Geothermal company fails to meet H2S limit

    An Icelandic geothermal power producer has been given two extra years to comply with an air quality standard for hydrogen sulphide (H2S) that was meant to apply from July.

    The original standard, set four years ago, allowed average levels of H2S over 24 hours to exceed 50 micrograms per cubic metre in air measured near the plant five times a year until 1 July 2014. After that, they were never meant to exceed this level. The limit was set because of uncertainty over the long-term health effects of H2S.

    Reykjavik Energy (RE) has two plants near Reykjavik but most of the problem is associated with the large Hellisheidi plant built 30 kilometres east of the city in 2006.

    The firm realised some time ago it was unlikely to meet the standard and originally asked for a five-year extension to allow it to investigate options for lowering emissions.

    It hopes it will be able to meet the standard using a technique known as Sulfix in which the H2S is mixed with waste water from the plant and pumped back down a kilometre into the geothermal reservoir. Initially 15-20% of H2S will be removed in this way. If the technique works, RE will double the amount captured.

    It says Sulfix is more environmentally sound than other techniques used in the oil and gas industry. “There, the problem is shifted rather than solved. Sulfix takes the H2S back to where it originated,” says Holmfridur Sigurdardottir from the firm.
    Iceland has five other geothermal plants but H2S emissions are not such a problem at these. In other countries, H2S is emitted principally from pulp and paper mills, oil refineries, tanneries and some industrial processes. Italy also has geothermal power plants but the bedrock there is different from that in Iceland.

Excerpted from ENDS Europe DAILY