Italy pushing for geothermal renaissance

Alexander Richter 5 Mar 2009

Scientists in Italy are hoping to once again put their country at the forefront of geothermal energy research. Later this year they will drill a well 4 km deep into Campi Flegrei, a geological formation lying just to the west of Naples.

Published by the Environmental Research Web, it seems like Italy is trying to revitalize geothermal development in the country.

“Scientists in Italy are hoping to once again put their country at the forefront of geothermal energy research, by extracting power from one of the Earth’s most explosive volcanic areas. Later this year they will drill a well 4 km deep into Campi Flegrei, a geological formation lying just to the west of Naples known as a caldera, which formed from the collapse of several volcanoes over thousands of years.”

Based on the article there seems to be a refound believe in the need for geothermal development in the country, which has long be a leading nation with about 800 MW installed geothermal electricity generation capacity. The first geothermal power plant was installed at Larderello in Tuscany in 1911.

“Central to this expansion, says iuseppe De Natale, a geophysicist at the Vesuvian Observatory in Naples, will be exploiting Campi Flegrei. He points out that this is an ideal site for geothermal energy production because its subsurface temperature increases rapidly with depth and because it contains natural reservoirs, which means that the water that is used to carry away the heat does not have to be pumped in from outside. He believes that, given the political will, the fraction of the country’s electricity generated by geothermal could rise five-fold to as much as 10% within the next 10 years.

As co-ordinator of the Campi Flegrei Deep Drilling Project, De Natale is leading an international collaboration of scientists to bore a well 4 km deep in the area by the end of the year. At this depth the water in the reservoirs should be at about 400°C and therefore be supercritical, with liquid and vapour existing simultaneously. In this state, water reaches the surface as high-pressure steam, enabling it to transfer power to electrical turbines, with each individual supercritical well providing up to 50MW.

However, power plants using supercritical water will take some time to develop. They are expensive because they require deep wells and are technically demanding because of the high pressures involved. They also have an impact on the environment, due to the various subterranean gases, including carbon dioxide, emitted directly into the atmosphere when the geothermal water vapour is passed through the turbines.

De Natale says that he and his colleagues will use the results of a test on supercritical geothermal energy to be carried out shortly in Iceland, a heavy user of geothermal energy. In the meantime, the team is pursuing a less powerful but more environmentally friendly technology known as “binary fluid plants”. This involves pumping geothermal water at 100- 180°C from just a few hundred metres below the surface and transferring the heat from the water to a secondary fluid with a low boiling point that vaporizes and drives a turbine, before injecting the water back into the reservoir to complete a closed circuit.

“Once we have shown the people and politicians the potential of geothermal energy in this area, I believe it will be easier to persuade them to move to the more powerful supercritical technology,” says De Natale.”

Source: Environmental Research Web (physicsworld)