Overview
The Hellisheiði Power Station stands as the largest geothermal power facility in Iceland and ranks as the eighth-largest geothermal power station globally. Located in the Hengill geothermal field in southwest Iceland, the plant plays a critical role in the nation's energy infrastructure. The facility is situated approximately 11 km from the Nesjavellir Geothermal Power Station, forming a key component of the regional energy network. Hellisheiði is owned and operated by ON Power, which functions as a subsidiary of Reykjavík Energy, linking the plant’s operations directly to the capital city's energy management structure.
The power station has an installed electrical capacity of 303 MW. In addition to its electrical output, the facility provides significant thermal energy, delivering 200 MWth of hot water specifically for Reykjavík's district heating system. This dual output highlights the plant's importance not only for electricity generation but also for the thermal comfort and energy efficiency of the capital region. The plant has been operational since its commissioning in 2006, marking a major expansion in Iceland's geothermal exploitation capabilities. As an operational geothermal facility, Hellisheiði continues to leverage the natural heat resources of the Hengill area to sustain its production levels.
Why it matters
Hellisheiði Power Station holds a prominent position in the global renewable energy landscape as the eighth-largest geothermal power station in the world. Within its domestic context, it stands as the largest geothermal facility in Iceland, marking a significant milestone in the nation’s exploitation of its subterranean thermal resources. The plant’s scale is not merely a function of electrical output but also reflects its critical role in the integrated energy system of the capital region. With an installed electrical capacity of 303 MW, the station provides a substantial portion of the electricity demand for Reykjavík and its surrounding areas, contributing to the stability of the national grid. This capacity places Hellisheiði among the most significant single-site geothermal producers globally, underscoring Iceland’s leadership in geothermal energy utilization.
Integrated Energy Supply for Reykjavík
Beyond electricity generation, Hellisheiði is a cornerstone of Reykjavík’s district heating infrastructure. The facility produces 200 MWth of hot water, which is distributed to homes and businesses across the capital region. This dual-output model—generating both electricity and thermal energy—enhances the overall efficiency of the geothermal resource. By capturing waste heat from the power generation process, the plant reduces the need for separate heating plants, thereby lowering overall energy consumption and greenhouse gas emissions. The integration of Hellisheiði into Reykjavík’s heating network ensures a reliable and sustainable thermal supply, which is particularly valuable during the harsh winter months. This synergy between power and heat production exemplifies the advantages of geothermal energy in densely populated areas with high thermal demand.
Regional Context and Comparative Scale
The location of Hellisheiði in the Hengill geothermal field, southwest Iceland, places it in close proximity to another major facility, the Nesjavellir Geothermal Power Station, located just 11 km away. This geographic clustering of large-scale geothermal plants highlights the richness of the Hengill field and the strategic planning involved in maximizing resource extraction. The presence of two major stations in such a small area allows for shared infrastructure and coordinated operations, further enhancing the efficiency of the region’s energy supply. Hellisheiði’s status as the largest geothermal plant in Iceland distinguishes it from other national facilities, reflecting its critical importance to the country’s energy security. The plant’s operational success, managed by ON Power, a subsidiary of Reykjavík Energy, demonstrates the effectiveness of public-private partnerships in developing large-scale renewable energy projects.
How does Hellisheiði produce energy?
Hellisheiði utilizes flash steam technology to convert geothermal energy into electricity, operating as the largest geothermal facility in Iceland and the eighth-largest globally. The plant is situated in the Hengill geothermal field in southwest Iceland, located 11 km from the Nesjavellir Geothermal Power Station. The station is owned and operated by ON Power, which is a subsidiary of Reykjavík Energy.
Flash Steam Technology and Turbine Configuration
The power generation process relies on extracting high-temperature geothermal fluids from the Hengill field. In a flash steam system, hot water under high pressure is brought to the surface and passed through separators. As the pressure drops, a portion of the water "flashes" into steam. This steam drives turbines connected to generators, while the remaining brine is often reinjected or used for secondary power extraction. The Hellisheiði plant features a total electrical capacity of 303 MW. The turbine configuration includes multiple units to optimize efficiency and output stability. The grounding data specifies the presence of 45 MW and 33 MW turbine units within the plant's layout. These units work in tandem to harness the variable flow and temperature of the geothermal reservoir, ensuring consistent power delivery to the national grid.
Integration with District Heating
In addition to electricity generation, Hellisheiði plays a critical role in the thermal energy supply for the capital region. The plant produces 200 MWth of hot water specifically for Reykjavík's district heating network. This dual-output model maximizes the energy yield from the geothermal source. After the steam has passed through the turbines, the residual heat in the brine is captured and distributed via insulated pipelines to homes and businesses in Reykjavík. This integration reduces the need for separate heating infrastructure and enhances the overall thermal efficiency of the Hengill geothermal field. The operational status of the plant is currently active, having been commissioned in 2006. The combination of 303 MW of electrical power and 200 MWth of thermal output makes Hellisheiði a cornerstone of Iceland's renewable energy infrastructure.
History
The Hellisheiði Power Station began operations in 2006, establishing itself as the largest geothermal power station in Iceland and the eighth-largest in the world. Located in Hengill, southwest Iceland, the facility is situated 11 km from the Nesjavellir Geothermal Power Station. The plant is owned and operated by ON Power, a subsidiary of Reykjavík Energy. Upon commissioning, the station provided a significant boost to the regional energy mix, contributing 303 MW of electricity and 200 MWth of hot water for Reykjavík's district heating network. The development of Hellisheiði represented a major expansion of Iceland's geothermal infrastructure, leveraging the abundant resources of the Hengill volcanic system to meet growing domestic demand for both power and thermal energy.
Construction and Expansion Phases
The development of the Hellisheiði Power Station involved a structured construction process leading up to its full operational status. The project was designed to integrate both electricity generation and district heating capabilities, ensuring a dual-output model that maximized the efficiency of the geothermal resources. The addition of turbines and the integration of the hot water plant were critical components of the initial build-out, allowing the facility to reach its full capacity of 303 MWe and 200 MWth. The timeline below outlines the key phases of construction and commissioning from the start of operations in 2006 through the subsequent years of stabilization and expansion up to 2011.
| Year | Event |
|---|---|
| 2006 | Commissioning of the Hellisheiði Power Station; initial output of 303 MWe and 200 MWth. |
| 2007–2011 | Continued operational stabilization and integration of turbine units and hot water plant infrastructure. |
During the years following its 2006 commissioning, the plant underwent further refinements to optimize the performance of its turbines and the efficiency of the hot water distribution system. The integration of these components allowed ON Power to maintain a consistent supply of energy to Reykjavík, reinforcing the city's reliance on geothermal resources. The facility's design, which combines electricity generation with district heating, has served as a model for subsequent geothermal developments in Iceland. The period from 2006 to 2011 was marked by the successful establishment of the plant's operational protocols, ensuring that the 303 MW of electrical capacity and 200 MWth of thermal capacity were reliably delivered to the grid and the district heating network. This phase of development solidified Hellisheiði's role as a cornerstone of Iceland's energy infrastructure, supporting the country's transition toward a predominantly geothermal-powered economy.
What are the environmental innovations at Hellisheiði?
Hellisheiði Power Station has implemented significant environmental innovations to mitigate the ecological footprint of geothermal energy production, specifically targeting gas emissions and carbon sequestration. A primary challenge in geothermal operations is the release of hydrogen sulphide (H2S), a byproduct of the boiling process that can oxidize into sulphur dioxide, contributing to acid rain and local air quality issues. To address this, the facility introduced advanced reinjection systems designed to capture and return these gases to the reservoir. The 2014 implementation of enhanced hydrogen sulphide reinjection marked a critical step in reducing the plant's atmospheric emissions, ensuring that a higher percentage of the extracted H2S is returned to the Hengill geothermal field rather than being vented or burned off.
Carbon Capture and Mineralization
Beyond gas management, Hellisheiði serves as a global testbed for Direct Air Capture (DAC) technology through a partnership with Climeworks. This pilot facility represents one of the world’s largest DAC plants, designed to extract carbon dioxide directly from the ambient atmosphere. The captured CO2 is then combined with water to form carbonic acid, which is pumped into basaltic rock formations beneath the site. This process, known as carbon mineralization or the CarbFix method, accelerates the natural process of turning CO2 into solid stone. The mineralization occurs within the porous basalt layers of the Hengill range, effectively locking the carbon underground for thousands of years. This innovation demonstrates the potential for geothermal sites to transition from net-zero to net-negative carbon emitters.
Funding and Research
The integration of these advanced environmental technologies has been supported by significant research funding, including grants from the European Union’s Horizon 2020 program. These funds have enabled the scaling of the Climeworks pilot and the refinement of the H2S reinjection protocols. The collaboration between ON Power, Climeworks, and academic institutions has positioned Hellisheiði as a reference site for global geothermal sustainability, providing data on the efficiency of DAC in high-temperature geothermal environments and the long-term stability of mineralized carbon. These efforts align with Iceland’s broader energy strategy to leverage its unique geological advantages to combat climate change.
How is the resource managed?
The management of the geothermal resource at Hellisheiði has required active intervention to maintain steam pressure and temperature stability. Since 2013, operators observed a gradual decline in steam levels within the reservoir, prompting a strategic response to ensure long-term operational efficiency. To address this, a dedicated drilling program was initiated in 2016. This initiative aimed to tap into new veins of the Hengill geothermal system, thereby replenishing the steam supply and mitigating the effects of resource depletion observed in earlier production phases.
Drilling and Reservoir Adjustment
The 2016 drilling campaign represented a significant capital expenditure for ON Power. The program involved the exploration and exploitation of deeper sections of the Hengill reservoir, which lies approximately 11 km from the Nesjavellir Geothermal Power Station. By extending the wellfield, the plant aimed to access higher enthalpy zones, ensuring that the 303 MW electrical capacity could be sustained without excessive drawdown of the primary steam field. The operational adjustments included optimizing the injection rates of cooled brine back into the reservoir, a standard practice in geothermal management to maintain pressure equilibrium.
These measures were critical for the facility, which is the largest geothermal power station in Iceland and the eighth-largest globally. The integration of new wells allowed for a more balanced extraction profile, reducing the thermal stress on the original production wells. The costs associated with this drilling program were substantial, reflecting the high initial capital intensity of geothermal development. However, the investment was deemed necessary to secure the long-term viability of the plant's output for Reykjavík's district heating network, which relies on 200 MWth of hot water from the facility.
Operational Outcomes
Following the completion of the drilling program, the plant's operators monitored the reservoir's response closely. The introduction of new production wells helped stabilize steam pressure, allowing the plant to maintain its rated capacity. The strategic management of the Hengill resource demonstrates the dynamic nature of geothermal energy production, where continuous geological monitoring and infrastructure adaptation are required to sustain output. The success of the 2016 initiative ensured that Hellisheiði could continue to serve as a cornerstone of Iceland's renewable energy mix, supporting both electricity generation and district heating for the capital region.
Frequently asked questions
What is the primary function of the Hellisheiði Power Station?
Hellisheiði serves as Iceland's largest geothermal facility, providing essential energy to the capital region. It generates 303 megawatts of electricity and supplies 200 megawatts of thermal energy as hot water for Reykjavík.
How does Hellisheiði generate its energy?
The plant harnesses geothermal resources from beneath the Earth's surface to produce power. This process involves extracting heat and steam to drive turbines for electricity generation and to heat water for distribution.
What makes Hellisheiði notable for environmental innovation?
The station is recognized for its significant contributions to environmental sustainability, particularly through advanced carbon capture technologies. These innovations help reduce the carbon footprint associated with geothermal energy production.
How is the geothermal resource at Hellisheiði managed?
Efficient resource management is critical to maintaining the plant's output and longevity. Strategies are employed to monitor and regulate the extraction of heat and steam to ensure sustainable operations.
Why is the Hellisheiði Power Station considered important?
It plays a vital role in Iceland's energy infrastructure by supplying a substantial portion of Reykjavík's electricity and heating needs. Its scale and efficiency make it a cornerstone of the country's renewable energy landscape.
References
- Hellisheiði Power Station - Global Energy Monitor
- Hellisheiði Geothermal Power Plant - Orka (Official Operator)
- Carbon Capture and Storage at Hellisheiði - Carbfix Project
- Geothermal Energy - IRENA