
Hellisheiði & Nesjavellir (Iceland)
Demosite Showcase

Hellisheidi and Nesjavellir geothermal power plants are located on the Hengill volcanic system, SW Iceland. Both are hosted on a high temperature basaltic reservoir. Currently about 1/3rd of CO2 and 2/3d of H2S are captured and injected at Hellisheidi. No capture and injection is taking place at Nesjavellir yet. GECO aims to improve efficiency of pre-existing gas capture and injection infrastructure at Hellisheidi, turn captured CO2 into value stream at Hellisheidi, and commence pilot scale capture and injection at Nesjavellir.

Geology, Reservoir Properties
The Hengill volcanic system in SW-Iceland includes a 60-70 km long NE-SW trending fissure swarm and a central volcano. Within the system two high-temperature geothermal fields have been exploited for electric and thermal power production at Hellisheidi on the southern side and Nesjavellir on the northern flank.
GECO Technology
Reservoir modeling
Injection
Monitoring
Gas Purification
History of the site
Hellisheidi geothermal power plant was commissioned in 2006. Since 2007 Reykjavík Energy (OR) has been developing new solutions in reducing gas emissions at Hellisheidi through the CarbFix project. Capture of CO2 and H2S is carried out via a scrubbing unit that only uses water and electricity. Captured gases are dissolved in water and injected back into the geothermal reservoir where they mineralize as monitoring has demonstrated. Pilot scale capture and injection commenced in 2011 and was scaled up in 2014. Currently, about 15,000 tonnes of CO2 and 8,000 tonnes of H2S are captured and injected annually into the basaltic rock at Hellisheidi.
Nesjavellir power plant was commissioned in 1990. Like Hellisheidi, it is a co-generative, flash-unit power plant producing electricity and hot water from a high temperature basaltic reservoir. Capture and injection is not taking place at Nesjavellir yet.


Timeline
2018
Start of GECO project
2018
2021
Commissioning of Nesjavellir capture plant
2021
2022
Pilot injections in Nesjavellir
2022
