A Swiss court on Monday acquitted a geologist accused of causing earthquakes while drilling deep into the ground in a pioneering attempt to produce clean energy.
The Basel criminal court said it acquitted Markus Haering because he had not deliberately damaged properties or acted carelessly on the heat mining project, which aimed to be the first to generate power commercially by boiling water on rocks three miles underground.
The project was put on hold in 2006 after the drilling accidentally triggered a series of tremors, including one of 3.4 magnitude, rattling residents of the northwest city of Basel.
Project leader Geopower Basel has already paid around 9 million Swiss francs ($9 million) in compensation for cracked walls and other damage on properties near the experiment. The project was permanently shut down earlier this month after a risk analysis concluded that more quakes could follow if the drilling continued.
Haering, who rejected the allegations though he acknowledged his surprise at the strength of the most powerful temblor, said he was relieved by the verdict but disappointed by the project's failure.
"The tremors we caused are a strong setback for deep geothermal energy," Haering said in a statement.
"We don't get innovation for free. We have to work it out," he said.
Basel prosecutor Thomas Hug indicated that he was unlikely to appeal the ruling.
Other attempts in Switzerland to tap the heat of the Earth's bedrock are continuing in zones that are less earthquake-prone. Engineers in Zurich started preliminary drilling last month to see if the area there was suitable.
St. Gallen in eastern Switzerland plans to start drilling on its own geothermal project next year.