Biogas Partial Purification for Centralized RNG Upgrading

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Solution Overview

Problem

Biogas upgrading to renewable natural gas (RNG) is economically infeasible for small-scale producers due to high capital investment costs, and existing methods do not efficiently address issues like corrosion and safety related to contaminants like H2S and CO2.

Innovation Solution

A method involving partial purification of biogas at the source before transport to a centralized facility, using stationary systems to remove H2O, H2S, and CO2, followed by further purification to produce RNG, leveraging economies of scale.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If biogas is fully upgraded to RNG at a centralized facility, then the calorific value and purity are improved, but the capital investment cost increases significantly

Engineering Contradiction:

Improvebiogas purityVSAvoidcapital investment cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The biogas upgrading process is divided into two segments: (1) partial purification at distributed pre-processing sites removing H2S, H2O, and some CO2, and (2) final upgrading to RNG at a centralized facility. This segmentation allows small producers to perform initial purification locally while benefiting from the economies of scale at the centralized facility, reducing overall capital investment requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Pre-processing sites perform preliminary purification of biogas by removing H2S, H2O, and some CO2 before transport to the centralized facility. This preliminary action reduces the burden on the centralized facility and improves the efficiency of subsequent upgrading processes, making the overall system more cost-effective.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If biogas is transported without partial purification, then transport infrastructure is simpler, but corrosion and safety issues worsen due to contaminants like H2S and CO2

Engineering Contradiction:

Improvetransport infrastructureVSAvoidcorrosion and safety issues

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If CO2 is removed during transport preparation, then more methane can be transported per unit volume, but the purification process complexity increases

Engineering Contradiction:

Improvemethane transport capacityVSAvoidpurification process

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

Pre-processing sites perform partial CO2 removal rather than complete removal. This partial action increases methane concentration and transport capacity while avoiding the complexity and cost of complete CO2 removal, which is better suited for the centralized facility's larger-scale equipment.

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Reduces costs and improves efficiency by allowing smaller producers to benefit from economies of scale, enhances safety, and optimizes methane transport by reducing contaminants, thus making RNG production viable for small-scale operations.

Implementation Method 1

removing one or more components from the first biogas to produce a first partially purified biogas, said one or more components comprising hydrogen sulfide, carbon dioxide, or a combination thereof, said one or more components removed using at least one stationary purification system

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

When the partial purification includes removing contaminates such as H2O and H2S

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS20250352943A1Method and system for upgrading biogas

Publication Date: 2025.11.20 IOGEN CORPORATION

AI summary

A method for providing renewable natural gas (RNG) includes removing hydrogen sulfide and/or carbon dioxide from biogas to provide partially purified biogas, which may be stored in a mobile storage tank. The partially purified biogas is transported to a biogas upgrading facility, at least partially by truck, rail, or ship. At the biogas upgrading facility, the partially purified biogas is further purified to provide the RNG, which can be injected into a distribution system (e.g., natural gas grid) and/or provided for use in transportation.