The growing variability in the composition of natural gas delivered to American consumers is creating a number of new operational, reliability and safety concerns, but a coalition of industry representatives told FERC last week that substantial research remains to be done before recommendations can be made on how to deal with the problem.

A large number of industry trade associations and research organizations have been taking a collaborative approach on gas interchangeability but they told FERC the subject has been challenging because of a dearth of information on how gas equipment — from appliances, to pipelines and power plants — respond to variations in gas quality and heat content.

They presented the Commission with a draft white paper last week on hydrocarbon liquid dropout issues, but said much work still must be done on gas interchangeability. Donald Santa, president of the Interstate Natural Gas Association of America and spokesman for the coalition, said the group is discussing research funding with the Department of Energy.

Despite the long history of the domestic gas industry, gas interchangeability only recently became an issue because high prices and domestic supply concerns have attracted gas with differing compositions from all over the world. High prices also have made it more economic for producers to keep liquids in the gas stream rather than pay for processing.

“The quality of the natural gas has not been an issue in the United States [until now],” noted Evan Gaddis, president of the Gas Appliance Manufacturing Association. “There is a lot of experience in Europe, Japan and through Asia, where they have used liquefied natural gas for quite sometime. Historically it has not been an issue for the manufacturer or the consumers here because historically we have been able to deal with the quality [of gas] that we work with.

“Now with the introduction of foreign gas that is coming in, that’s changing and we’ll look at the effects on the life cycles of our products, the increase in carbon monoxide [and] nitrogen dioxide. We are looking at a decrease in shelf life, we believe, and also a decrease in efficiency.”

Variations in the composition of gas can create a variety of problems for natural gas equipment. Chuck Linderman from the Edison Electric Institute told FERC that regasified LNG has led to efficiency and emissions problems, such as increased nitrous oxide and “brown plumes,” at power plants in South Korea. He said variations in gas composition have the potential for causing reliability concerns due to operational problems, such as turbine vibrations. General Electric said it can make a power turbine that runs on any fuel but its machines can’t handle changes in fuel quality without adjustments being made, said Linderman.

The coalition plans more in-depth study of these issues, including an examination of how the Asian, Australian and European gas industries have dealt with them.

“There is a wide variety of combustion related and noncombustion related gas composition requirements that must be served, ranging from residential and commercial end users on one hand to…processing sensitive industrial users,” said Santa. “In some cases, the tolerances for such compositional variations have not been studied and publicly available information has not yet been developed.”

Santa noted that an important issue for residential customers is the absence of controls that can be used if a potentially harmful gas composition makes its way into their home. Larger end users also may be affected by rapid changes in the compositional variation of gas. Such changes could impact reliability, safety and equipment integrity.

He said the task group intends to develop technical guidance for FERC that will “facilitate adopting interchangeability specifications that can balance the potentially conflicting goals of addressing the needs of most consumers, posing the fewest constraints on gas supplies and preserving the safety, reliability or integrity of end users and equipment.”

The task group intends to present a white paper to FERC on gas interchangeability by the end of October. The paper will focus mainly on technical issues, leaving the policymaking largely up to the Commission, Santa said.

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