Green methane, often referred to as e-methane, is produced through a two-stage process that combines renewable electricity and captured carbon dioxide.
The production process leverages technology based on the Power to Hydrogen principle, followed by a methanation step.
The Two Stages of Green Methane Production
According to grtgaz.com, the production of e-methane involves these key steps:
-
Green Hydrogen Production:
- Renewable electricity (such as solar or wind power) is used.
- This electricity powers an electrolysis process.
- Electrolysis splits water (H₂O) molecules into hydrogen (H₂) and oxygen (O₂). The hydrogen produced using renewable electricity is considered "green hydrogen."
-
Anaerobic Digestion (Methanation):
- This stage involves a reaction between the green hydrogen produced in the first stage and recycled carbon dioxide (CO₂).
- The reaction takes place in the presence of a catalyst, which helps speed up the process.
- This reaction is a form of methanation, where H₂ and CO₂ combine to form methane (CH₄) and water (H₂O). This specific process involving H₂ and CO₂ is often called biological or catalytic methanation, not traditional anaerobic digestion (which breaks down organic matter). The reference uses "Anaerobic digestion itself takes place, i.e. the reaction of renewable hydrogen with recycled CO2". While traditionally anaerobic digestion is different, in this specific context from the reference, it describes the methanation step.
- The resulting methane is considered "green" because it utilizes renewable hydrogen and captured CO₂.
Here's a simple breakdown:
| Stage | Input | Process | Output | Key Requirement |
|---|---|---|---|---|
| 1. Hydrogen Production | Renewable Electricity, Water | Electrolysis (Power to Hydrogen) | Green Hydrogen (H₂), Oxygen (O₂) | Renewable Power |
| 2. Methanation | Green Hydrogen (H₂), Recycled CO₂ | Reaction with Catalyst (referred to as Anaerobic Digestion in the source context) | Green Methane (CH₄), Water (H₂O) | Catalyst, Recycled CO₂ |
This method effectively converts renewable electrical energy and captured carbon into a synthetic natural gas that can be stored and transported using existing gas infrastructure.
