The proposed construction of a new liquefied natural gas terminal in Baltimore Harbor and the proposed expansion of an existing terminal near Calvert Cliffs in Southern Maryland have ignited a fiery debate over the risks that such facilities pose to people and the environment.

AES Corp. has asked federal regulators for permission to convert the former Sparrows Point Shipyard in Dundalk into to a new LNG terminal. In addition, Dominion Resources has asked regulators for permission to expand the existing the Cove Point LNG plant to include two new storage tanks and to expand pipelines in Maryland and Pennsylvania.

The two projects are among dozens of proposals nationally to expand or build new LNG plants to meet the rising demand for natural gas.

On one side are energy companies who note that the very low risk of a spill or terrorist attack on tankers or terminals is outweighed by the need to keep natural gas prices low.

They say the industry has a 40-year track record of success and is heavily regulated. They also like to note that burning natural gas is a lot cleaner for the air —and ultimately better for the Bay—than burning coal or oil. And, new LNG plants create jobs—the $400 million LNG terminal proposed for Sparrows Point would create about 50 permanent jobs, according to company officials.

On the other side are community activists who say that the industry’s track record is not as good as advocates claim and worry that an accident or terrorist attack could result in a fire that would devastate neighborhoods and the environment. They also worry about the environmental impacts of building and expanding terminals.

Neither side disputes that demand for natural gas is growing in the United States.

Energy experts long ago found ways to cool natural gas so that it could be shipped as a liquid in tankers. A single tanker can carry enough LNG to supply the daily energy needs of 10 million homes.

Until recently, the low cost of natural gas produced in the United States had made the import of LNG economically unattractive.

But domestic demand for natural has grown dramatically in recent years as energy companies have used more natural gas to generate electricity—and less coal, which contributes to air and, ultimately, water pollution. “The nation has chosen to generate a lot of its electricity with natural gas because we want cleaner air,” said Dominion Resources spokesman Dan Donovan.

AES did not return calls seeking comment.

Experts now predict that LNG imports—which account for about 1 percent of U.S. natural gas consumption—could reach 20 percent by 2020.

That expected spike in demand has, in turn, resulted in a sudden surge in LNG plant construction and expansion proposals across the nation—and re-ignited long-simmering debates about the safety of LNG terminals and tankers.

Spilling the frozen stew into the Bay or Baltimore Harbor would certainly kill nearby aquatic life. And, expanding Cove Point would impact thousands of acres of wetlands, forest and farmland as well as many local creeks.

But, the most serious threat posed by LNG is not a spill or sudden explosion but what experts call a “pool fire.”

The contents of an LNG tanker are not shipped or stored under pressure—a common misperception, experts say—but are super-cooled to take up less space.

If LNG spills into the Bay or Baltimore Harbor. methane—an invisible gas—will begin to mix with the air, creating a potentially combustible brew, according to experts. Any ignition source—from a spark to a cigarette—would ignite the gas and air mixture above the spill and the resulting “pool fire” would burn until the all of the available LNG is consumed.

The intense “pool fire” would burn far more rapidly and hotly than oil or gasoline fires and could not be extinguished.

The intense heat of the “pool fire” could impact people and property up to 1,200 feet away, according to experts. The vapors caused by LNG are not toxic, although some experts warn that such a cloud could cause asphyxiation by displacing the air people breath.

An important consideration, experts say, is that methane will not ignite unless the mixture of gas and air is just right. And, if there is a fire, the fire will burn toward the source of the LNG, which is the tanker.

A spill from LNG tanks on land would be captured by dikes that surround LNG facilities and would be easier to contain, experts say.

LNG has been shipped by tanker for more than 40 years without a serious accident at sea or in port. Although some of the double-hulled tankers used to transport LNG have experienced groundings or collisions, none have resulted in a major spill. A recent federal study of the Cove Point expansion cited just eight significant incidents out of 33,000 voyages at sea.

But, the safety record of LNG terminals is less rosy, experts say. There are approximately 40 LNG terminals worldwide—including five in the United States.

Since 1944, about 13 serious accidents related to LNG have occurred at these facilities—including a 1979 accident at Cove Point that caused the death of a facility worker. More recently, a fire at an LNG facility in 2004 in Algeria killed about 30 workers.

Not surprisingly, the attacks on the World Trade Center and the Pentagon have heightened fears about LNG terminals, tankers and plants.

Citing the threat of terrorist attacks, Maryland State Sen. Norman Stone, D-Baltimore County, introduced bills that would tighten the regulation of LNG facilities and would prohibit new construction within two miles of a residence—which would have effectively blocked the Sparrow Point proposal.

Last month, Stone and Baltimore County’s legislative delegation settled for a bill creating a task force studying the issue. But, Stone remains undeterred, and pledged to introduce a bill that would ban LNG plants and oil refineries from being built within five miles of a residential area.

“In this post 9/11 world, it is impossible to talk about an LNG facility without considering a potential terrorist attack,” said Baltimore County Executive Jim Smith, who also opposes the LNG plant in Baltimore Harbor. “To bring almost daily shipments of liquefied natural gas up the Chesapeake Bay, under the Bay Bridge, into one of the busiest ports in the United States and into a major population center is just not reasonable and should not happen.”

Some opponents fear that tankers filled with the super-cooled gas would be an easy target for terrorists. The number of tankers that would dock at Cove Point—which is just a few miles from another potential target, Calvert Cliffs Nuclear Power Plant—would more than double if Cove Point were expanded.

Tankers filled with LNG must stop at the mouth of Chesapeake to wait for an escort by the Coast Guard. Once the tanker reaches the terminal, the super-cooled liquid is pumped into one of two pipes located about a mile away from the shoreline. The tankers and their crew are inspected when they leave port—primarily from the Caribbean island of Trinidad—and when they reach the mouth of the Bay.

But, Dominion’s Donovan said that a terrorist attack would be unlikely to succeed for a variety of reasons. Because the tankers have two hulls and other security features, a large boat would need to ram the tanker to cause a spill—and a large boat would be slow-moving and easy to intercept, he said. What’s more, the tanker would be more than a mile from shore.

“It would be a catastrophe for Dominion,” he said, but would not impact communities located a few miles away. “People think LNG is new, but it’s not,” Donovan said. “People drive past LNG tanks every day and never know it.” But, he said, people will “seize on the safety angle” when “they don’t want something in their backyard.”

Some opponents who have the Cove Point plant “in their backyard” wonder whether new pipelines that would be part of the Cove Point project are consistent with the needs of Calvert County. New pipelines would be buried under farms and creeks—and the 100-foot-wide strip of land above the pipelines would be maintained to prevent reforestation.

“My family’s farm is in the cross hairs,” said Brian Ferguson, a Saint Leonard farmer who opposes the Cove Point expansion and unsuccessfully refused to let Dominion surveyors on his land. “Our mixed variety of forests, undulating fields, and diverse wetlands” buffer Saint Leonard Creek, a naturally deep tributary to the Bay that could be impacted by the Cover Point project. “This is a truly unique environment and one that is inexplicably in danger of being altered for eternity.”

“There is literally going to be a 47-mile stripe through the watershed of Saint Leonard Creek,” said Ferguson, a corn and soybean farmer who has complied with regulations designed to protect the Bay and has accepted covenants that restrict development on his land. “We agree to these restrictions because farmers understand the need to protect our natural resources.” When a “company with deep pockets” can ignore those restrictions, “it’s a slap in the face,” he said.

Senator Stone and local officials and citizen groups gained a powerful and unexpected ally when Washington Gas recently complained that gas being delivered from Cove Point could damage pipe fittings and increase gas leaks.

The gas company urged federal regulators to oppose the expansion of Cove Point until the network of pipes that deliver gas to the region can be upgraded to handle imported natural gas. Washington Gas claims that imported gas has certain properties that are drying the rubber seals that link sections of pipe—a claim that Dominion Resources has rejected. They point to maintenance problems that caused the joints and seals to weaken.