Biogas Compression with Retained Carbon Dioxide

Solution Overview

Problem

Existing biogas purification processes for producing biomethane are energy-inefficient and costly, especially for smaller production sites, and require extensive removal of carbon dioxide, which is unnecessary and inefficient.

Innovation Solution

A process that compresses purified biogas with a significant amount of carbon dioxide (10-70 mol%) to form a compressed fuel suitable for combustion engines, bypassing the need for extensive carbon dioxide removal, using techniques like adsorption, chilling, and temperature swing adsorption to prepare a compressed fuel with a methane content of 30-90 mol% and carbon dioxide content of 10-65 mol%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon dioxide is removed from biogas to form biomethane, then the fuel quality is improved, but the energy efficiency and cost worsen due to intensive processing steps

Engineering Contradiction:

Improvefuel qualityVSAvoidenergy efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the essential contaminants (hydrogen sulphide, water, siloxanes) from biogas while retaining carbon dioxide, rather than removing all non-methane components. This selective extraction approach maintains sufficient fuel quality for combustion engines while avoiding the energy-intensive process of complete CO2 removal required for biomethane production

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of following the conventional approach of removing CO2 to produce biomethane, the patent inverts the strategy by accepting CO2 retention and compressing the purified biogas directly to high pressure (100-350 bara) for use as compressed natural gas (CNG). This inversion eliminates the need for energy-intensive CO2 removal while still producing a usable fuel

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If carbon dioxide is removed from biogas to form biomethane, then the fuel quality is improved, but the cost worsens due to intensive processing steps

Engineering Contradiction:

Improvefuel qualityVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts only the essential contaminants (hydrogen sulphide, water, siloxanes) from biogas while retaining carbon dioxide, rather than removing all non-methane components. This selective extraction approach maintains sufficient fuel quality for combustion engines while avoiding the energy-intensive process of complete CO2 removal required for biomethane production

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of following the conventional approach of removing CO2 to produce biomethane, the patent inverts the strategy by accepting CO2 retention and compressing the purified biogas directly to high pressure (100-350 bara) for use as compressed natural gas (CNG). This inversion eliminates the need for energy-intensive CO2 removal while still producing a usable fuel

Inventive Principle:

Principle #13The other way round (Inversion)

3Use of energy by moving object

If biogas is compressed with significant carbon dioxide content, then the energy efficiency is improved, but the suitability for combustion engines may worsen

Engineering Contradiction:

Improveenergy efficiencyVSAvoidcombustion engine suitability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies partial purification by removing only the most harmful contaminants (hydrogen sulphide, water, siloxanes) while retaining carbon dioxide, rather than performing complete purification to biomethane standards. This partial action is sufficient for combustion engine operation while maintaining energy efficiency, as combustion engines can tolerate CO2 presence unlike other applications requiring ultra-pure biomethane

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

The process is more energy-efficient and cost-effective, reducing the number of processing steps and environmental impact while maintaining a suitable fuel for combustion engines, with lower emissions and higher energy density.

Implementation Method 1

using techniques like adsorption, chilling, and temperature swing adsorption to prepare a compressed fuel

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

using techniques like adsorption, chilling, and temperature swing adsorption to prepare a compressed fuel

Methodology Applied

Scientific EffectTemperature swing adsorption: Pressure Swing Adsorption

Implementation Method 3

compressing the purified biogas to a pressure of 100 - 350 bara to form a compressed fuel

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentEP4323478B1Compression of a biogas containing carbon dioxide, and use thereof in a combustion engine

Publication Date: 2025.10.22 POWERCRUMBS BV

Figure 1
Figure 2
Figure 3

AI summary

The invention is directed to a process of preparing a compressed fuel, to a compressed fuel, and to the use of a compressed fuel comprising methane and carbon dioxide. The process of the invention comprises - providing a biogas; - removing one or more components from the biogas to obtain a purified biogas, wherein the purified biogas has a methane content of 30 mol% or more and a carbon dioxide content of 10 mol% or more, and - compressing the purified biogas to a pressure of 70 bara or more to form a compressed fuel.