berhad Group with a total capital investment of USD 2.25 billion.

Covering an area more than 300 hectare spread over Phuc Thanh, Quang Trung and Le Ninh communes in Kim Mon District, construction for the plant is scheduled to start in June 2012 with the first turbine expected to be operational by the fourth quarter of 2016 and the other by the second quarter of 2017.

At the ceremony, general director of the group Ms Andy Ang Lam Poah said the plant will operate under the BOT model as an independent power producer and will be transferred to the Ministry of Industry and Trade after 25 years of operation.
When it opens, the plant will use coal provided by Viet Nam National Coal and Mineral Industries Holdings Limited. Hai Duong BOT Power Plant was approved by the Prime Minister in September 2008 and is part of Viet Nam's Power Planning Outline VI initiative.

(Sourced from VNS)
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GVK Power eyes 7500 MW thermal power capacity by 2016-17

PTI reported that GVK Power and Infrastructure, the flagship company of Hyderabad based GVK group is planning to have 7,500 MW thermal power generation capacities by 2016-17.

Mr Issac George CFO of GVK Power said "The Plan is to have a thermal power capacity of 7,500 MW. It is at the drawing board currently but we aim to achieve this capacity in next 5 years."

He added that to run the plants the company would import 20 million tonnes of coal a year from GVK Group's intended acquisition of assets of Australia Hancock Coal. The company which has gas based 901 MW power generation capacities is expecting to commission its first thermal plant of 540 MW in Punjab in 2012-13.

He added that moreover, the move is part of a long-term growth plan of the company, which is aiming to have about 12,000 MW power generation capacities by 2016-17.

Currently, new units of 3,530 MW power generation capacities are at various stages of construction and development including 1,390 MW hydro power units.

(Sourced from PTI)
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Dr Farooq update on geo thermal energy

Dr Farooq Abdullah minister of new and renewable energy informed the Lok Sabha that during the last three years, the States of Jammu & Kashmir, Chhattisgarh, Uttarakhand, Andhra Pradesh, Maharashtra, Gujarat and West Bengal have taken steps to harness geo thermal energy in their respective states. Geo-thermal resource assessment studies have also been undertaken by Ministry of New and Renewable Energy at various potential sites through National Geophysical Research Institute Hyderabad.

While no Geo-Thermal Energy Power plant has been set up in the country so far, the MNRE has prepared draft policy and guidelines to facilitate preparation and implementation of an action plan to set up projects for utilization of geo-thermal energy No specific assistance has been sought from any particular country. However India has Memorandum of Understandings on co-operation in Renewable Energy including Geothermal Energy with several countries.

Source - PIB

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Maibarara Geothermal to expand geothermal power plant

Manila Standard Today reported that Maibarara Geothermal Inc will drill two more geothermal wells in 2013 to expand the capacity of the 20 MW Maibarara geothermal power project in Sto Tomas in Batangas.

Mr Jay Layug energy undersecretary of Philippines told reporters that while the capacity of the Maibarara geothermal field was estimated at only 20 MW, the drilling could show potentially higher geothermal steam in the area. He added that "They are set to drill two more wells and we will see how much more they can produce. Normally the cost for geothermal is between USD 4 million and USD 5 million. So the two wells would cost USD 10 million. The commitment is to drill two wells next year to determine additional capacity."

Mr Layug said that "It is the first project under the Renewable Energy Act that we provided or granted declaration of commerciality. It's 20 MW. It's hopeful that it can start producing by 2013 and provide more electricity through renewable energy to the Luzon grid."

The declaration of commerciality meant that after a two year feasibility study, the company discovered the resources were available and commercially feasible. It also indicated that the government allowed the company to proceed to build the power plant.

Mr Layug said that this was the first geothermal power plant to be built since Energy Development Corporation's last project in 2006. He added that "What's key here is it's the first geothermal project operated by a Philippine private company that makes it more significant. Because used to belong to the government now, privatized."

Source - Manila Standard Today
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Tweede bron aardwarmte in IJsselmuiden

Door: redactie
16-8-12 - 17:45 bron: ANP
Tuinders in IJsselmuiden gaan een tweede aardwarmtebron openen. Dat meldden ze tijdens een werkbezoek van staatssecretaris Henk Bleker (Landbouw).

Sinds maart is er de eerste van mogelijk zeven bronnen operationeel. Warm water dat vanaf 1,9 kilometer diepte wordt opgepompt, stroomt er door de kassen. De groep tuinders die een tweede bron willen slaan, dreigde een door het ministerie al toegezegde subsidie van 2 miljoen euro mis te lopen vanwege vertraging in de voorbereidingen. Bleker zegde toe dat de vertraging deze subsidie niet in de weg zal staan.

Aan de subsidie was aanvankelijk een deadline gekoppeld. Dat betekende dat het project al in februari 2013 opgeleverd moest worden. Mede door problemen tijdens de EHEC-crisis vorig jaar ontstond de vertraging. 'Dit is een project met veel onzekerheden. Het zou van de dolle zijn als dit vanwege een termijn van een paar maanden door de grond zou zakken', zei Bleker. De provincie Overijssel stelt een lening van 5 miljoen euro beschikbaar, zei gedeputeerde Theo Rietkerk.

De boor moet dit jaar nog de grond in. De warmtebron moet circa 20 hectare aan kassen kunnen verwarmen.
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Napels wil energie pompen uit Vesuvius

De Italiaanse stad Napels wil geothermische energie halen uit de vulkaan Vesuvius, voor verwarming en voor de productie van stroom.

Napels ligt aan de voet van de Vesuvius en heeft aan de andere kant van de stad nog een tweede vulkanisch gebied, de Campi Flegrei. De stad wil de warme ondergrondse temperaturen gebruiken om huizen te verwarmen en stroom op te wekken.

Rijkelijke energiebron
'We willen als pilootproject een centrale opzetten die geïntegreerd is met andere energiebronnen, zoals zonne-energie en vloeibare biomassa, zoals gerecycleerde frituurolie en algen', zegt Antonio Luongo, wethouder voor Energie bij de aankondiging op een conferentie in Napels. 'Geothermische energie is een van onze meest rijkelijke hernieuwbare energiebronnen. Volgens deskundigen is de vulkanische regio gelijkwaardig aan vier grote kerncentrales.'

Napels wil de energie in een eerste fase gebruiken voor verwarming, en in een volgende fase ook om elektriciteit te produceren. De installaties moeten betaald worden met geld van private investeerders en middelen van de Europese Unie.


www.ad.nl/ad/nl/1013/Buitenland/artic...
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Contact Energy Ltd.’s Te Mihi Power Station Harnesses Sustainable Geothermal Energy

Te Mihi Power Station is a two-unit 166-MW geothermal plant currently undergoing commissioning on New Zealand’s North Island. It replaces the Wairakei Power Station constructed in 1958—but with a much smaller environmental footprint. The double flash technology selected produces ~25% more power from the same amount of geothermal fluid that is currently used at Wairakei. For its continuing commitment to renewable geothermal energy, Contact Energy Ltd.’s Te Mihi Power Station is the winner of POWER’s 2013 Marmaduke Award for excellence in power plant problem-solving. The award is named for Marmaduke Surfaceblow, the fictional marine engineer and plant troubleshooter par excellence.

Contact Energy Ltd. (Contact) is one of New Zealand’s leading developers of sustainable power generation systems, with a diverse portfolio of geothermal, natural gas, wind, and hydroelectric assets. In terms of revenue, Contact is one of five large New Zealand power companies. Contact owns and operates 10 plants located throughout the country, producing ~25% of New Zealand’s electricity demand. Four of its facilities are geothermal plants located in the Central North Island.

In early 2007, Contact announced plans to invest up to $1 billion in the construction of new geothermal plants in the Taupo region, located near the center of the North Island. (All amounts in US$; US$1 = NZ$1.28 at press time.) The latest addition to Contact’s renewable portfolio is the two-unit 166-MW (159-MW net) Te Mihi Power Station (Te Mihi).

Contact CEO Dennis Barnes says its investment in Te Mihi reflects the company’s view that geothermal is New Zealand’s most cost-effective new baseload generation. Barnes identified the importance of Te Mihi to ratepayers when he said, “The additional 114 megawatts is expected to be required by the market by 2013 as economic growth resumes and will also contribute to lowering Contact’s average cost of generation.” The total cost of Te Mihi is estimated to be close to $623 million. A second project at Tauhara is in the development pipeline, with other projects seeking permits or in the reservoir exploration phase.

To develop Te Mihi, Contact engaged the McConnell Dowell Constructors Ltd., SNC-Lavalin, and Parsons Brinckerhoff New Zealand joint venture (MSP JV) to build Te Mihi. The engineering, procurement, and construction (EPC) contract was signed with MSP JV in February 2011 for two 83-MW geothermal power units to be constructed 5 kilometers (km) from the existing Wairakei geothermal power station.

Long-Term Investment

Taupo is the center of volcanic and geothermal activity on the North Island (Taupo Volcanic Zone), and Lake Taupo is a popular tourist destination. Taupo is also the region where geothermal energy has been the principal source of electricity generation for the North Island since the 1950s. Today, geothermal energy satisfies almost 15% of the entire country’s electricity needs. All of the country’s geothermal plants are located on the North Island. Hydroelectric power supplies about 98% of total South Island demand. A single HVDC Inter-Island transmission line with a capacity of 1,200 MW (by the end of 2013) interconnects the two islands.

The oldest geothermal plant in the Taupo region is the 66-MW Wairakei A Power Station, constructed in 1958, the first of its type in the world to use wet steam in a single flash process to produce electricity. The plant’s single flash system has reliably served residents, but increasing maintenance costs and emerging environmental issues have shown the plant was nearing the end of its useful life. However, the Wairakei steam field is predicted to be able to supply steam for electricity generation for many more decades.

Wairakei uses once-through river cooling of its condensers and discharges steam condensate into the Waikato River, which flows down from Lake Taupo. At present, the Wairakei power station uses a cooling system that relies on drawing water from the Waikato River, mixing it with steam condensate that has been used to power the turbines, and then discharging that stream of cooling water back to the river. The result has been warmer water and the deposit of geothermal trace elements in the river water.
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New Design Solves Scaling Problems on Geothermal Control Valves

11/01/2013 | Reynir S. Atlason and Runar Unnthorsson

Scaling is one of the most frequently occurring problems in geothermal power plants and can prohibit the control of well flow if it builds in the well or wellhead. At HS Energy on the Reykjanes Peninsula in Iceland, the problem was minimized utilizing a design developed by a veteran plant worker. The solution could not have been implemented without an open-minded leader who was ready to listen and push forward with the remedy. In this particular case, Erlendur Guðmundsson’s idea required the backing of HS Energy Vice President Albert L. Albertsson to get the ball rolling.

The solution that was developed is a new valve, referred to as Elli-valve, which allows for better flow control and easier cleaning. It also has been shown to have economical advantages over other valves on the market. This solution could be useful in other geothermal power plants dealing with similar issues, but it also demonstrates how the ingenuity of the people most familiar with an issue, such as the plant workers, can be used to provide effective solutions to problems in any plant.

The Reykjanes Geothermal Field

On the Icelandic Reykjanes Peninsula, HS Energy operates two geothermal power plants, Svartsengi and Reykjanes. Svartsengi currently produces 46.4 MWe and 150 MWt. The high-temperature area stretches over 2 square kilometers. The Svartsengi geothermal power plant was constructed in small phases beginning in 1974 and stretching out to 2000. Reykjanes geothermal power plant went into production in 2006. It currently operates two 50-MW dual-flow turbines delivering approximately 100 MWe. Both plants are relatively close to the ocean, which results in brine rich in Na, Cl, K, SiO2 and SO4. A detailed description of the brine can be found in Table 1.

At Svartsengi, the average flow rate is approximately 226 kg/s (as reported in a 2000 study) where steam is 32% of the flow at 5.5 bar separation pressure, and temperatures have been shown to be around 240C. At Reykjanes, temperatures typically run between 250C and 320C.

Studies have shown that the chemical composition of the brine increases certain problems in the control valves. (Interestingly, the scaling problem experienced in the control valves at HS Energy has not been seen at such magnitude at other geothermal power plants located relatively nearby in Iceland, namely Hellisheidi and Nesjavellir—likely because the chemical composition of the brine is very different at those other locations.) Previous studies conducted on surface pipes in the Reykjanes area, operating at pressures of 20 and 5 bar-g, have recorded scale forming at a rate of 0.1 to 0.5 mm in 30 days or roughly 1.2 mm to 6 mm per year. Scaling eventually leads to difficulties in controlling the flow from the well.

Types of Valves

A geothermal wellhead assembly consists of many different valves with various functions. Most of the valves are not operated regularly. Many valves are used only when necessary to divert the flow from the collection pipe system, close the hole if it is not used in production, or when isolation is necessary for repairs.

The control valve is regularly operated, however, where its purpose is to control the flow of steam and brine from the well. Controlling the flow from the well is essential for efficient operation of a geothermal power plant. Choosing the right control valve is therefore of great importance.
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