Oil and Natural Gas - Energy Policy Analysis: A Conceptual Framework - page 91

In summary, clearing and earth-moving activities associated with construction of well pads and
roads, and human activity involved with oil and gas production create the most significant impacts
to animals. Many effects upon wildlife are indirect; for example, a loss of vegetation may result
in a loss of forage for animals, or a change in water quality may result in a change in fish popula-
tions. Other impacts would be direct; continued disturbance could result in complete abandonment
of disturbed areas by some wildlife species (MDFWP 1983; USDOI 1981a). Special care must
be taken to survey each location to identify any endangered species present, because they may
require special treatment to ensure they are not harmed by oil and gas development activities and
that any unavoidable impacts are successfully mitigated.
Liquefied Natural Gas
Cooling natural gas to about -260°F at normal pressure results in condensation of the gas into
liquid form, known as liquefied natural gas (LNG). LNG is useful for transportation of natural
gas, since LNG takes up about one six-hundredth the volume of gaseous natural gas (Natural
Gas Supply Association 2010). Oceangoing tankers transport large amounts of LNG from distant
natural gas fields. They are equipped with up to five LNG cargo tanks housed inside a double-
walled hull. Each cargo tank can store several thousand cubic feet of LNG. These ships are up to
1,000 feet long and, when fully loaded, require a minimum water depth of forty feet, deeper than
many U.S. harbors. Docking facilities, which are normally designed to accommodate the sizes
of anticipated LNG tankers, may consist of a pier about 1,800 feet long and 30 feet wide with
moorings and off-loading facilities (California Energy Commission 2003). Construction of such
facilities involves substantial modification of onshore and marine environments.
In most respects, an LNG docking facility would be similar in size to those that currently handle
supertankers delivering crude oil to deepwater ports. One difference is that an LNG tanker has a
much higher profile (125 feet). Therefore, when considering the placement of docking facilities,
facility designers must account for the effect of prevailing winds on the maneuverability of such
ships. Despite peak flow rates of about 12,000 cubic meters per hour, unloading times for a full-sized
LNG tanker average twelve to fifteen hours. While unloading their cargoes, LNG tankers could
be subject to substantial tidal and wave forces that might jeopardize the integrity of the ship-to-
shore interface. Consequently, LNG ports and jetties must have built-in safety features to prevent
releases of LNG during ship-to-shore transfers (California Energy Commission 2003, 2-3).
A shore-based LNG terminal—consisting of a docking facility, LNG storage tanks, LNG va-
porization equipment, and vapor-handling systems—occupies twenty-five to forty acres of land,
with associated facilities, such as roads, electric transmission lines, and gas and water lines that
would also be needed. These acreages represent considerable loss of habitat for shorebirds and
marine mammals. Currently, the United States has LNG receiving and regasification terminals in
Massachusetts, Maryland, Georgia, Louisiana, Texas, and Puerto Rico (California Energy Com-
mission 2003).
Such facilities may be operated without incident, but the consequences of a major LNG spill
could be catastrophic. When cold LNG comes in contact with warmer air, it becomes a visible
vapor cloud. As it warms, the vapor cloud becomes lighter than air and rises. When LNG vapor
mixes with air, it is flammable if the mixture contains between 5 and 15 percent natural gas. If
there is less than 5 percent natural gas in the air, there is not enough natural gas to burn. If there
is more than 15 percent natural gas, there is too much gas in the air and not enough oxygen for it
to burn (Natural Gas Supply Association 2010).
When enough LNG is spilled on water at a fast rate, heat is transferred from the water, caus-