Renewable natural gas (RNG) has emerged as a promising low-carbon feedstock for hydrogen production through steam methane reforming (SMR). Derived from landfills, anaerobic digestion, and agricultural waste, RNG offers a pathway to reduce greenhouse gas emissions compared to conventional natural gas while leveraging existing SMR infrastructure. Evaluating its role requires an analysis of carbon footprint, scalability, policy frameworks, and real-world applications.

The carbon footprint of RNG-based hydrogen production is significantly lower than that of conventional natural gas. RNG is produced from organic waste materials that would otherwise decompose and release methane, a potent greenhouse gas. By capturing and utilizing this methane, RNG avoids emissions that would contribute to climate change. When used in SMR, RNG can achieve a carbon intensity reduction of up to 70% compared to fossil-based natural gas, depending on the feedstock source and production process. For example, RNG from dairy manure via anaerobic digestion can result in negative carbon intensity due to avoided methane emissions and co-benefits like digestate fertilizer production. In contrast, conventional SMR emits approximately 9-10 kg of CO2 per kg of hydrogen produced, while RNG-based SMR can reduce this to 3-4 kg or lower.

Scalability remains a critical challenge for RNG as a feedstock for hydrogen production. The availability of RNG is constrained by the finite supply of organic waste streams and the geographic dispersion of feedstock sources. Landfills and wastewater treatment plants are concentrated near urban areas, while agricultural waste is more rural. Anaerobic digestion facilities require significant capital investment and operational expertise, limiting rapid deployment. Current RNG production volumes are a fraction of global natural gas demand, and even with aggressive expansion, RNG is unlikely to fully replace fossil natural gas for hydrogen production. However, it can play a complementary role in decarbonizing hydrogen in regions with abundant organic waste resources.

Policy incentives are essential to accelerate RNG adoption in hydrogen production. Governments have introduced renewable fuel standards, tax credits, and low-carbon hydrogen subsidies to improve the economics of RNG-based SMR. The U.S. Renewable Fuel Standard and California’s Low Carbon Fuel Standard provide credits for RNG use, while the European Union’s Renewable Energy Directive II includes RNG in its sustainability criteria. Certification schemes like the International Sustainability and Carbon Certification (ISCC) ensure RNG meets environmental and social standards, enabling cross-border trade. These mechanisms help bridge the cost gap between RNG and conventional natural gas, though long-term policy certainty is needed to attract investment.

Infrastructure requirements for RNG integration into hydrogen production include gas upgrading, pipeline injection, and purification systems. Raw biogas from landfills or digesters contains impurities like CO2, hydrogen sulfide, and moisture, requiring cleaning to meet pipeline standards. Upgrading facilities must be colocated with feedstock sources to minimize transportation costs. Pipeline networks need modifications to handle intermittent RNG supply, and hydrogen producers must adapt SMR plants to accommodate variable feedstock composition. Co-locating RNG production with hydrogen facilities can reduce infrastructure hurdles, as seen in several pilot projects.

Case studies demonstrate the feasibility of RNG-to-hydrogen projects. In California, the AltAir Paramount facility uses landfill-derived RNG to produce renewable hydrogen for refining and mobility applications. The project leverages state incentives and delivers hydrogen with a carbon intensity 60% lower than conventional SMR. In Germany, the HyFlexPower project integrates biogas from agricultural waste into a hydrogen production and power generation system, showcasing RNG’s role in sector coupling. Japan’s Tokyo Gas has piloted a micro-SMR plant running on sewage biogas, highlighting urban waste as a localized feedstock. These examples illustrate technical viability but also reveal challenges like feedstock consistency and regulatory complexity.

The economic competitiveness of RNG-based hydrogen depends on regional factors. Areas with high organic waste availability, supportive policies, and carbon pricing mechanisms are more likely to adopt RNG for SMR. In contrast, regions with cheap fossil gas and limited waste resources face higher barriers. Technological advancements in biogas upgrading and SMR efficiency could further improve RNG’s cost position, but economies of scale are limited by feedstock dispersion.

Environmental co-benefits add value to RNG-based hydrogen beyond carbon reduction. Landfill gas capture mitigates local air pollution, while anaerobic digestion reduces agricultural runoff and odors. These ancillary benefits can justify higher costs in certain contexts but are often excluded from market pricing mechanisms. Life cycle assessments must account for these factors to avoid underestimating RNG’s net positive impact.

In summary, RNG presents a viable but constrained pathway for low-carbon hydrogen production via SMR. Its carbon footprint advantage over conventional natural gas is clear, particularly when accounting for avoided methane emissions. However, feedstock limitations and infrastructure needs restrict its scalability as a standalone solution. Policy support and certification schemes are critical enablers, while case studies prove technical feasibility in niche applications. For RNG to meaningfully contribute to decarbonized hydrogen, it must be part of a diversified feedstock strategy alongside electrolysis and other low-carbon methods. Continued innovation in waste-to-energy systems and cross-sector collaboration will determine its long-term role in the hydrogen economy.