With growing interest in liquified natural gas (LNG) as a fuel alternative for power generation facilities, one of the most significant hurdles facing many operators is logistical. How do you get the LNG where it’s needed safely and efficiently? One option being explored in the U.S. is allowing LNG to be transported by rail tank cars.

In October 2019, the Pipeline and Hazardous Materials Safety Administration (PHMSA), in coordination with the Federal Railroad Administration (FRA), published a proposed rule to allow just that. The proposal would allow LNG transportation through the United States in DOT-113 specification rail tank cars. Currently, this is only allowed under special permits from PHMSA or in a portable tank/isotainer with FRA approval. However, these portable tanks do not carry as much volume of LNG as the proposed rail cars.

Natural gas infrastructure remains limited and is nearly at capacity in some regions of the U.S. Moving LNG by rail could free up some capacity in those pipelines for consumers. Additionally, moving LNG by rail would reduce the number of trucks currently transporting LNG on America’s roadways.

Fueling Facilities

As power providers add peak shaving facilities, many operators are looking at putting in a liquefaction unit that can store natural gas as LNG. Generally speaking, they would liquify the gas in the summer when demand is relatively low, and then that stored LNG can be vaporized in the winter or when demand spikes, such as during a polar vortex.

Rail facilities could supplement a liquefaction unit, in the same way that truck loading has become common with existing LNG plants. Rail cars would provide another option to move LNG product between facilities and make it more feasible to move the LNG longer distances. This can provide flexibility for those who need LNG quickly while they build a liquefaction unit, need smaller amounts of LNG in multiple locations, or don’t feel that their LNG demand justifies the cost of a full liquefaction facility.

Rail can be especially appealing for plants that have been converted from coal to other fuels, because these sites typically already have rail access that was used to bring in the coal. Reopening the rail access and using that to bring LNG to their facilities could be a practical option for such sites.

Some new infrastructure still would be needed, such as rail car unloading stations. Facilities would need hoses and other minor infrastructure elements that are broadly available from multiple suppliers since similar equipment is used for LNG truck loading.

Once the LNG is on-site, there are a variety of storage options available. A field-erected tank would provide sufficient volume to fill or unload a full train of LNG. Smaller options like bullet tanks could contain the volume of multiple rail cars and are faster to construct than a field-erected tank. LNG pumps may also be required to load or unload the rail cars, which is the same method used to load and unload LNG trucks.  Storage options and equipment can be customized to the specific site and the existing infrastructure and plot space.

Alleviating Public Anxiety

Gaining support for transporting LNG by rail requires addressing stakeholder concerns about safety risks. Some major rail corridors are routed through   metropolitan areas with high population densities. A number of residents are concerned about the potential for derailment, crashes or other accidents that would lead to a release of LNG or natural gas in their community.

A few LNG facility operators have received special, short-term permits. Those tend to include mitigating factors such as limiting the speed of the train in certain areas, restricting some routes or requiring that they be declared ahead of time, and enhancing communications with other train operators in the area to reduce the risk of collisions.  With the data from these operators — along with experience by other countries who are currently transporting LNG by rail and the safety studies being completed — proponents might be able to alleviate concerns, reassure residents and reduce opposition to using rail for LNG.

Steaming Ahead

Initial plans called for finalizing the proposed rule by the middle of 2020, but the reality is that the supporting studies are not likely to be ready by that time. Many stakeholders would prefer to wait for the studies to be completed so that every contingency has been evaluated and all necessary precautions are put in place. If the studies are completed by the end of 2020, the process of gaining consensus on the results and implementing the results would extend into 2021.

Utilizing rail transportation for LNG could offer an efficient solution to multiple challenges. The U.S. already has rail infrastructure in place that could be used to alleviate capacity issues in other channels. The more LNG that can be moved by train, the less that must be transported by trucks. This has the advantages of reducing roadway congestion and burning less fuel to move the LNG, reducing emissions while also decreasing the cost of the gas for the consumers.

The challenges to implementing LNG transportation by rail are real, but the benefits could be considerable. As the LNG boom continues, the value of alternative solutions like this should only increase.

 

Each of the various options for LNG storage containers comes with its own considerations for plot space, siting and expense. A recent white paper examines the details.

Read the White Paper

by
Sara O’Dell, PE, is a senior project engineer with 15 years of engineer-procure-construct project execution experience, spending the last decade working on LNG projects using both liquefaction and regasification processes for onshore and floating installations.