There are about 20 high temperature areas in Iceland. They are all situated on or near active volcanic and rift zones, in the centre of volcanic systems and they are defined as areas where geothermal temperature is 200°C at 1000 m depth. For the geothermal fluid to reach this temperature, the source of heat must come either from magma chamber or magma intrusion, where the magma heat can reach 1000-1200°C.

Geothermal powerplants on Iceland are built on that principle and near to these volcanic hotspots. There are nine geothermal plants in operation on Iceland with total output of 799 MWe. This output represents 26% of Iceland’s total electricity production. Therefore It is not suprising that nearly all of Iceland’s electricity (>99%) is generated from renewables (mainly hydroelectric dams and geothermal).

Hellisheiði Power station (Hengill area). Photo: Petr Kalina

Since 1990 hot water from the geothermal powerplants in Hengill area is piped to Reykjavik area through the pipeline made of steel insulated with rock wool. The temperature of the water from the power plants is about 85°C and the heat loss to Reyjavik is less than 2°C.

A bit of history of using geothermal energy on Iceland

Geothermal energy has been employed by Icelanders since the Viking Age, with initial uses including washing and bathing, however the first settlers were also afraid of geothermal energy outbursts to surface thinking that it is dangerous for health. Only later, it began to be used to heat homes, greenhouses, and swimming pools, as well as to keep streets and sidewalks free of snow and ice. Still the partial distrust of geothermal energy potential persisted.

From 1930´s Icelandic people were building heating and electricity generation systems based on imported fossil fuels, such as coal. Triggering point for geothermal energy usage was energy crisis in 1970´s when the national government  looked to address energy price inequities across the country.

A report commissioned in 1970 by the country’s National Energy Authority, recommended increased domestic production of geothermal power and hydroelectricity to stabilize energy prices and reduce the nation’s reliance on external energy resources. Within a few years, geothermal energy space in Iceland increased from 50% to 85%. Nowadays, 90% of houses in Iceland are heated with geothermal energy.

Carbfix

Trees and vegetation are not the only form of carbon drawdown from the atmosphere. Vast quantities of carbon are naturally stored in rocks.

Nesjavellir Carbfix site. Photo: Petr Kalina

Carbfix imitates and accelerates these natural processes, where carbon dioxide is dissolved in water and interacts with reactive rock formations, such as basalts, to form stable minerals providing a permanent and safe carbon sink. Thus, the carbon dioxide is transformed into rock, becoming a mineral called calcite.

The Carbfix process captures and permanently removes CO2. The technology provides a complete carbon capture and injection solution, where CO2 dissolved in water – a sparkling water of sorts – is injected into the subsurface where it reacts with favorable rock formations to form solid carbonate minerals via natural processes in about 2 years.

For the Carbfix technology to work, one needs to meet three requirements: favorable rocks, water, and a source of carbon dioxide. All 3 requirement are readily met on Iceland.

Source: carbfix.com

Carbonated water is acidic. The more carbon you can pack into water, the more acidic the fluid will become. Carbfix’s carbonated water reacts with rocks underground and releases available cations such as calcium, magnesium and iron into the water stream. Over time, these elements combine with the dissolved CO2 and form carbonates filling up the empty space (pores) within the rocks. The carbonates are stable for thousands of years and can thus be considered permanently stored. 

The timescale of this process initially surprised scientists. In the CarbFix pilot project, it was determined that at least 95% of the injected CO2 mineralizes within two years, much faster than previously thought.