Iceland Discovers "Clean" Geothermal Power Plant Not So Clean
Yes, Virginia, there really is no such thing as a free lunch....
Iceland officials are discovering that geothermal energy is not as clean as they expected.

In 2006, when the Hellisheidi geothermal power plant began operating, about 30 kilometers from central Reykjavik, city residents started noticing that they had to clean their silverware every three to four days instead of every three to four months because it was covered with black soot. Truck drivers who drove daily to sand mines in western Hellisheidi found the rubber in their vehicles' suspension and steering systems became hard and prone to breakage after one year instead of three to five years.

Then, in September 2008, people noticed that moss vegetation near the Hellisheidi plant was severely damaged.

Reykjavik Energy commissioned research and discovered strong indications that sulfur derived from hydrogen sulfide is the cause of the damage. Mercury was also found in high concentrations in some dead moss.
But...but...but geothermal is so earth-friendly! Mother Gaia makes it herself!
The damage stems from the steam produced at the plant. Most of this is water, but 0.4 percent of the steam contains gases of various kinds - 83 percent is carbon dioxide (CO2), 16 percent hydrogen sulphide (H2S), and the remainder other gases. Trace elements in the steam include sulphur, mercury, boron, arsenic and aluminium.
And none of this, I'm sure, would cause silver to tarnish or rubber to harden and crack. /sarc
The environmental impact assessment (EIA) reports assumed that because Hellisheidi is a windy, rainy place, most of the H2S would be transformed into sulphur and washed away into the soil instead of being carried elsewhere. Nevertheless, in 2006 and 2007 several measuring gauges were set up in the capital area to check the pollution levels.

The Hellisheidi plant was brought into operation in September 2006. Immediately, increased levels of H2S were seen in Reykjavik, especially when the wind blew from the east or south-east, from the plant to Reykjavik. Because of increasing concerns over H2S levels, more measuring devices are being set up around the city, and the Environment Ministry has requested the Environment Agency to find ways of reducing H2S levels overall.

The Environment Ministry is also working towards a new regulation on the release of H2S which will include maximum permissible discharge levels from geothermal plants. World Health Organisation (WHO) guidelines state that exposure to H2S should not exceed 150 micrograms per cubic metre, which Reykjavik has exceeded once so far.

Are levels of H2S poisonous to human health? At very high levels, yes, says Thorsteinn Johannsson, an air quality officer with the Environment Agency. "But the levels found in Reykjavik would not cause health problems. On the other hand, we know very little about the long-term effects of H2S on health. Iceland would be a good place to research this," he said in a recent radio interview.
I'm sure the Icelanders won't mind being guinea pigs for you, Mr. Johannsson.
Posted by: Barbara Skolaut 2009-05-27