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Geothermal energy

Up-scaling Geothermal Operations: Hellisheiði & Nesjavellir

The current capture plant at the Hellisheiði geothermal power plant is a 13 meters tall scrubbing tower, which dissolves 15,000 tons of CO2 and 8,000 tons of H2S in water every year. This is then injected into the basaltic bedrock where it forms solid carbonate and sulfide minerals.

Carbfix operations at Hellisheiði have considerable scale up potential, providing significant impact for emission reduction within Iceland’s geothermal sector. Carbfix has recently received a grant from the EU Innovation Fund to commission a full-scale CO2 capture and mineral storage facility at Hellisheiði through Project Silverstone. A new, CO2-optimized capture plant will increase capture efficiency to 95% of the total CO2 emissions, expected to reduce emissions by 500,000 tons of CO2 over a 20-year equipment lifetime.

There are additional plans underway at Nesjavellir geothermal power plant to start a new CO2 capture and storage site. Pilot scale injections will start in 2022 leveraging a new mobile pilot plant that is in construction and will increase efficiency of CO2 capture. This plant will have an annual capture capacity of 1000 tons CO2. The pilot phase will be followed by full-scale CO2 capture and storage before 2030.

Both Hellisheidi and Nesjavellir Carbfix sites are Geothermal Emission Control (GECO) EU funded research projects.

In the Icelandic government's Climate Action Plan, the Carbfix technology is mentioned as a necessary instrument to reach Iceland´s goals of a 55% reduction in greenhouse gas emissions by 2030.

Carbfix and the GECO Project

The Geothermal Emission Control (GECO) project aims to make net-zero geothermal energy production standardized through the utilization of Carbfix’s carbon capture and mineralisation storage technology. Funded by the European Union’s Horizon 2020 research and innovation programme, the GECO project aims to apply the Carbfix method to four demonstration sites across Europe:

(1) Basaltic reservoir in Nesjavellir, Iceland,

(2) Basaltic reservoir in Hveragerði, Iceland, substituting for Castelnuovo, Italy

(3) Volcano-clastic reservoir in Kızıldere, Turkey

(4) Sedimentary reservoir in Bochum MULE, Germany.

GECO will implement lessons learnt at the first Carbfix demonstration site (Hellisheiði) to the four new field sites, where emissions will be captured for reuse or mineralisation storage.

Subsequent monitoring of carbon and sulfur mineralisation reactions occurring at the four GECO field sites will enable future predictions on the chemical behaviour of a variety of geothermal systems utilising the Carbfix method. The developed monitoring tools will decrease the cost and risk associated with geothermal energy projects in the future.

The GECO project is led by a consortium of experienced industry members and coordinated by Carbfix-Reykjavík Energy (OR). There are a total of 18 industrial partners spanning Europe and the Middle East. For more information on the consortium partners see here.

Global applications

There is vast potential to apply Carbfix’s CO2 capture and mineral storage to the global geothermal sector. Worldwide geothermal emission rates of CO2 and H2S greenhouse gases have been coupled to sequestration capacities (net CO2 and H2S drawdown) for annual emissions of suitable countries, generalised by appropriate rock type and associated geothermal systems. Marieni et al´s. (2018) study demonstrated that the Carbfix method may be applied to silicic rocks, such as dacitic and rhyolitic glass, in addition to the already proven use of Icelandic basalt. Significant potential has thus been identified in the following countries: USA, Mexico, Nicaragua, El Salvador, Costa Rica, Italy, Japan, the Philippines, New Zealand, Indonesia, and Kenya. It is notable that the sequestration capacities calculated are based on experimental conditions. Potential application of the Carbfix technology outside of Iceland is already underway with the development of the GECO project’s demonstration sites (see above).