Codes and Standards for Renewable Gas Pathways

Citation

  • Driscoll, I., Facey, R., Kowalishen, K.J., Moore, B. (2022). Codes and Standards for Renewable Gas Pathways. Current Status and Future Directions. Canadian Standards Association, Toronto, ON.

Executive Summary

Renewable gas is produced from a renewable resource that can be replenished. It is often produced from a range of agricultural products and by-products (such as crops, livestock manure, and biowaste). Green hydrogen (electrolytic hydrogen produced using a renewable power source like solar or wind) is also a renewable gas. Non-renewable gas is produced from sources that will deplete or cannot be replenished, such as fossil fuels like coal or natural gas.

The renewable gas production potential for Canada, the United States, and the world is significant, with current production being underutilized, especially in Canada. To meet its Paris Accord requirements, Canada must reduce greenhouse gas emissions dramatically and displacing natural gas with renewable gas will contribute to these reduction efforts.

This research report reviewed existing renewable gas standards landscape to identify needs and gaps by completing a comprehensive literature review, consulting experts, and analyzing information provided by key industry stakeholders via questionnaires.

An integral part of this research was defining renewable gas pathways, providing process descriptions for their production, and creating simplified block flow diagrams for each pathway. This was done to provide context for identifying current codes and standards (along with any gaps) used in Canada, the United States, and Europe.

Existing codes and standards in Canada and the United States that support the oil and gas industry are also used for designing and constructing renewable gas system components. Some standards and guidance documents have been specifically developed for renewable gas.

A common comment from questionnaire respondents was the lack of standards and codes for approved renewable gas production pathways that provide guidance relative to feedstocks, production, and renewable gas quality. Designers of these facilities must determine which codes and standards to apply; they often rely on international ones, without understanding the basis or the methodology behind them. An overall guide on applicable codes and standards for each pathway (a roadmap) would be useful for designers.

Renewable gas production pathways considered established and mature involve first generation technologies like anaerobic digestion of organic waste and splitting water molecules using electrolysis to produce green hydrogen. One of the many challenges of renewable gas in gaining initial market access is that the natural gas supply infrastructure is typically not near these production plants. Emerging second generation technologies involve converting biomass via gasification and steam reforming or methanation into renewable hydrogen or renewable natural gas. These technologies are not yet financially viable but stand to produce renewable gas in significant volumes by deploying central production.

The gaps identified for codes and standards are summarized as follows:

Standard/code topic Identified gaps
Feedstock Codes and standards for feedstocks of renewable gas pathways are scarce. The variation of feedstocks and their variability in composition, especially for biomass, are technical challenges addressed during system design (i.e., selection of appropriate technologies and the arrangement of the processes) but do not constitute an area that necessarily needs to be heavily standardized. A code or standard defining acceptable feedstocks (nature and types of contaminants) would prove useful. Adopting international codes for testing various feedstocks (tests for contaminants and biogas potential) would also help designers.
Production and Storage For biogas and renewable gas, research is required to determine whether additional design features need to be incorporated into the construction materials for the equipment and processes used (specifically anaerobic digesters and biogas storage).
For electrolytic hydrogen, additional research and development are required; this work concerns linear power/generation for hydrogen production, storage methods and materials, reactor design, and system performance and efficiency (i.e., operation and maintenance, electrolyte conductivity, and material stability and durability).
Product Quality No standardized specifications or guidelines were found specifically for renewable natural gas. A lack of consistent standards for the RNG specifications were noted by questionnaire respondents as hampering their design and implementation efforts.
Potential feedstock contaminants that could end up in the renewable hydrogen gas can affect the willingness of utility companies and end-users to use that hydrogen or affect its allowable quantity. The unknown presence of feedstock contaminants requires research for determining contaminant types and their potential impact on hydrogen production. Existing specifications for hydrogen fuel cells could be referenced for renewable hydrogen testing procedures and quality standards.
Transmission Applications and End-Use The acceptable levels of contaminants in renewable gas originating from digestion of different feedstocks and their long-term impact on the production equipment, transmission system, instrumentation, pipelines, and the end-use equipment is unknown.
The integrity of the existing natural gas distribution network with long term exposure to elevated levels of hydrogen at high pressures seen in the transmission systems is unknown. The achievable amount of hydrogen to be injected into Canada’s and North America’s existing transmission system needs to be studied and identified to account for different gas end users and for different construction materials in the pipeline systems. For new pipeline construction, a new code or standard could be applied but may have to be addressed on a case-by-case basis for existing transmission systems.
Safety/Risk Research and development are required to fully understand the physical mechanisms of renewable gas diffusion as they relate to gas build-up and combustion in enclosed spaces, flammable cloud formation, ignition, deflagration-detonation transition, and renewable gas flashing, pooling, and vaporization. Components and systems need to be tested under operational and environmental conditions that replicate real-world use to confirm the safe and effective operation of renewable gas technologies.
The contaminant potential of some components (like arsenic and mercury) in renewable gas needs to be understood.
Overall Guide An overall guide on the applicable codes and standards for each pathway (a roadmap) would be useful for designers. This report can be a supporting document for the initiative to develop the necessary regulations.