Hunter & Hunter Trucking shows their commitment to lower harmful diesel emissions through the deployment of “ DUAL FUEL” LNG (liquefied natural gas)- powered trucks. Through this bold and strategic move, Hunter & Hunter Trucking not only helps the environment but, also sets an example for other carriers to follow. Harris Ranch of central California has been very instrumental in instructing us in operating a “DUAL FUEL” fleet; their help has been crucial to our success, from fueling (Harris Ranch sells LNG at their facility) to general information.

Hunter & Hunter Trucking has had “DUAL FUEL” trucks in operation for over 2 years with NO safety- related issues, Our trucks have traveled in excess of 2 million miles.

Drivers’ positive comments about the increase in performance and the seamless transition from diesel-powered trucks to LNG power are testament to the success of the program.

This is a first step for the transportation industry to do its part to remove dependency on foreign oil and reduce diesel emissions.

At Hunter & Hunter Trucking, we do not feel that LNG will or should replace the use of all diesel fuel applications. BUT, that it (LNG) should be used where it is best suited and that is exactly what we are doing. Local delivery and regional short haul trucks (under 450 miles) making trips in and out of heavily- populated cities, have caused pollution levels to reach all- time highs.

LNG is an alternate fuel that is available now and offers immediate solutions for the reduction of diesel emissions, such as the pollution created in the scenario above.

Mr. & Mrs. Hunter are also partners in The Clean Air Partners Transportation System Natural Gas Train and Intermodal Project (CAPTS) involves moving container freight using LNG.
Click here to read more on this project and visit the CAPTS Website

Several interesting facts about LNG:

WHAT IS IT?
When natural gas is cooled to a temperature of approximately –260°F( at atmospheric pressure) it condenses to a liquid called liquefied natural gas (LNG). In its liquid state LNG takes up about 1/600th the volume of natural gas at a stove burner tip,. and weighs less than one- half of water. It burns only in concentrations of 15% when mixed with air. Neither LNG, nor its vapor, can explode in an unconfined environment; it must be compressed, i.e. in an engine.

COMPOSITION:
Natural gas is composed primarily of methane (typically, at least 90%), but may also contain ethane, propane and heavier hydrocarbons. Small quantities of nitrogen, oxygen dioxide, sulfur compounds, and water may also be found in “pipeline” natural gas. The liquefaction process removes the oxygen, carbon dioxide, sulfur compounds, and water. The process can also be designed to purify the LNG to almost 100% methane.

HOW IT IS STORED:
LNG tanks are always of double wall construction with extremely efficient insulation between the walls. Large tanks are low aspect ratio (height to width) and cylindrical in design with a domed roof. Storage pressures in these tanks are very low ( less than 5) psig. Smaller quantities (70,000 gallons and less) are stored in horizontal or vertical vacuum-jacketed pressure vessels. These tanks may be at pressures ranging from less than 5 psig to over 250psig. LNG must be maintained cold (at least below - 117°F) to remain a liquid, independent of pressure.

HOW IS IT KEPT COLD?
The insulation, as efficient as it is, will not keep the temperature of LNG cold by itself. LNG is stored as a “boiling cryogen”, that is, it is a very cold liquid at its boiling point for the pressure it is being stored. Stored LNG is analogous to boiling water, only 470° colder. The temperature of boiling water (212°F) does not change, even with increased heat, as it is cooled by evaporation (steam generation). In much the same way, LNG will stay at near- constant temperature if kept at constant pressure. This phenomenon is called “autorefrigeration”. As long as the steam (LNG vapor boil- off) is allowed to leave the tea kettle (tank), the temperature will remain constant.

If the vapor is not drawn off, then the pressure and temperature inside the vessel will rise. However, even at 100 psig, the LNG temperature will still be only about -200°F.

HAVE THERE BEEN ANY SERIOUS LNG ACCIDENTS?
[See also A Brief History of U.S. LNG Incidents.]
First, one must remember that LNG is a form of energy and must be respected as such. Today, LNG is transported and stored as any other liquid fuel. Before the storage of cryogenic liquids was fully understood, there was a serious incident involving LNG in Cleveland, Ohio in 1944. This incident virtually stopped all development of the LNG industry for 20 years. The race to the moon led to much better understanding of cryogenics and cryogenic storage with the expanded use of liquid hydrogen (-423°F) and liquid oxygen (-296°F). LNG technology grew from NASA’s advancement.

In addition to Cleveland, there have been two other U.S. incidents attributed to LNG. A construction accident on Staten Island in 1973 has been cited as an “LNG accident” because the construction crew was working inside an EMPTY, WARM LNG tank. In another case, the failure of an electrical seal on an LNG pump in 1979 permitted gas to enter (not LNG) an enclosed building. A spark of an indeterminate origin caused the building to explode. As a result of this incident, the electrical code has been revised for the design of electrical seals used with all flammable fluids under pressure.

WHAT IS CNG?
Compressed natural gas (CNG) is natural gas stored in welding bottle-like tanks at pressures up to 3,600 psig. Typically, it is the same composition as the local “pipeline” gas, with some of the water removed. CNG and LNG are both delivered to the engine as low-pressure vapor (ounces to 300psig). CNG is often misrepresented as the only form of natural gas that can be used as a vehicle fuel.

WHAT IS LPG?
Liquid petroleum gas (LPG, and sometimes called propane) is often confused with LNG and vice versa. They are not the same and the differences are significant. LPG is composed primarily of propane (upwards of 95%) and smaller quantities of butane. LPG can be stored as a liquid in tanks by applying pressure alone. LPG is the “bottled gas” often found under BBQ grills. LPG has been used as fuels in light- duty vehicles for years. Many petrol stations in Europe have LPG pumps as well.