In France, cleantech startup SUBLIME Energie, a spin-off from Mines Paris–PSL, has officially inaugurated its biogas liquefaction demonstrator “Charlie,” the world’s first system capable of liquefying raw biogas directly on the farm, in Plélo, Côtes-d’Armor, Brittany.
For the first time, on-farm anaerobic digestion (AD) can produce a renewable fuel without relying on a gas grid infrastructure. By densifying and enabling the transport of biogas produced on-site—using a model inspired by the traditional milk collection system—the startup is deploying a decentralized industrial model.
In this system, biogas is converted into liquefied biomethane (bioLNG) for heavy-duty mobility, and the biogenic carbon dioxide (bioCO2), a co-product of biogas production, replaces fossil-derived carbon dioxide (CO2) across a range of agricultural and industrial applications.
With this demonstrator, SUBLIME Energie is scaling up to unlock the full value of fragmented agricultural resources, turning them into renewable energy and bioCO2.
Overcoming structural barriers in AD
Today, a significant share of farms around Europe and elsewhere remains excluded from biomethane injection. Limited production volumes, distance from gas grids, and high capital expenditure barriers continue to hinder the sector’s development.
SUBLIME Energie introduces a paradigm shift inspired by a simple and proven model: “the hub and spoke milk run.” Biogas produced on farms is liquefied, then collected locally and transported to centralized hubs for purification and commercialization.
This approach enables smaller or remote farms to participate in renewable fuel production, while bypassing infrastructure constraints tied to gas networks.
It also offers a transition pathway for existing cogeneration-based AD units nearing the end of their contracts, extending asset lifespan and improving profitability.
A technological breakthrough
At the core of the solution is a patented process that liquefies biogas directly on the farm, increasing its energy density and enabling off-grid transport.
SUBLIME Energie, a spin-off from Mines Paris–PSL, has developed an innovative on-farm biogas liquefaction technology that turns raw biogas, which contains methane (CH4) and CO2, into liquid biomethane (bioLNG) and liquid biogenic carbon dioxide (bioLCO2).
The company has patented a unique process that solves the technical constraints associated with the crystallisation (freezing) of carbon dioxide in the gas blend during cooling by using a carrier agent that changes its physical characteristics.
After a successful initial proof of concept in 2020, the company developed a demonstrator at Centre Énergie Environnement Procédés (CEEP) to validate liquefaction and separation of methane and carbon dioxide at a representative flow rate.
The liquefied raw biogas is then transported to centralized facilities, where cryogenic distillation separates the two liquefied gases into bioLNG and bioLCO2, respectively.
Integrated demonstrator
The “Charlie” demonstrator represents the final R&D milestone, integrating all technological building blocks on a single site under real operating conditions.
Installed at the Gazéa farm—one of Brittany’s pioneers in anaerobic digestion—Charlie processes biogas produced on-site, with an annual capacity of approximately 180 tonnes of bioLNG and 330 tonnes of bioLCO2.
Initial production will begin this year following commissioning and testing phases.
With Charlie, we will demonstrate that it is possible to overcome the historical limitations of anaerobic digestion. By liquefying biogas directly on the farm, we enable an off-grid model capable of unlocking large-scale value from a fragmented agricultural resource, said Bruno Adhémar, Founder and CEO of SUBLIME Energie.
Beyond technological performance, the project contributes to a broader transformation of energy systems. Upstream, anaerobic digestion reduces greenhouse gas (GHG) emissions from livestock waste and partially replaces the use of fossil-based fertilisers.
Downstream, bioLNG provides a low-carbon alternative to diesel for heavy-duty vehicles (HDVs), reducing GHG emissions by up to 85 percent.
BioLNG is also relevant for agricultural and maritime applications, where electrification remains challenging while bioCO2 valorization replaces fossil CO2 in sectors such as agriculture and the food industry.
A lever for energy sovereignty and farm income
Due to a lack of gas grid access, a significant share of Europe’s biomethane potential remains untapped. This resource, estimated in France alone to be 26 TWh by 2050, represents a strategic opportunity.
SUBLIME Energie aims to capture part of this potential by producing renewable gases locally.
The model is based on purchasing raw biogas from farmers, providing them with a stable additional revenue stream without requiring upfront investment in upgrading infrastructure. Farmers are also welcome to participate in project ownership if they choose.
There is no future for agriculture in Brittany without livestock farming. Yet the future of livestock farming depends on the democratization of biogas production and the support of this production. SUBLIME Energie’s model is a concrete solution to help livestock farms adapt, said Alain Guillaume, farmer, founder of Gazéa and of the French Association of Methanizing Farmers.
Industrial roadmap underway
With “Charlie,” SUBLIME Energie completes its final technological validation phase and enters industrial deployment. The company is already preparing its next project, “Delta,” which will connect around ten farms to a shared processing hub in Côtes-d’Armor.
This first commercial-scale unit is expected to be commissioned by 2028. Beyond that, SUBLIME Energie aims for rapid deployment across France and Europe, with the ambition to structure a new decentralized renewable gas industry.
