Applications and Benefits of Real-Time Energy Measurement

Applications and Benefits of Real-Time Energy Measurement

By Michael Lukasiewicz, Gas Research Institute, and Stephen Maselli, AMETEK

The Gas Research Institute`s (GRI) support of research, conducted to develop a low-cost technology for measuring gas energy, promises to address an industry need resulting from Federal Energy Regulatory Commission (FERC) guidelines. The regulations require charges to be based on the therm value of the commodity. Consequently, having the ability to accurately measure, at a low cost, the energy content of natural gas at the point of delivery will provide a level of confidence previously unavailable to the industry.

GRI recognized industry business areas that could benefit from the direct measurement of heat content, and sponsored the research to address those needs. The result of this research, the Therm Factor Transmitter (TFT), was a high-precision microcalorimeter designed to be installed and operated in a wide variety of field operating conditions with minimal support or field visits.

Gas Industry Needs

The first need relates to the marketing changes that resulted from open access to the gas system (FERC Order 636) and the requirement that all transportation and contract pricing be based on the therm content of the gas fuel. Transportation customers, which comprise many of the industry`s largest customers, can now purchase gas directly. In fact, nationally, 40 percent of sales are transportation gas. Some major companies report that nearly 70 percent of sales are transportation gas. FERC Order 636 also enables competitive marketers to have access to the transportation system. Consequently, there is an increasing need to more precisely allocate charges for this service.

Changes in the supply market making the gas heat content more variable is another area where direct measurement of heat content would be beneficial. A strong market combined with regional supply constraints have prompted the introduction of new gas production and transmission lines. The new sources include:

Canadian gas that is stripped of the heavier hydrocarbons and is nearly pure methane (980 Btu).

Local production that can vary depending on the fields. The Btu content range from 1,000 Btu (in some cases even as low as 880 Btu due to high inert levels) to nearly 1,200 Btu.

Biogas manufactured from the decomposition of waste material (often at a landfill or recycling center). This gas is at best pure methane and contains 980 Btu. However, if production is not carefully controlled, contamination can dilute the gas and Btu content may suffer.

Benefits of Direct Energy Measurement

The low-cost ability to measure the Btu content of natural gas presents opportunities and choices that have never before been practical. There are some significant benefits achievable with minimal change in the business practices of a local distribution company (LDC). Benefits include improved measurement techniques, reduced operating and maintenance expenses, and increased system operating data provided.

Monetary charges for custody transfer and contracts are based on commodity quantities expressed in therms. Con sequently, refinements achieved in the precision of therm definition will result in more authoritative billing. The ability to directly measure therm values will help LDCs maintain a dominant role in the measurement and determination of customer use. Since the charges for use of the system are based on the commodity, improvements in measurement will result in more precise customer billing. Customers having patterns of use that differ significantly with their contracted supply can be provided with the information necessary to bring their use “in balance” with their purchases.

For customers willing or unable to achieve balance, the LDC will be able to accurately levy out-of-balance charges. The ability to directly measure therm values also allows for providing customers with heat content data for process or other types of monitoring or control purposes. The capability offers a potential source of new revenue, such as billing for data connection, as well as the potential for improving customer relations.

The TFT has storage and direct communications capabilities, which eliminate the expense of collecting and maintaining a grab sample system. The TFT requires minimal field visits to check operation. If the TFT is equipped with a direct communications link, it will set off its own alarm in the event of any malfunction. Expendables used in the operation of the TFT include the battery, reference and carrier gas, and sensor bead. On an annual basis, the cost is of expendables is approximately $300 to $400.

The additional system operating data provided by the TFT can be very useful for defining therm zones. It can be used to augment SCADA data inputs as a supplement to “Stoner” modeled flows as well as for improved flow definition, which can be invaluable in responding to emergencies that interrupt supply or major distribution facilities.

Because of its significantly lower cost, another benefit of the TFT is in the area of gas purchasing. The TFT can be used to supplement the role of the gas chromatograph (GC) by providing therm measurement at sources where GCs are not cost effective. This facilitates the use of local production sources, particularly those that may have significant variations in Btu levels and can provide needed capacity at economically attractive costs.

Another way in which the TFT can augment the GC in the therm measurement process is by making it possible to measure downstream of custody transfer sites where it is not cost effective to measure therm content with more costly technologies.

In addition, the TFT provides the ability to take biogas into the system. Biogas can be very low Btu gas and often may require enrichment in order to maintain system requirements. Because the TFT provides the ability to accurately measure the gas source, it is possible for LDCs to control the enrichment process.

Often community waste disposal systems will include a process that manufactures biogas. The ability to take this gas into a system without creating customer dissatisfaction builds good will. The measurement capability of the TFT can facilitate the LDC`s ability to partner with local government to help resolve the community`s waste disposal needs.

Transportation Gas Sales on the Distribution System

The more precise therm definition provided by measuring heat content with GCs and TFTs at the city gates or custody transfer stations can be applied with more customer-specific definition by directly measuring the Btu delivery of the system`s larger customers.

Direct on-site measurement also provides the data necessary to reduce potential errors that occur by calculating the pipeline mix of multi-sourced areas of identifying lags between the time the gas passes the point of custody transfer and the time it is actually delivered to the customer.

Ultimately, the TFT would enable more precise allocation of an individual customer`s use and, consequently, charge appropriately for use of the system. Volumes alone do not reflect transportation costs. Higher fuel volumes will be required for those fuels with lower Btu content, which is why customer billing based on therm measurements must reflect the actual energy value of the fuel.

When installed on the inlet to the compressor unit (filling storage), the TFT facilitates wholesale billing because of the improvement in heat content measurement. In addition, it makes it possible to identify the high Btu components that may occur in the gas supply and could potentially damage the natural gas fueled engine.

Roles of the Project Participants

GRI has nurtured this research project by providing essential funding and proactive project management that has both insured proper momentum and reduced the financial risks to acceptable levels.

Transducer Research Inc. pioneered the technology by developing the initial design and demonstrating the potential of this measurement technology. AMETEK provided the design modifications and developed the reengineering necessary to make the TFT commercially viable. Effective Technologies is providing the technical oversight and analysis to facilitate the application and introduction of this measurement capability into the daily business of the natural gas industry.

The Future of Therm Measurement

More widespread use of therm measurement in the industry can result in new marketing strategies and increased profitability when it is applied on a real-time energy measurement (RTEM) basis. The timely identification of supply costs and distribution system loading can make it possible to serve new markets.

For example, this capability would facilitate recruiting of seasonal loads such as those characteristic of asphalt plants, agricultural crop drying or manufacturer processors such as canneries. These markets could be easily served and accurately billed because it would be possible to price gas service to reflect actual live market conditions and individual customer usage.

The capability to apply RTEM can also be used to recruit electric loads that contribute to the electric system peak and, therefore, are subject to premium seasonal electric charges.

Many public and municipal facilities such as hospitals, water systems and public offices or service complexes are equipped to withstand by-generation which enables them to power essential systems in the event utility service is interrupted.

Electricity generated with low-cost gas could supplement the peak demands (peak shaving) and lower the electric demand and energy charges. This can provide a substantial savings to these customers, require minimal investment on their part, and when the charges are billed on the actual market price, the costs can be indexed to live market conditions.

Currently, most transportation customers are subject to monthly balancing and they have the ability to utilize system capacity without incurring a direct charge for this access. Since RTEM provides the mechanism to identify and quantify this practice, a reasonable pricing schedule can be developed based on the directly measured amount of gas used by an individual customer.

Hourly balancing will identify the extent of system “storage” use. Ideally, gas transportation should flow through the pipeline and be consumed as it is delivered. Hourly balancing will identify deliveries taken at the gate station and not used by the customer at the time of delivery.

Systems subject to capacity constraints can develop pricing incentives that can facilitate load shedding based on live cost conditions. Customers can be provided opportunities to turn off the system in exchange for a shedding bonus. This can reduce the LDC`s capacity costs or even allow the LDC to market the added capacity and share the premium pricing with the customer that shed load to make the capacity available.

A proactive marketing program utilizing the opportunities discussed above can be used to identify and eliminate profit niches that either are or might be exploited by gas brokers and competitive marketers by facilitating the development of: competitive rates for specific applications, time of day rates and capacity billing rate structures similar to electric rates.

Because of the foresight of GRI and the dedication of the entire team, a new metering tool will soon be available to the natural gas industry. This new tool is coming at an opportune time and can provide the information needed to make value-added decisions on energy use.

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The Therm Factor Transmitter (TFT) is a high-precision microcalorimeter that has been designed to operate with minimal support. Field visits are seldom necessary, since the consumables (battery, reference gas and bottled air) will cycle up to 10,000 times before requiring service. The device also has substantial memory for data storage and can be linked to a remote data collection system via a modem-telephone system or an RTU. The TFT is capable of functioning in temperatures of minus 40 to plus 70 C and is enclosed in a weather-tight case to permit direct installation in a wide variety of field operating conditions.

Conceptually, the TFT is conventional in design. A small quantity of dilute reference gas is transported to the catalytic bead. A small amount of electric power is applied to oxidize the reference gas. Then a small amount of flowing gas is processed in the same manner. In each case a small amount of electric power is used to create a preset level of heat. The make-up power is compared, and the difference between the power added to the reference gas and the gas flowing determines the Btu content of the fuel. An internal microprocessor, programmed to adjust the system for local operating conditions, performs all of the calculations using field tested algorithms and formulas.

Although the principles of operation seem basic, the technological challenges have, at times, been daunting. Creating a gas sampling system with miserly power needed to keep battery use down to acceptable levels and, at the same time, have the system function with high reliability in the wide range of temperatures requires a compromise between the design needs and the hardware limitations.

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GRI`s Therm Factor Transmitter

Author

  • The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at Jennifer.Runyon@ClarionEvents.com.

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The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at Jennifer.Runyon@ClarionEvents.com.

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