Frequently Asked Questions

FAQs Masthead

Learn About Liquefied Natural Gas & LNG Storage

Get information about the Access Northeast project and about liquified natural gas usage, storage and regulations.

Liquefied Natural Gas

What is Liquefied Natural Gas (LNG)?

“LNG” is liquefied natural gas—natural gas cooled to a temperature of about -260 degrees Fahrenheit at which it condenses into a liquid form. Liquefying natural gas reduces its volume by 1/600th (in other words, 600 cubic feet of natural gas is reduced to 1 cubic foot of LNG, making it more practical to store and transport. LNG is stored cold in insulated containers at near atmospheric pressure.

How is LNG used?

In New England, nearly 50% of the electric generation supply comes from cleaner-burning, natural gas-fueled power plants. During the coldest winter days, as much as 40% of New England’s natural gas supply comes from LNG. Liquefying natural gas reduces its volume by more than 600 times, making it easier to transport and for long-term storage so it can be vaporized and made available to create electricity for customers during peak demand periods, when the supply of natural gas might otherwise be limited or unavailable.

Is LNG safe?

LNG is not stored under pressure and is not explosive. The LNG industry’s highest priority has been safety and security, which is reflected in the industry’s enviable safety record. There have been no safety incidents during the 40 + years in which the existing Acushnet LNG facility has been in operation.

Why did you pick this location for the LNG facility?

Eversource Energy and its predecessor companies have operated a LNG facility in Acushnet for more than 40 years on a safe and reliable basis. The new facility will be only 3 miles from the Algonquin pipeline. This will be a minimally invasive project with significant benefits for the local communities and the region.

Do the developers of the Access Northeast Project have experience owning and operating a market area storage LNG facility?

Eversource Energy and National Grid, two of the three lead developers of the Access Northeast project, are long-time LNG operators. Eversource operates LNG facilities in Hopkinton and Acushnet, Massachusetts, and in Waterbury, Connecticut. National Grid operates multiple LNG facilities throughout the northeast, including the iconic rainbow tank alongside the Southeast Expressway in Boston. National Grid has more than 40 years’ experience in the liquefaction process and transporting LNG, and currently operates liquefaction facilities in downstate New York.

The existing market area storage facilities in Acushnet are located on a 15-acre parcel within a 250-acre tract of property owned by Eversource. The Acushnet LNG facilities have operated safely and reliably at this site for more than 40 years. The Acushnet LNG facilities encompass two LNG storage tanks with total storage capacity of 0.5 Bcf (billion cubic feet). The new facility will be constructed on an adjacent parcel within the larger Tract. The interstate pipeline owned and operated by Algonquin Gas Transmission runs within three miles of the Acushnet LNG facilities.

How is LNG stored?

LNG is stored at atmospheric pressure in double-walled, insulated tanks that act much like a thermos. The inner tank contains the LNG, while the outer tank contains the insulation and also acts as secondary containment in the unlikely event of a leak.

What is an LNG "peak-shaving" facility?

LNG peak-shaving facilities are used to store LNG to meet peak consumption during the winter. Each peak-shaving facility has a vaporization unit that converts LNG into natural gas and some have a liquefaction unit, which converts natural gas into LNG. Of the approximate 113 active LNG facilities in the United States, 93 are peak-shaving facilities.

How are LNG tanks constructed?

LNG tanks are designed and built using double-walls, with extremely efficient insulation between the walls. The inner tank is made of a special nickel steel alloy that can resist the cold temperatures associated with direct exposure to LNG. The outer tank will be a thick-walled, steel lined, pre-stressed steel reinforced concrete tank designed to contain the LNG in the extremely unlikely event of a leak in the inner tank. The tanks are built to withstand high winds, floods and earthquakes.

What if there is a spill or a release? What would happen?

There are numerous layers of safety and security systems in place to prevent such incidents. There are also monitoring systems in place to quickly detect a leak and trigger the safety systems. Storage tanks are built with multiple layers of containment.

LNG is not explosive, toxic, nor carcinogenic. In the event of a release of LNG from the inner storage tank, that leak will be contained by the outer tank. In the highly unlikely event of an additional leak in the outer tank, LNG will vaporize, meaning that the liquid will warm up and change back into a gas. This gas would quickly dissipate as it warms up and becomes lighter than air, leaving no environmental trace.

Is LNG environmentally friendly?

LNG is widely recognized as an environmentally friendly fuel source. Unlike some other fossil fuels, natural gas is non-carcinogenic and non-toxic. When liquefied, impurities such as sulfur, carbon dioxide, mercury and water are removed from natural gas and safely disposed of. This creates a product that, when re-vaporized and transported to customers, is clean burning and safe for the environment. Compared to the average air emissions from coal-fired generation, natural gas produces half as much carbon dioxide, less than a third as much nitrogen oxides, and one percent as much sulfur oxides at the power plant.

How are LNG facilities regulated?

The siting, design, construction and operation of LNG facilities are regulated by many government agencies. For Access Northeast, the Federal Energy Regulatory Commission (FERC) will be the lead federal agency in reviewing the project (including the proposed LNG facility) under Section 7 (c) of the federal Natural Gas Act (NGA). Other federal and state agencies will participate in the FERC process as consulting agencies and/or will administer other permitting processes. The following are a few of the agencies that regulate LNG facilities:

The Federal Energy Regulatory Commission (FERC) regulates such things as gas transportation rates, pipeline capacity, pipeline siting and natural gas quality requirements. For LNG facilities, FERC will perform a design review and ensure the safety and reliability of LNG facilities.

The U.S. Department of Transportation (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) and their state and local agents provide regulation for the safe transportation of natural gas through pipelines. For LNG facilities, DOT PHMSA also maintains the federal siting and design standards for LNG facilities.

The U.S. Occupational Safety and Health Administration (OSHA) provides regulation for the safe working place for our employees.

Are there restrictions on the proximity of LNG facilities to residential areas?

Yes. Applicable regulations and safety codes require that LNG containers and transfer systems be located far enough away from residential areas to protect residents and property in case of an accident. The distance depends on various factors, including storage tank design, site plan configuration, and natural features (e.g., topography). “Exclusion zones” are areas around LNG facilities where public activities are prohibited or restricted—and the facility operator must demonstrate control over these zones. In the remote event of an LNG spill or fire, these exclusion zones are intended to help protect the public and their property from damage.

How are LNG facilities secured?

Safety and security have always been extremely important for LNG operators and regulators. General security and operating procedures that prevent security breaches and manage safety risks include: tightly controlled access to LNG facilities; security zones around the facility; redundant security fences and alarms; separation distances around facilities and equipment; 24-hour surveillance; constant communication; coordination with local, state, and federal agencies; and frequent inspections and safety drills.

Will LNG explode?

LNG is not explosive or flammable in its liquid state and LNG vapors in an open environment cannot explode. To create an explosion, LNG vapors would have to be spilled, evaporate to create natural gas, be mixed in an even tighter ratio with air, be in an enclosed space (such as a building) and have an ignition source – circumstances, which are nearly impossible to find at an LNG facility.

Why do some people worry about LNG's potential hazards?

LNG storage facilities are not as familiar to most people as power plants, gas stations and other energy infrastructure. They hold a lot of stored energy and people often assume, incorrectly, that this creates an explosion hazard. LNG, in liquid, is not flammable and cannot explode. The bottom line is that LNG, based on its safety record and characteristics, ranks as one of the safest and least environmentally hazardous energy sources.

How is LNG vaporized and is this conversion safe?

LNG is converted back into natural gas by simply warming it up. This is accomplished using vaporization systems that typically use gas-fired heaters to warm a Heat Transfer Fluid (HTF) through which LNG is piped. The LNG warms due to its exposure to the heated fluid and is effectively vaporized. Vaporization allows stored LNG to be re-injected into a natural gas pipeline to be distributed to homes, power plants generating electricity, and local businesses. The vaporization process is performed using advanced technologies with proven safety records.

How is natural gas liquefied and is this conversion safe?

Natural gas is converted into a liquid state through a process of compression, cooling, and expansion. The process requires the use of a refrigerant. The Access Northeast project will utilize nitrogen, which is nonflammable and will be used as a single component refrigerant. No flammable refrigerants (such as ethane, ethylene, or propane) will be used in the liquefaction process.