Did you know… three of the largest geothermal power plants in the world are found in Indonesia?

Did you know… three of the largest geothermal power plants in the world are found in Indonesia?

Indonesia is home to beautiful tropical islands, a rich and vibrant culture, and geothermal power plants! The first exploration geothermal wells were drilled in the 1920s, but the first power production did not start until 1978 at Kamojang. Today, there are over 17 producing fields, including three of the world’s largest.

The biggest is called Gunung Salak, which is located 70 km from Jakarta, the Indonesian capital, on the island of Java with an installed capacity of 377 MW. The field was drilled and put into production by Unocal in 1994 and later acquired by Chevron in 2005. In December of 2016, the field was taken over by Star Energy. Electricity is generated and sold by the state-owned company, PLN.

The second biggest field is Sarulla. It generates 330 MW of electricity and is based in the Tapanuli Utara district of the North Sumatra Province. The project is owned by the Sarulla Operations Limited consortium and electricity is generated  by three units of 110 MW each. The first unit was commissioned in March of 2017 and the second in October of the same year. The third unit was commissioned in May of 2018. Geothermal power supplies electricity to approximately 2.1 million homes.

The third largest geothermal project is Darajat which is located 270 km southeast of Jakarata near Garut in the Parirwangi District of West Java. The installed capacity is 271 MW and the resource was initially developed by Amoseas, later acquired by Chevron and since 2016 it has been run by Star Energy. The first power generation commenced in 1994, with the commissioning of a 55 MW unit. A 95 MW unit was commissioned in 2000 and a third unit capable of generating 121 MW was commissioned in 2007.

It is no wonder Indonesia is the second largest producer of geothermal energy in the world, with huge potential for additional growth.





Did you know… Italy is home to the oldest geothermal plant in the world?

Did you know… Italy is home to the oldest geothermal plant in the world?

The first geothermal plant in the world is located in Tuscany, Italy.

The Larderello geothermal plant was constructed in the early twentieth century thanks to Prince Piero Ginori Conti of Trevignano. Through his work in the processing of boric acid, Conti found his way into the world of geothermal energy and, in 1904, created the first geothermal energy generator.

Stationed in the Larderello dry steam field, his generator could produce up to 10 kW of energy. It also powered five light bulbs.

From there, Larderello’s geothermal potential expanded. In 1911, in an area called Devil’s Valley, construction of a geothermal plant was begun. The plant was completed in 1913.

That first plant, Larderello 1, had a capacity of 250 kW and could produce 2750 kW of electricity. That electricity powered the Italian railway system as well as the nearby villages of Volterra and Larderello.

The original plant has been gradually expanded over the years and now consists of 34 plants, which are operated by the Italian company Enel Green Power, or EGP. The site has a capacity of 800MW, which has resulted in Italy becoming the sixth-largest geothermal energy producer in the world.



Did you know… Mount Erebus is the southernmost volcano in the world?

Did you know... Mount Erebus is the southernmost volcano in the world?

Located on the western half of Ross Island stands Mount Erebus – the tallest active volcano in Antarctica. Mt Erebus is the largest and only active center of the four volcanic peaks (Mt. Bird, Mt. Terra Nova, and Mt. Terror) that make up the triangular-shaped island.

Erebus is the southernmost volcano in the world, and it is most famous for its lava lake and ice fumaroles. Sitting on a relatively thin continental crust, molten magma easily erupts on the surface, having originated from deep in the Earth’s interior. Continuous emissions of gas and steam provide just the right conditions for building towering columns of ice known as ice fumaroles. Volcanic eruptions are frequent, but the blasts are relatively mild and of the Strombolian-type.

The stratovolcano is 3794 meters (12,447 feet) above sea level. The average summit temperature is around -20˚C (-4˚F) during the summer and -50˚C (-58˚F) in the winter.

Erebus glacier extends down the lower flanks of the cone. Where it flows into McMurdo Sound at sea level, an impressive 11-kilometer (~ 7 mile) long ice tongue protrudes into the sea as the annual snowfall exceeds the annual snowmelt. The ice tongue ranges 50 to 300 m (~164 to 984 ft) in thickness and stands 10 meters (33 feet) above the waterline.

Mount Erebus was first discovered and seen erupting by Captain James Ross, an explorer, in 1841 when he and his crew sailed past the island. It was later scaled by members of an expedition led by Ernest Shackleton in 1908. However, in the following 100 years, it has been rarely visited.

All photo credits to Phil Wannamaker.




Did you know… there is a submarine volcano in Antarctica?

Did you know… there is a submarine volcano in Antarctica?

Deception Island, Antarctica is home to an active submarine volcano which has created a large volcanic crater in the middle of the South Shetland Islands.

The total land area of the island is 98.5 km2(~38.0 mi2), with a diameter of 15 km (~9.3 mi). The island rises up to 539 m (~1768.4 ft) above the sea level. More than 57% of the island is covered by permanent glaciers.

The average annual air temperature is -3˚C (26.6˚F); however, temperatures can range from a high of 11˚C to a chilly -28˚C (51.8˚F to -18.4˚F.)

The island’s geothermal heat is found just below the surface. This means visitors can dig a shallow depression into black sand beaches to enjoy the warmth - especially appealing after taking a

Technically, there are no official hot springs on the island, however, along the shoreline of Pendulum Cove, there are thermal springs with temperatures over 70˚C (158˚F). Due to the mixture the cold and hot water, a natural hot tub is created.

But before you jump in, consult a trained expert or experienced expedition guide. They know which areas are safe for a relaxing soak in the steamy water.

Stay tuned to learn about the other active volcano, Erebus.




Did you know… Alaska uses geothermal energy to produce electricity?

Did you know… Alaska uses geothermal energy to produce electricity?

It might seem highly unlikely that geothermal energy could be harnessed in the Arctic climate of Alaska considering HOT water is required. However, this is not the case! Geothermal reservoirs can be found almost anywhere in the world. In fact, Alaska has 97 known thermal springs and is one of eight states to use geothermal energy to produce electricity. The first geothermal power plant in Alaska launched in 2006 at Chena Hot Springs and can generate up to 730 kilowatts of power. It is located in the Interior hot springs geothermal region.

The Chena Hot Springs Resort uses geothermal energy in many different ways. The geothermal energy generated supplies power and heat to its greenhouses, swimming pools, and other facilities. In order to produce the power, a binary plant, that runs on the organic Rankine cycle, is used with a generating capacity of 680 kW. The plant runs on 165˚F (~73.9˚C) water meaning the geothermal power plant generates electricity at the lowest temperature in the world. The resort also has a 16-ton absorption chiller, which uses geothermal energy to keep their outdoor ice museum frozen all year round.

Including the Interior hot springs, there are two other active geothermal regions in Alaska – the Southeast hot springs and the “Ring of Fire” volcanoes. The Interior hot springs run from the Yukon Territory in Canada to the Seward Peninsula in Alaska. The “Ring of Fire” volcanoes include the Alaska Peninsula, Mount Edgecumbe, the Aleutians, and the Wrangell Mountains.

Currently, the Alaska Center for Energy and Power, or ACEP, is working with landowners, multiple utilities, and communities to assess resources and evaluate options for the development of geothermal energy in multiple parts of the state.





Did you know… there is a geyser on one of Saturn’s moons?

Did you know... there is a geyser on one of Saturn's moons?

And not just one, but over 100 huge water-vapor geysers occur at the south pole of Saturn’s moon Enceladus. They are believed to come from an ocean beneath the moon’s outer ice crust in which water comes to the surface through cracks in the ice that are called tiger stripes. Due to Enceladus’ tenuous atmosphere, the water vapor re-freezes and forms ice particles that fall back down to the moon’s surface, covering it in fresh ice that makes Enceladus the brightest object amongst all the planets.

More tantalizing is the scale of geysering. The plumes are the tallest known anywhere in the solar system, rising tens of kilometers above the surface of the moon. They are now known to be the source of Saturn’s E-ring, and the eruptions might be triggered by tidal forces. Remarkably, Enceladus is only about 500 km in diameter. The photographs from the Cassini mission from 2006 to 2017 have provided amazing insights about extraordinary geological activity on this small icy moon.



Geyser plumes on Enceladus (Courtesy NASA/JPL-Caltech).  https://solarsystem.nasa.gov/resources/806/bursting-at-the-seams-the-geyser-basin-of-enceladus/

Enceladus geysers feed Saturn’s E-ring (Courtesy NASA/JPL-Caltech). https://www.jpl.nasa.gov/images/ghostly-fingers-of-enceladus

Did you know… Pamukkale is a travel HOT spot?

Did you know... Pamukkale is a travel HOT spot?

Pamukkale is a western Turkish town known for the mineral-rich thermal waters that cascade over steep, white terraces that reach over 100 meters (~330 feet) high. Across the terraces, there are a total of 17 hot springs, which range in temperature from 35-100 degrees Celsius (95-212 degrees Fahrenheit) year-round.  The name in Turkish means “cotton castle” as it resembles the cotton plantations in central Turkey.

However, the white terraces are not cotton – they’re travertine rock! Travertine is a form of limestone that is deposited over time by mineral waters, most commonly, hot springs. The mass of hot springs sources in the area produces high amounts of calcium carbonate in the water so when the water hits the open air, it becomes white travertine rock.

Before it was Pamukkale, the site used to be the lively Greco-Roman city Hierapolis. Hierapolis was a spa city founded in 190 BC. Just like today, it was one of Turkey’s most popular hot springs. The ruins of the city are well preserved and hold what is known as Cleopatra’s pool, who is said to have bathed there, along with many other historically famous people.

The hot springs are open to the public to swim and relax in, and they have been known to be great for healing.





Did you know… that Paris has used geothermal energy to heat the homes of more than 2 million people?

Did you know... that Paris has used geothermal energy to heat the homes of more than 2 million people?

You might not think that Paris, the city of love, would be a major producer of geothermal energy – but it is! Paris has been using geothermal energy to heat houses since 1969.

Under the famous city are two deep aquifers containing hot water. Since 1969, Paris has been working on many geothermal projects. Today, there are around fifty supply networks in the city that heat almost 250,000 homes.

The main aquifer, the Dogger, is about 1,500-2,000 meters (~4,900-6,600 feet) deep. The rock that hosts the aquifer is 150-170 million years old and is made of limestone. It has a temperature of about 60 degrees Celsius. While the Dogger is full of mineral salts that make produced water unfit for consumption, the heat can be used for district heating. This geothermal resource supplies energy to buildings in the northern, eastern, and southern parts of Paris, but to the west it falls below a threshold temperature that makes drilling and production uneconomic.

Currently, SIPPEREC (the Paris intercommunal union for energy and communication networks) is exploring the idea of drilling into the Triassic rock layer, which underlies the Dogger at 2,100 meters (~6,870 feet) depth. The temperature of the water at this level is about 80 degrees Celsius – 20 degrees higher than the Dogger. If successful, utilizing the Triassic layer would allow development in the western part of the Paris region but full-scale exploration awaits approval from regulatory authorities and the state.

As of 2020, drilling into the Dogger costs about 5 million euros per well. Of course, drilling deeper costs more, and the cost of drilling into the Triassic layer is about 9 million euros per well. However, because of the hotter water temperature, production here could be cheaper as less water would be required. SIPPEREC says that network users' charge could be lowered as well.

The new heating networks are scheduled for completion in November of this year with the benefit of conserving annual emissions of 30,000 tonnes of CO2.






Did you know… geothermal wells can be highly deviated too?

Did you know... geothermal wells can be highly deviated too?

Just as in the oil industry, the first geothermal wells were all vertical, which remains common practice mainly because it is cost-effective. The maximum depth is typically about 10,000 feet (3 km). Deviated geothermal wells have been drilled too, extending laterally over horizontal distances up to about 5,000 feet (1.5 km) and dipping at angles of less than 45° as measured from the vertical. In most geothermal fields, the rock formations are made up of volcanic and sedimentary rocks.

New groundbreaking developments are now happening in the geothermal industry borrowing methods used for unconventional hydrocarbon development. Recently, a well having a long horizontal leg was drilled for the DEEP geothermal project in the Williston Basin, Saskatchewan, Canada.

The type of rocks being drilled into for geothermal development are relevant because up until now very few have reservoirs hosted by granitic rock, which is abrasive and hard on wear and tear of downhole equipment. Examples of such wells include 14-2 at Roosevelt Hot Springs, WD-1A at Kakkonda, Habanero 1 in the Cooper Basin, 33A-7 at Coso and OTN-3 in Finland. Of these, WD-1A has the hottest bottom hole temperature (~500°C), and OTN-3 is the deepest, but for this rock type, highly deviated wells are absent.

The new deep well at Utah FORGE, 16A(78)-32 is thus notable. It shows that the drilling of sub-horizontal well trajectories in granitoid are achievable. Such highly deviated wells are required for EGS wells in order to intersect a large number of sub-vertical fractures and to maximize energy production.

Figure showing the geothermal well profiles, host rocks and deviation angles: conventional wells in red; sedimentary basin wells in green (Saskatchewan, Canada; Groß Schönebeck, Germany); metamorphic-plutonic well in blue (Helsinki, Finland); granitoid wells in black (Roosevelt Hot Springs, Utah; Kakkonda, Japan; Cooper Basin, Australia; Soultz-sous-Forêts, France; Coso, California); granitoid well in pink (Utah FORGE).  


Ayling et al. 2016, Geothermics 63, 15-26. https://www.sciencedirect.com/science/article/pii/S0375650515000395

Kwiatek et al. 2019, Science Advances,5 https://www.science.org/doi/10.1126/sciadv.aav7224

Ledésert & Hébert 2012,  Heat Exchangers - Basics Design Applications, 447-504, https://doi.org/10.5772/34276

Muraoka et al. 1998, Geothermics, 27:507-535. https://www.sciencedirect.com/science/article/pii/S0375650598000315


Sabin et al 2016, Proceedings Stanford Geothermal Workshop (https://pangea.stanford.edu/ERE/pdf/IGAstandard/SGW/2016/Sabin.pdf)

Zimmerman et al. 2010, Geothermics, 39, 59-69 (https://www.sciencedirect.com/science/article/pii/S0375650509000674)

Did you know… that the first wells were drilled over 2000 years ago?

Did you know that the first wells were drilled over 2000 years ago?

Drilling is an ancient technology and it has long been used to explore for natural resources and to produce fluids such as water, brine, oil and gas that occur underground. The Chinese drilled shallow wells over 2000 years ago to produce brine. The first oil wells were drilled in the 1800s and up through the early 1900s, wells were vertical and limited to depths of a few hundred to a couple of thousand feet. By the 1970s, depth records were being broken starting with Bertha Rogers No. 1 which was drilled to over 31,000 feet (9.5 km) to explore for gas in the Anadarko basin, Oklahoma, USA. In 1979, the Kola Superdeep scientific well in Russia was drilled to over 40,000 feet (12.2 km), making it the deepest well in the world.  In 2009, the deepest oil well was completed to 35,000 feet (10.6 km) from the Deepwater Horizon platform in the Gulf of Mexico.

The idea of drilling a slanted deviated well by directional drilling was realized in the 1930s. Today, the drilling of highly deviated wells is commonplace in the exploration and production of oil and gas reservoirs. The Chayvo oil field in Russia is the site of several record-breaking deviated wells that are drilled to depths of about 3,000 feet (0.9 km) with a long horizontal reach exceeding 40,000 feet, the longest of which is O-14. For comparison, geothermal wells are generally drilled to no more than 10,000 feet (3 km), and if deviated, they are done so at modest angles of less than 45°.

There are several reasons for drilling deviated wells such as increasing the section or length of well interval through rocks that are rich in oil (or gas). In some cases, there are obstacles (e.g., town or lake), which means the resource has to be accessed from the side rather than vertically from the surface. In other cases, there are logistical advantages to clustering a number of deviated wells on a single pad as is common in offshore oil platforms.

Figure shows the depth ranges of the deepest and longest wells in comparison to wells that are commonly drilled in geothermal production fields.