Naturgy, Spain’s largest gas distributor, and technology firm Greene have launched a pilot plant in Elche, Alicante, to convert non-recyclable industrial and urban waste into grid-compatible renewable gas using a two-stage gasification and microbial conversion process. The Waste to Biomethane (W2BM) project targets dry, carbon-rich waste streams — plastics, textiles, and mixed residues — that cannot be processed through conventional anaerobic digestion and would otherwise go to landfill or incineration. If the technology proves stable and cost-competitive at scale, it could unlock a vast new feedstock pool for biomethane production, directly supporting the decarbonisation of gas networks and hard-to-electrify industrial demand.
Conventional biomethane relies on wet organic waste — agricultural residues, sewage sludge, food waste — broken down by bacteria in oxygen-free digesters. The W2BM route is fundamentally different: prepared waste is first gasified into syngas (a mixture of hydrogen, carbon monoxide, and carbon dioxide), then specialised microorganisms convert that syngas into methane. This biochemical methanation step operates at lower temperatures and pressures than catalytic alternatives, and the consortium targets a methane concentration above 95%, the threshold for injection into Spain’s existing gas grid without further upgrading.
For Naturgy, the stakes are strategic. The company has positioned biomethane as a cornerstone of its gas decarbonisation roadmap, particularly for industrial heat and heavy transport where electrification remains impractical. Through its distribution subsidiary Nedgia, Naturgy already connects renewable gas plants to the network; a technology that expands the feedstock base beyond wet organics would dramatically increase the theoretical potential for domestic biomethane supply. Greene brings over a decade of experience in pyrolysis, gasification, and waste valorisation, and the joint venture structure signals both parties view this as a commercial pathway, not just a research exercise.
The pilot phase is explicitly designed to de-risk the economics. Gasification of heterogeneous waste is technically demanding — feedstock variability, tar formation, and syngas cleaning have historically undermined project bankability. The microbial conversion step adds biological process stability questions: microorganism health, contamination risk, and long-term reactor performance under real-world conditions. Naturgy and Greene have not disclosed a timeline for an industrial-scale investment decision, but the industry will watch closely for data on capacity factor, operating expenditure, and the all-in levelised cost of the resulting biomethane.
Beyond the corporate balance sheets, W2BM illustrates a broader shift in European energy policy: waste is increasingly framed as a carbon resource rather than a disposal problem. The EU’s waste hierarchy, landfill diversion targets, and the upcoming revision of the Waste Framework Directive all create regulatory tailwinds for technologies that recover energy from residual waste streams. If gasification-biomethanation closes the loop on materials that mechanical recycling cannot handle, it could become a meaningful pillar of the circular carbon economy — provided the full lifecycle emissions, including avoided landfill methane and incineration CO₂, stack up credibly.
Read the full report at The Energy Post.