| Title | Pilot Scale Geothermal Gas Separation, Hellisheiði Power Plant, Iceland |
|---|---|
| Authors | Ingvi GUNNARSSON, Bjarni Már JÚLÍUSSON, Edda Sif ARADÓTTIR, Bergur SIGFÚSSON and Magnús Þór ARNARSON |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Geothermal gas, separation, dissolution, re-injection, Hellisheiði Power Plant |
| Abstract | Reykjavik Energy has since the commissioning of Hellisheiði Power plant in 2006 put more effort into developing methods to lower geothermal gas emission from its geothermal power plants. The aim is to make the geothermal power production more environmentally friendly by lowering CO2 emissions and to decrease local atmospheric pollution caused by the foul smell and toxic and corrosive properties of H2S. The gas abatement method Reykjavík Energy is aiming towards is to dissolve the geothermal gases in effluent water from the power plant and re-inject them back into a geothermal reservoir. An essential part of developing a gas reinjection method is to separate the geothermal gases based on their solubility in water. Getting rid of the poorly soluble geothermal gases prior to reinjection greatly reduces the water needed to dissolve gases before injection. A pilot scale gas separation station was built next to Hellisheiði geothermal power plant. The goal of the pilot operation is to develop commercially feasible methods to separate geothermal gases prior to re-injection into the ground. Capacity of the pilot gas separation station is 1-2% of the total gas exhaust from the Hellisheiði power plant. Three kinds of technologies are under scrutiny in the station, a membrane system for H2 removal, a system comprised of adsorption and desorption towers which separates the soluble gases CO2 and H2S from the rest of the geothermal gases and a distillation column to separate CO2 and H2S. The flexible design and construction of the gas separation station provided opportunities to combine the systems or run them on their own. This pilot scale gas separation station provided gas for two gas reinjection projects Sulfix (re-injection and mineral sequestration of H2S into the high temperature reservoir) and CarbFix (re-injection and mineral sequestration of CO2 into a low temperature reservoir). Based on the successes of the pilot scale gas separation station a gas separation station is being build next to Hellisheiði power plant capable to dissolving around 15% of H2S from the power plant along with some CO2. This gas separation station will start operation in the spring of 2014 and subsequently large scale re-injection of geothermal gases starts. |