Among various initiatives to help contain costs and maximize profits, some can produce obvious results that are relatively easy to calculate: switching to a more efficient fuel source, if possible, is one such example. Yet, other less obvious measures can produce equally significant results at the bottom line. A cost-containment initiative that easily escapes recognition involves evaluating the choice of Continuous Emissions Monitoring (CEM) protocol calibration gases.

In 2003, the Environmental Protection Agency conducted a “blind” audit in which new cylinders of protocol calibration gases produced by various suppliers of specialty gases were purchased from an electrical power plant. EPA then sent the cylinders to an independent third party — a testing laboratory where they were analyzed against National Institute of Standards and Technology (NIST) standards, which are regarded as being the most accurate metrological standards available and, thus, often used in the preparation of high-end calibration gases. The audit results showed substantial, if not alarming, variations in the accuracy of the protocol gases examined. Some of the gases were off by 8%. EPA has posted the audit results on its website: www.epa.gov/airmarkets/monitoring/calgasauditpassfail.xls.

When considering whether inaccuracy of a calibration gas really matters, emissions credits — beyond basic compliance issues — are worth noting. Due to faulty preparation or degradation in the cylinder, a calibration gas may provide less accuracy than what is stated on the tag (tag value). Since the tag cites the minimum EPA requirement of ±2% accuracy, contents may still be in the clear regarding actual compliance. Nevertheless, while the tag value is typically assumed to be correct, unless the cylinder certification has expired, EPA's audit results suggest that what is in the cylinder probably does not match what is stated. And, when an environmental calibration gas goes bad, it results in a “too-sensitive” CEM calibration, i.e., it will report inflated emissions values. Accordingly, the number of tons emitted of SO₂, NO_x, CO₂, or VOCs will be overstated, thus losing tens, if not hundreds, of thousands of dollars in emission credits, all due to inaccurate calibration gas.

For example, in the case of a coal-fired cement kiln that emits 10,700 tons of NOx per year, CEM is calibrated using a gas whose accuracy is off by 1%; thus, it incorrectly measures and overstates NOx emissions. Translating this apparently small error to the plant's bottom line, based on NOx credits valued at approximately $2,300/ton, the overstatement will cost the company $246,100 worth of emissions credits it could have banked or traded (1% of 10,700 = 107 tons x $2,300/ton of NOx). Exacerbating matters, since a CEM is essentially a SO₂/NOx/VOC billing meter for both credit trading and for tax purposes, inflated Title V emission fees will be paid to the tune of $45/ton — an additional unnecessary expense of $4,815. Overall, while the plant remains in compliance with EPA regulations, the combined hidden loss totals $250,915.

As the above example suggests, an error of 1% has significant financial consequences: how much greater a price is paid in the case of one of the gases the EPA audit found to be 8% off. Clearly, the potential loss in unclaimed emission credits and unnecessary taxes would be much higher. New trading requirements — including the Clean Air Interstate Rule (CAIR), California Reclamation Rules, the Highly Reactive Volatile Organic Rule (in the greater Houston, Texas area), potential CO₂ Regional Greenhouse Gas Initiative (RGGI) — add even more weight to accuracy in measurement. Increased demand for emissions control will place greater focus on precise measurement and instrument calibration for which accurate calibration gases are essential. ‘Staggering’ is not too strong a term to describe the potential for millions more dollars in lost emissions credits due to “bad” protocol calibration gases.

The hidden cost of inaccurate protocol calibration also includes purchasing unnecessary expensive materials. If an SCR or an SNCR system is being used to reduce NOx emissions and ammonia is injected, potential costs can go higher still. Ammonia is injected at rates based on readings from a NOx inlet monitor.When the inlet monitor is inaccurately calibrated by an unreliable gas, it will detect NOx levels higher than the plant NOx emissions allowance, thus triggering ammonia injection. Every 1 ppm of NOx read incorrectly can result in spending tens of thousands of dollars on unnecessary ammonia or urea. In a natural gas turbine application with an SCR system, for example, a 1 ppm error can lead to injecting excess ammonia that, at today's price, is worth over $30,000/year.

A company can reduce cost and avoid unnecessary expenses as well in less dramatic, though substantial ways. Given the value of an employee's time, choosing a gas supplier that offers Internet and IP technology-driven e-tools reduces administrative and managerial expenses. Tracking cylinder expiration, for example, provides an opportunity to implement such efficiencies. When a protocol cylinder reaches the expiration date shown on its Certificate of Analytical Accuracy, the contents can no longer be trusted to remain within 2% of the listed “tag value,” and under EPA guidelines, the gas is no longer compliant with test methods for emissions. If the cylinder retains enough gas pressure (500 psi), it can be returned to the manufacturer for possible recertification. However, this problem is easily avoided by using a gas supplier that automatically provides notification before a cylinder's expiration and a warning each time a cylinder in the inventory expires to avoid its continued use.

Obtaining Certificates of Analytical Accuracy and MSDS documentation is now possible online. These documents are important for test verification and completion of most Part 60 tests. The ability to produce the documentation when needed can save hours of organization. If a gas supplier provides Internet access to detailed historical data that includes cylinder certificates, contents, ship and pickup dates, proving protocol gas compliance in the event of an audit will be as easy as a click of the mouse. Industry averages estimate clerical costs at $65/hour, and traditional purchasing costs at $150/order. So placing orders, checking delivery status, filing documents, and scheduling empty-cylinder pick ups are additional cash drains for plant operators. Accomplishing these tasks online saves additional money by reducing costs to a flat $25/hour/order.

For cost containment and new sources of revenue, therefore, operators are advised to look beyond obvious measures and consider a factor not visible to the naked eye: the accuracy of protocol gases used to calibrate CEM. Then, taking a critical look at services provided by the specialty gas supplier is key to boosting the bottom line.

This article is adapted from materials supplied by Leanne Merz, director of technical services, Scott Specialty Gases, Inc. To contact the author, please call 1-800-21SCOTT. For more information on the company or its products, go to www.scottgas.com