With the geothermal plants situated at Hengill - an active volcanic area - emissions of H2S (hydrogen sulfide) and CO2 (carbon dioxide) are released naturally from the area. Harnessing the geothermal resources has increased the concentration levels of those emissions with the expansion of the Hellisheiði Plant in recent years. ON Power has worked to reduce those emissions by injecting H2S and CO2 back into the bedrock. The process dissolves H2S in condensate water and injects it back into the high-temperature geothermal reservoir. Once injected, water-rock reactions taking place in the high-temperature geothermal reservoir will mineralize the H2S. This method continues to be tested at industrial scale at the Hellisheiði Power Plant since early 2014.