[Hatem]

From my professional perspective, the cost of biogas upgrading for a plant producing poor-quality biogas—characterized by high levels of impurities such as 6,000 ppm H2S, elevated moisture, or siloxanes—can be substantial, driven by the need for robust pretreatment and upgrading systems to meet stringent biomethane standards. Capital expenditure (CAPEX) encompasses equipment like biological or chemical H2S scrubbers, CO2 removal units (e.g., membrane separation or amine scrubbing), dehumidifiers, and siloxane filters, with costs for a 1,000 Nm³/h plant ranging from $500,000 to $2 million, often leaning toward $1–1.5 million for low-quality biogas due to larger, more complex systems, plus 20–30% for installation, engineering, and permitting. Operating expenditure (OPEX) includes frequent replacement of consumables (e.g., activated carbon at $2–$5/kg or caustic chemicals at $0.5–$1/kg), energy for pumps and aeration, maintenance, and hazardous waste disposal, totaling $50,000–$200,000/year, with high H2S potentially driving costs toward $100,000 annually for chemicals ($40,000), energy ($30,000), maintenance ($20,000), and waste handling ($10,000). These elevated costs, compared to $300,000–$500,000 CAPEX and $20,000–$50,000/year OPEX for cleaner biogas, underscore the importance of tailoring system design to biogas quality to optimize long-term economics.

To sidestep the costly challenges of upgrading poor-quality biogas with high H2S (e.g., 6,000 ppm), moisture, or siloxanes, I advocate a strategic approach that leverages AI modeling alongside proactive process optimization for a cleaner, more cost-effective operation. From my perspective, integrating AI-driven predictive models can transform biogas pretreatment by forecasting impurity levels based on feedstock composition, digester conditions, and operational data, enabling preemptive adjustments. For instance, AI can analyze historical and real-time data (e.g., pH, temperature, sulfur content) to optimize anaerobic digestion, minimizing H2S production at the source by recommending ideal feedstock blends or process parameters—say, avoiding sulfur-rich inputs like manure or protein-heavy food waste.

[Natalia Bourenane]

Hatem, thank you very much for this detailed answer and some numbers. Will your numbers be more for Europe or North America? Or will they ring true anywhere?

[Soheil]

The cost of biogas upgrading is highly dependent on the project’s scale and the specific technology employed. Conventional upgrading technologies, such as water scrubbing or pressure swing adsorption, typically have higher capital and operating costs. In contrast, newer technologies are becoming more cost-effective due to performance improvements, the ability to operate under ambient conditions, and reduced energy requirements. As innovation continues, the cost of biogas upgrading is trending downward.

[Natalia Bourenane]

Soheil, thank you for the answer. What about your Hydron technology? How do costs compare to other technologies?

[Saeid Tajbakhsh]

Thank you for the question. Our biogas upgrading platform is designed to be both cost-effective and operationally flexible. Compared to available biogas upgrading systems, our approach offers up to 50% lower capital and operating costs. These cost advantages are due to the system operating under mild conditions, which significantly simplifies the biogas upgrading platform and reduces operating requirements, resulting in lower CAPEX and OPEX.

[Nikolas]

As stated in the other replies, upgrading costs depend on key parameters, such as the gas flow, the concentration of contaminants to clean your biogas (H2S, VOCs, Siloxanes) and the technology you choose (ie. membrane upgrading, amines, PSA). The size of the project would naturally also impact CapEx and OpEx. Depending on the project, gas cleanup and upgrading could cost anything from $1M – $15M, so the answer here is ‘it depends on your project’.

Are you debating between producing electricity vs RNG?

[Natalia Bourenane]

Nikolas, thank you for the range, 1-15M is quite a stretch, honestly. As for electricity vs upgrading, is it always about the costs?

[Nikolas]

The difference has to do with the project conditions – For example a 110 scfm project with 100ppmv H2S injecting in the grid would have a CapEx closer to $1.5M. A 1,000 scfm with 600ppm H2S and VOCs would be closer to >$8M.

As for electricty vs RNG, the CapEx might be lower to produce electricity but the incentives are not as strong. Renewable electricity can come from other sources (i.e. solar, wind), which lowers the selling price. RNG can be injected in the grid and used as fuel, and has strong incentives, which makes RNG projects more desirable, in my view.