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RNG Interconnects for Developers, Owners, & Operators; Connecting the Dots

Posted by Gregory Wilk on Thursday, December 7, 2023

If you are a Renewable Natural Gas (RNG) Developer trying to get your RNG to market, or a pipeline company receiving that gas, you know there is one common denominator in your project; the importance of an interconnect! It is the piece that connects the RNG supply source to the gas pipeline network, linking supplier and distributor.

There are many different things that go into choosing your interconnect option, but don’t stress! We know you are busy thinking about all your other project needs, so we mapped out the steps and considerations for you…

Considerations for RNG Developers

Feasibility – It is important to evaluate all interconnect options around the project area. If you are fortunate to have multiple pipelines owned by different companies surrounding the project, you can evaluate the options and potential costs. Each pipeline company’s construction costs will vary, and they may also have different gas quality requirements. Strict gas quality requirements may add significant cost to an RNG project. Some companies may also not have the capacity to receive the produced RNG year-round. If pipeline interconnect costs are too high or if there are seasonal curtailments, then a virtual pipeline to a different location may be another option.

FEED studies are an early planning investment that can pay huge dividends.

RNG Pipeline - Installing an RNG line to the interconnect location could be required or could be an option to save money. In this event, a feasibility study or FEED study is recommended. A FEED study is a low-cost upfront option that evaluates pipeline routes, environmental impacts, and permitting requirements so you can make an informed decision.
Regulatory Compliance – Installing an RNG pipeline to an interconnect location; whether it is 5 miles or 50 feet, requires an evaluation of how it would be categorized by federal (PHMSA) and local state agencies. Evaluating these regulations helps provide an understanding of pipeline ownership responsibilities and ensures compliance with federal and state laws that are critical for a safe and reliable operation.

Considerations for Pipeline Companies

Evaluation – Gathering information is the first step in evaluating the addition of an RNG supplier to the system. Below are some criteria to consider:

RNG flow (min, max, average) and seasonal variations
RNG pressure and temperature
Source of the raw biogas
Gas Quality – Can the RNG developer meet the required gas quality specifications?
Will the RNG developer require fuel gas for their process?

Design – The design of an RNG interconnect is similar to the design of a typical gate station, but requires some unique considerations:

Gas Analyzers – Various analyzers will be selected for continuous monitoring. The types of analyzers selected will depend on the contaminants of concern in the source biogas.
Emergency Shutdown (ESD) Valve – an automatic ESD valve will need to be positioned so it can close to prevent the pipeline distribution system from receiving out-of-spec gas.
Gas Sampling locations – The sampling point for the gas analyzers should be positioned upstream of the ESD valve so the ESD valve can close if out-of-spec gas is detected. An additional gas sampling point should be considered for laboratory sampling.
How will out-of-spec gas be cleared from the gas analyzer sampling point? A recirculation line can be added to send out-of-spec gas back to the RNG company to be flared or sent through their conditioning process.

Operations – Before the station is operational, an Operations Plan should be developed to outline the responsibilities of both parties. Potential items to include in the Operations Plan are:

Description of the interconnect facility
Gas Quality requirements
Data sharing of gas quality readings
Laboratory sampling process and frequency
ESD shut-in criteria and restart process
Operational contacts for both parties

If you would like to further discuss what makes the most sense for your project moving forward, please reach out. We would love to help you to [inter]connect the dots!