As the global population grows, so does the demand for energy — specifically, cost-effective clean energy. One source of energy that will likely play a vital role in years to come is liquefied natural gas (LNG). LNG consists of gases, primarily methane, that are cooled to a liquid form (-258°F) to facilitate safe worldwide transport and storage at relatively low pressures. Later, LNG is returned to a gaseous state and used as fuel, primarily for power generation and transportation.
According to global LNG market reports, the global market demand for LNG is expected to exceed 560 million tons by 2027, expanding at a compound annual growth rate of 5.8%. There are 25 liquefaction export terminals, mostly in North America, planned to come online by 2024. Longer-term studies show that LNG demand is expected to increase to approximately 700 million tons by 2040, further showcasing its probable role in contributing to a lower-carbon energy system.
As a result, LNG liquefaction plant projects have been on the rise. To meet the increasing demand, owners, operators and contractors are looking for safe and effective solutions to reduce costs and mitigate schedule risks. Modularization is one proven strategy that, if used correctly, can help control costs, mitigate project schedule risk, and increase overall safety and quality performance.
Modularization is a construction method where direct labor hours for plant erection — structural steel, equipment, piping, electrical and instrumentation — are accomplished in a controlled shop environment, rather than at the site where uncertainty and risk is greater. The work in the shop is carried out in distinct modules; then, the modules are transported to the site and installed as completed blocks. Modularization is not new to the LNG industry. However, with advancements in the long-distance transport of mega-modules, which weigh anywhere from 500 tons to 6,000 tons, the construction method has become a viable means of overcoming many of the labor, cost and schedule barriers associated with new large- or mid-scale LNG plants.
Given the remote location of many of the large-scale LNG plants, site labor availability has been one of the largest barriers to cost-effective construction. Traditional construction of these plants requires a substantial amount of labor on-site, bringing with it labor density concerns, negative productivity impacts, higher hourly rates, increased supervision costs and, ultimately, safety risk. Although mid-scale liquefaction export terminals in North America may not share the degree of site labor scarcity that much more remote locations experience, the hazards associated with site labor density remain. In contrast, the fabrication of modules can be done in locations where labor is more accessible and stable, construction impacts due to weather are less likely or significantly reduced, and productivity can be maximized by implementing assembly procedures and standards.
Beyond the large- and mid-scale LNG liquefaction facilities are small-scale LNG plants that are projected to provide the bulk of the production for those areas that are not on the larger LNG grid. These plants can be modularized on a much smaller scale, providing the same advantages to cost and schedule while also being more easily transported by truck or barge to the site. Transportation of these modules requires the same focus on logistics as the modules for large and mid-scale LNG facilities.
The challenges of these modules, which are many, include developing a plant layout that incorporates — to the same degree as a stick-built facility — safety in operations, accessibility and maintenance considerations, in a smaller footprint. Additionally, smaller modules require careful engineering consideration in terms of type and location of module interfaces, as well as strict dimensional control in the fabrication shop so that the modules fit properly in the field, and tight cost/schedule advantages are maintained.
Modularization — whether for large-, mid- or small-scale plants — also offers the ability to work many construction tasks in parallel that would otherwise have a finish/start schedule relationship, overlapping schedule task durations to gain schedule advantage and reduce overall construction durations at the site. This holds true for civil activities versus mechanical, as well as typical finish/start mechanical activities where modules can be fabricated and assembled concurrently but ultimately will stack one on top of another at the construction site.
With the COVID-19 pandemic, stress around having stringent protocols in place to keep people safe from disease on the job site is at all all-time high. Navigating solutions to limit exposure from person to person and following CDC guidelines during projects can be challenging. One of the inherent benefits of performing work in a shop environment is the consistent, stable nature of the work and of the people who perform the work daily. These individuals typically live and work in the area — a departure from typical stick-built construction, where workers can come in and out from all over the country, or even the world, bringing with them the risk of heightened exposure. With the reduction in site labor density that modularization provides, the burden of COVID-19 site protocols to construction cost and schedule also may be reduced.
Due to its off-site nature, modularization for any market brings with it heightened logistical concerns for transportation, especially when shipping to other parts of the world. However, early stakeholder alignment, detail planning and comprehensive coordination of the project teams can detail every phase of transportation: construction sequencing, mode(s) of transportation, design for reaction loading, weight control, heavy haul coordination, expected transportation weather windows, government customs requirements and duties, site logistics, and everything in between. With a strong plan in place, modularization can help improve project success.
Successful completion of LNG infrastructure projects requires timely delivery of critical materials. An engineer-procure-construct (EPC) team can streamline the critical path to improve project quality and efficiency.
