Methanol is a simple alcohol that exists at room temperature as a colorless, highly volatile, and flammable liquid. Its chemical formula is CH3OH. Methanol has been transported worldwide for over 100 years and is also one of the five most-traded chemicals. The chemical also plays an important role in the hydrogen economy.
Methanol can be used as an energy carrier for hydrogen storage and transportation. In liquid form, the chemical is easier to transport than gaseous hydrogen and can utilize existing infrastructure for liquid fuels. It can also be used to generate electricity indirect methanol fuel cells.
The Different Types of Production (© Bureau Veritas Marine & Offshore)
Similar to hydrogen, the derivative is assigned a specific color depending on the production method.
- Braun: Coal-Fired Power Generation
- Gray: Produced from natural gas (currently the most common method)
- Blue: Production with carbon capture and storage (CCS)
- Green: Produced from biomass (bio-methanol) or from green hydrogen and CO₂ (e-methanol)
Manufacturing
Production via CO₂ capture and hydrogen (also known as“power-to-methanol”) involves four steps:
1. Capturing CO₂ from the ambient air (Direct Air Capture, DAC) or from industrial exhaust gases (Carbon Capture and Utilization, CCU).
2. Hydrogen production, e .g., through electrolysis, ideally using renewable electricity.
3. Synthesis of CO₂ and H₂ under pressure and heat, using a catalyst. The chemical reaction is: CO₂ + 3H₂ → CH₃OH + H₂O
4. Purification and distillation of the product.
In comparison, the conventional process involves:
1. Conversion of natural gas to synthesis gas
2. Catalytic reaction
3. Distillation and purification
Recovery
Reforming processes can release the hydrogen bound in methanol. This recovery takes place as follows:
1. Steam reforming: Methanol is mixed with steam at high temperatures (200–300°C). A catalyst, often copper-based, is used in this process.
2. Chemical reaction: Methanol and water vapor react to form carbon dioxide and hydrogen: CH₃OH + H₂O → CO₂ + 3H₂
3. Purification: The hydrogen produced in the previous step is separated from CO₂ and other byproducts.
4. Application: The purified hydrogen can now be used in fuel cells or for other purposes.
Advantages and Disadvantages of Methanol
Advantages
- Easy handling and transportation using existing infrastructure (tankers, pipelines, gas stations)
- High energy density in liquid form at room temperature (no cooling or compression required)
- Decades of experience in industrial handling and global transportation
- Versatile applications: directly as a fuel, in fuel cells, or for hydrogen recovery
- Relatively stable storage over extended periods of time
Disadvantages
- Can be very dangerous and toxic if handled carelessly
- Energy losses during production (power-to-methanol) and during hydrogen recovery
- An external source of CO₂ is required for the production of green methanol
- Corrosive properties require special materials for tanks and pipes
- CO₂ emissions during production; at most, carbon-neutral on a net basis
Video
This video from the OTH Regensburg Hydrogen Atlas projectillustrates the basic principle of methanol synthesis.
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