Stick-Built or Modular Design for Power Plant Projects? Actually, Both.

More than 10 years ago, power plants were traditionally stick-built, with each building custom designed and made for that particular plant. The major benefits of this approach were maintenance access and lowest equipment pricing, since a substantial portion of the work was being completed in the field.

Fast forward a few years and three factors started instigating a change in philosophy: centralized organizations, rising construction costs and real estate issues.

• Companies started consolidating and sharing resources with a corporate office. This moved decision makers away from plant personnel so maintenance access was often an afterthought. The out of sight, out of mind problem.

• Construction companies often ran unchecked, and Owners were subjected to price escalations due to labor uncertainties inherent with field work, mainly productivity (driven by labor force availability/quality and site weather). This increased schedule risk and uncertainty which drive up cost.

• The concept of Distributed Generation, as well as the increased challenge/cost of acquiring land has reduced power plant site acreage dramatically.

The result was the rise of a new buzzword: Modularity. This concept eliminated (or mitigated) all three of these factors – increasing acceptance and popularity of modular design. For the next several years the focus shifted to these concepts:

• Repeatability: design the system once and then use it at every site, reducing engineering costs

• Minimize field time: Deliver the system as building blocks that can be assembled both faster and easier, thus reducing site schedule risk. Labor productivity can be maximized in the controlled environment of a shop or factory.

• Scalability: relegate equipment to catalog items that could be scaled up or down for a specific opportunity

This philosophy continued to dominate the industry for the better part of a decade, and in some cases still does.  However, as these highly modularized plants start reaching mid-life, maintenance requirements are increasing. As plant personnel attempt to perform these services they are introduced harshly to one of the biggest weaknesses of modularization: ACCESS. There simply isn’t enough space to perform the required work, which means intended ‘permanent’ structures or equipment is being temporarily relocated to improve access. This inevitably increases the time and cost of maintenance. The result is that during the next planning phase, there are often decisions made resulting in sacrifices between aspects of stick-built versus aspects of modularization.

Let’s look at the pros and cons of each:

There will inevitably be examples from the ends of the spectrum, both where traditional stick-built has its merits and where full-blown modularization is required.  However, for the majority of projects falling in between these extremes it’s time to evolve the thinking of the either/or, mutually exclusive relationship to a hybrid design that offers the best of both stick-built and modular.  While the general philosophy should be identified, customization and maintenance access need not be sacrificed for project schedules and scalability.  Instead of breaking the mold, let’s just evolve it.