Liquefied Natural Gas (LNG) is a subject that has been discussed so often for many months. LNG tankers will be used to import liquid natural gas to Germany and thus cover part of the national gas demand. Conventional, i.e. fossil natural gas, is used for liquefaction. Imported liquefied gas is filled into special storage tanks, regasified and distributed through the natural gas pipeline network. Alternatively, LNG can be transported e.g. by ship, rail and tanker to other locations and used there.

The liquefaction of biomethane instead of fossil natural gas produces bio-LNG. Sustainable LNG alternatives are mainly required for heavy goods vehicles to reduce emissions from fossil fuels. Bio-LNG thus helps green transport. Compared to diesel, bio-LNG makes it possible to reduce nitrogen oxide emissions by 90 percent and fine dust by 99 percent. Using biomethane and energy-efficient liquefaction processes significantly reduces the CO2 footprint of trucks. Depending on the material used as an input for producing biomethane, CO2 emissions are reduced by 100 percent compared to diesel engine trucks.

Bio-LNG production

Bio-LNG is produced from biomethane, which is biogas processed to natural gas quality. Biogas is generated from renewable raw materials, such as manure such as dung or the fermentation of biowaste.

The chemical characteristics of LNG and Bio-LNG are comparable. The same technical processes can be applied for liquefaction. During the process in liquefaction facilities, the gas is cooled to approx. –160 degrees Celsius, changing from gaseous to liquid aggregate state. In this process, the volume decreases by a factor of 600 and offers perfect transport possibilities.

Natural gas or biomethane can be liquefied at sites near gas pipelines. Small-scale liquefaction plants can be installed at biogas sites equipped with biogas processing technology. The liquid bio-LNG is stored in storage tanks until collection.

Possible uses of bio-LNG

Bio-LNG offers wide range of applications. On the one hand, it can supply and operate decentralized CHP plants and, on the other hand, as a source of process heat in industries. Thanks to the excellent transport properties, sites without connection to the gas network can be supplied with gas. LNG can also be used for food refrigeration. To this end, evaporative cooling is converted into a usable deep cold temperature up to –40 degrees Celsius. However, bio-LNG is mainly used as fuel for heavy-duty, long-distance, and maritime transport.

The LNG filling station network in Germany is currently under development. There are currently approximately 150 filling stations in operation, primarily at high-traffic locations such as highways.

Why green LNG – what are the advantages?

• Bio-LNG offers users the significant advantage that during its use, CO2 emissions are much lower than when fossil-based fuels are used. As a result, bio-LNG users achieve a competitive advantage and underline their contribution to more sustainability in the transport sector.
• On the generation side, bio-LNG production offers new opportunities for biogas plant operators to liquefy the produced raw biogas directly after it has been processed to biomethane. Bio-LNG production is thus an alternative to biomethane injection into the gas network or a new option of energy marketing when the conversion of biogas into electricity is less economical. That creates new sales potentials for the numerous operators of the approximately 9,700 biogas plants in operation by the end of 2021.
• New lines of business are also emerging. Specialized companies are offering liquefaction services, thus creating opportunities for biomethane producers to generate and market bio-LNG. In the fuel market, bio-LNG from waste-derived biogas plants or NAWARO biogas plants that capture CO2 is much in demand.

Green LNG developments

Fossil-based LNG predominates nowadays. Current developments show that LNG production from renewable sources is increasing and can be a component of the transition to sustainable transportation.

For example, the mineral oil group Shell is building a bio-LNG plant in Cologne-Godorf Shell Energy and Chemicals Park. Initial work has already begun in February 2022. According to statements by the group, the plan is to annually produce up to 100,000 tons of a liquefied mixture of biomethane and natural gas with CO2-neutral properties, starting in the second half of 2023. After completion of the plant, all Shell LNG filling stations will be supplied with the final product. This amount will be enough to refuel up to 5,000 LNG trucks.

A joint venture of BALANCE Erneuerbare Energien and EnviTec Biogas is planning to build a liquefaction plant near Berlin. At this site, the BALANCE EnviTec Bio-LNG GmbH plans to further process biomethane generated in biogas plants into bio-LNG. Production is scheduled to start in 2024. The final product will be primarily used in the mobility sector, thus contributing to a greener long-distance and heavy-duty transport.

The opportunities offered by bio-LNG are manifold. Therefore, innovative players, as well as political players (with the further development of the policy framework) should open up the related potentials and exploit them for the sake of a sustainable future.

The authors work with greenValue GmbH. greenValue is a service provider in the sector of renewable energies with long-standing expertise and comprehensive references, among others in the field of project management.

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Source: 14 November 2022, www.greenvalue.de