The Algerian blast was caused by a leak that allowed gas to flow into the boilers through an air intake.

That won't happen again, Frederick said.

"One of the things that changed worldwide after that was gas detection at all air intakes of fuel-burning equipment," he said. "If there were a cloud, the gas detection would sense that and shut it down."

Frederick said Cove Point has duplicates of each safety system, just in case.

"If all that failed — I'm telling you it won't — but if all that failed, an issue would be contained on the site," he said.

Though chilling gas to a liquid is more complex than reversing the process, Frederick said exporting is no more inherently dangerous than importing.

James Fay, a professor emeritus of mechanical engineering at the Massachusetts Institute of Technology, disagreed. He said an LNG export facility has the potential to be much more dangerous. Propane gas is generally used as a refrigerant in the liquefaction process, he said, and propane can catch fire.

"This is not a simple little addition," Fay said of Cove Point. "An export terminal is entirely different from an import terminal."

Cove Point's existing storage tanks, including three added by Dominion after it bought the facility in 2002, would be used for the export business. That's another point of contention, because the tanks use single-wall containment, without the extra layer of protection built into other models.

It alarmed neighbor Dale Allison to think the company is using what he called "the least-safe tank."

Frederick said each tank is set in a pit that's designed to contain the maximum amount of liquid in a spill — 110 percent of the tank's capacity. The design would prevent vapor clouds from traveling off site, he said, and any fire would stay put as well.

"The bottom line is, we modeled the situation so what you just described doesn't happen," he said.

Nevertheless, opponents aren't satisfied.

Tidwell, with the climate action network, criticized the FERC's decision to take the less extensive of its two review options.

"They're fast-tracking this," said Tidwell, whose group is organizing a Baltimore rally against the expansion next month. "Is this happening so fast that there's some major safety risk that has not been thought through?"

The environmental assessment that FERC staffers are working on will consider a variety of issues, safety included. But such assessments don't examine as many issues as a full environmental impact statement, and offer people less time — and no public hearings — to comment on it.

Dominion executives said the environmental assessment is no quick or slapdash effort. The company already has filed 21,000 pages of documents in the FERC case that started in 2012, they said.

"The idea that it's not thorough is just not true," Frederick said.

June Sevilla, a chemical engineer who lives near Cove Point, worries about a potential fault near the facility.

There likely is a fault in the area, said Peter Vogt, a semiretired marine geophysicist who lives about 10 miles from Cove Point. There's evidence of one in a valley nearby, but more work would need to be done to confirm that, as well as how far it reaches and how long it's been inactive, he said.

Vogt, who dislikes the tax break but is otherwise open-minded about the Cove Point proposal, thinks the possible fault leaves a nagging question and that more research should be done.

Dominion's Frederick said the design already takes earthquakes into account, along with hurricanes and tornadoes. And the company said it thoroughly considered seismic threats along with the FERC and the Maryland Department of Natural Resources.

Dominion, which negotiated exporting contracts for the facility with companies in India and Japan, is hoping for a decision from the FERC in the near future. The firm is ready to start construction this spring, if approved, and begin exporting in 2017 — adding about 75 jobs to the 100 there now.

The county's coffers would get a boost, though partially muted by the tax break. Dominion would pay $40 million more in annual property taxes for five years, increasing the rural Calvert County's total property tax revenue by more than 25 percent. That would be followed by a 42 percent tax break for nine years.

Cove Point's import contracts begin expiring the year Dominion hopes to start exporting and will all be gone by 2023. Unless the natural gas market takes another dramatic turn, the company doubts it will import more.

"There's no economic sense to have somebody import gas to the United States at the same time somebody's exporting gas from the United States," Wade said.

jhopkins@baltsun.com

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