They all needed to defend the land as if it were a sick child, Mr. Michele said.

“I’m not a geologist, I have another job,” he said shortly before pricking one of his fingers, garlanded in Renaissance rings, on an exposed nail on the back of the chair. “My job is to preserve beauty. And hasn’t beauty a value?”

The opponents of the plant have tried to prove it will be an environmental menace. They also say the approval process was rigged.

They have seized on the fact that Franco Barberi, a volcanologist and former government minister who is a member of a state commission that approved the project, is married to a woman who is also a volcanologist and was one of the experts who helped determine the area was seismically safe for digging.

Mr. Barberi denied any wrongdoing. He said that he recused himself from the decision, that the process was legitimate, and that his wife did only preliminary examinations before the project even began.

“My wife and I have a clear conscience,” he said.

The company building the plant says it uses an environmentally friendly system with zero carbon emissions to produce electricity. It would help, not harm, the environment and never trigger an earthquake, it says.

“The well-off want everything to remain the way it is so they can remain the ones who are well off,” Diego Righini, the company’s general manager, said in his offices near the Spanish Steps in Rome. He portrayed the resistance as “Not in my backyard” elites.