How to make bio-LNG?
Bio-LNG is liquefied methane (CH4) with a temperature below -150 degrees Celcius. The methane comes from biogas, which is produced by the anaerobic digestion of organic waste. This biogas must be treated to separate the methane from the carbon dioxide (CO2) and some critical contaminants. This step is called upgrading or gas treatment. It is a complex step as the methane purity must be very high before the methane can be liquefied.
Protecting the environment
As both carbon dioxide and methane are greenhouse gases, it is important for the environment as well as the business case that these gases are not released into the air during production of bio-LNG. A closed system which ensures that 100% of available methane from the biogas is converted into bio-LNG and also captures the CO2, not only results in a higher yield, it also protects the environment.
Importance of differences between biogas and natural gas
The difference between (fossil) LNG and bio-LNG is that bio-LNG is made from biogas while LNG is made from natural gas. It is important to acknowledge that technology for large-scale LNG production cannot be used for small-scale, decentralized production of bio-LNG. Therefore, Nordsol has reinvented the process of making LNG by carefully considering the key differences between natural gas and biogas:
- Required capacity of the installations
- Fluctuations in biogas composition and flow
- Complexity of the biogas composition
- Importance of energy management for economic viability
The result is a compact, highly integrated system of biogas treating and liquefaction that makes small-scale bio-LNG production economically viable.
Setting up a bio-LNG plant
Four distinct steps are necessary for a profitable plant. Building a bio-LNG plant becomes attractive starting from about 500 Nm3/h of raw biogas and requires between 18-30 months from idea until first bio-LNG.
The plant must have competitive value for the biogas producer. This needs to be proven in a high-level business case. This phase also defines the form of cooperation.
Create a basis of design with sufficient detail and cost estimates for a Financial Investment Decision (FID). This is also the start of the permitting process.
Engineering, Procurement & Construction. The installation is pre-fabricated in the factory, reducing the time of construction onsite. This phase also includes commissioning and start-up.
Operational phase including Nordsol operational support. Full bio-LNG and bio-CO2 production.
In the first phase, the feasibility and economic attractiveness of bio-LNG production in the specific situation is determined. Considerations include:
- Amount and composition of the biogas
- Valuation of the bio-LNG
- Carbon Intensity (CI) and Carbon Capture Utilization (CCU) calculations
- Available physical space
- Location type (agricultural, industrial, municipal)
- And more
In this phase, the form of cooperation between the biogas producer, bio-LNG offtaker and Nordsol is also defined.