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Stray voltage and other threats to pipeline safety
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Charles Rhodes, Xylene Power
Recently an Illinois resident named Julie Newhouse sought my expert opinion with respect to a proposed wind farm to be built in Boone County, Illinois, adjacent to an existing major Enbridge oil pipeline. I am told that this wind farm is to include numerous wind generators geographically distributed close to the pipeline route. I believe that the wind farm developer contemplates generator interconnection via home run buried cable.
Most wind farms are located in rural areas where stray ground current between nearby wind generators is not a matter of serious concern. However, when multiple generators are located adjacent to a buried metal pipeline there are many ways for stray ground current to cause accelerated pipe corrosion, unless specific isolation measures are taken at each generator to prevent stray ground current. Implementation of such isolation measures may significantly increase the total cost of a wind farm.
If the electrical equipment includes power inverters, as do some wind generators, then stray ground current may have a substantial DC component, which can aggressively attack a nearby long metal buried pipe at any scratch or defect in its surface coating. …
In my view, the potential costs related to rupture failure of the Enbridge oil pipeline could far exceed the financial capacity of the wind farm owner and/or his liability insurers to pay. Moreover, US law might not even hold the wind farm owner liable for electrically induced pipeline corrosion.
It is essential that this issue be addressed immediately by Boone County, irrespective of lack of applicable electrical code and/or property related regulation.
Under no circumstances should Boone County permit construction of this wind farm to proceed until the wind farm electrical plans and specifications have been approved by an independent professional engineer with expertise in distributed generator isolation and metal pipeline corrosion protection. Similarly, no permit should be granted for wind generator operation until the installed wind generation equipment has been independently checked for conformity with the isolation measures contained in the plans and specifications approved by the independent professional engineer. …
Also see: Statement of Dr. Charles Rhodes on the potential for electrically accelerated pipeline corrosion leading to a pipeline rupture and/or natural gas fire – Alberta Utilities Commission, Proceeding Number 1955, Hearing for development of wind power plant and associated substation in the Provost area (“Bull Creek”)
Richard Kuprewicz, Accufacts
Accufacts was asked to provide independent observations related to the proposed installation of a multi-megawatt wind turbine farm “Project,” last estimated at approximately 200 MW, to be installed over, or in close proximity to, two existing liquid transmission pipelines sharing a pipeline right-of-way, or “ROW,” in Boone County, Illinois …
While an offset distance from the pipeline ROW is one possible way to approach certain threats to the existing pipelines, Accufacts believes, after reviewing Attachment 1, that such an approach may not adequately deal with the threats to the pipeline that can be associated with the Project. Federal pipeline safety regulations place specific obligations on Enbridge, the pipeline operator, to assure the safety of the pipeline from various threat activities that may exist off, as well as on, a pipeline ROW. Local and state agencies should be able to place as a condition of a permit approving the Project, that certain precautions including prudent engineering analysis have been performed, documented and are sound (usually subject to independent verification). …
Accufacts sees at least three categories of threat to the pipelines from the Project:
- external loading threats,
- misplacement or improper alignment of the wind turbines, such that tower loads or turbine blade failure could reach the pipelines, and
- stray current effects from the Project’s electrical system.
Under federal pipeline safety regulation, all of the above risks are the responsibility of the pipeline operator whether the threat is on or off the pipeline ROW. The pipeline operator should be able to demand certain requirements such that the Project will not threaten the pipelines. Local agencies should be able to mandate and require adequate proof and documentation from the pipeline operator that these threats have been prudently evaluated and resolved in the final design, its placement, and the Project’s operation. …
The potential for electric generation/transmission stray current interference to quickly rip the steel from buried pipelines, even very deep pipelines, is well understood and known in the pipeline industry. … The pipeline is well within its rights to demand and understand the Project’s electrical design/installation and its possible impacts to generate stray current on the pipelines.
