Imagine trying to construct a chemical plant without a piping and instrumentation diagram (P&ID). Just get a bunch of people together at a site and tell them to “make it happen.” Could the plant be built? Well, maybe, but the task would certainly take longer and the result would be a confusing maze of systems, some incomplete and many working at cross purposes. Once the plant is finally done, the operations staff would probably spend all their working hours simply untangling the mess made during construction.
Clearly, the P&ID makes the job easier and leads to a better plant. Similarly, such a blueprint — an energy assessment or audit — is crucial for successfully controlling energy costs. It will underscore the value of system-wide improvements, pursued in stages so that process interruptions are minimized, and of using early savings to pay for later projects. Trying to manage energy without an assessment will yield results that at best fall short of expectations or at worst interfere with the plant’s core mission.
An energy assessment provides a summary of how much energy is input to a plant and its distribution to various departments and systems. It summarizes fuel, power and water use required by process activities as well as by site heating, ventilation, lighting, sanitation, etc. The assessment summarizes energy inputs over a period of time (usually a year) and expresses consumption relative to production levels and weather conditions.
Plant managers often resist the suggestion of conducting an energy assessment. Perhaps the most common objection is: “We don’t have the money to pay for an assessment.” Let’s say we’re talking about a typical medium-sized plant that spends perhaps $2 million on energy each year. Studies by the U.S. Department of Energy and others suggest that the average facility can cut 10% to 20% of its energy consumption. Having a 10% potential savings equates to admitting that $200,000 is being wasted annually. A very good energy assessment might take a few days and cost about $20,000. So, what we’re really being told is: “We don’t have the money for an energy assessment because we need to pay for the fuel that we’re going to waste.” Too bad, because it only gets worse: energy prices are likely to rise faster than the price of an assessment. Plus, energy assessments often can be had for free through utilities, state energy offices and university-based industrial assistance programs (see www.oit.doe.gov/iac).
The knowledge gained from an assessment will return value in many ways:
- The audit itself probably will reveal a number of low- or no-cost adjustments that immediately pay for themselves. One good example is shutting off steam mains that serve abandoned process lines.
- Armed with knowledge of its energy consumption, a manufacturer has a lot more leverage to negotiate contract terms with marketers through whom fuel commodities are purchased. Marketers earn fees based on the amount of fuel they broker; an uninformed energy consumer gives the marketer a blank check.
- Energy consumption information provides a baseline for quantifying the actual impacts of energy improvements. Managers can’t claim victory if they don’t know where they started.
- Baseline energy data help decision-makers prioritize improvement opportunities by targeting the prime movers that consume the most fuel.
- Knowing fuel consumption is essential for accurately determining the operating costs of individual pieces of equipment — and thus for understanding the need for upgrades, replacement or fuel-switching.
- The assessment also provides an inventory of emissions sources. It will present and prioritize opportunities to reduce the risk of non-compliance with emissions regulations.
The energy assessment is a blueprint — a business plan — for improving plant performance through smart energy choices. As the term “business plan” implies, outcomes aren’t accomplished all at once but as a part of a measured process. A business plan will identify resources, milestones and planned outcomes. Perhaps most importantly, an energy assessment describes how a plant manager can make energy decisions that contribute directly to business goals.