• Germany advanced RED III transposition last week, introducing explicit quotas for RFNBO (Renewable Fuels of Non-Biological Origin) for the first time
• Siemens, Atmen, and TURN2X have built the first end-to-end model for RED III-ready renewable gas production at TURN2X's commercial e-methane plant in Miajadas, Spain
• The Miajadas plant is fully operational, with 100 percent of its output sold under long-term offtake agreements, proof that green gas can be produced, certified, and delivered at a commercial scale today.

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(Munich, March 10, 2026)  Last week, Germany took a significant step toward closing remaining gaps in renewable fuel regulation. The Bundestag held the first reading of the Second Law on the Development of the Greenhouse Gas Reduction Quota, which will transpose RED III into national law and, for the first time, introduce explicit quotas for green hydrogen and e-fuels in the transport sector.

While most of Europe works toward RED III compliance, industrial offtakers are already demanding certified molecules as regulatory deadlines near. Siemens, Atmen, and TURN2X, all based in Munich, have developed the first end-to-end model for RED III-ready renewable gas production, from automated plant operations to certified product delivery. The plant of the future is already running at TURN2X's first commercial e-methane plant in Miajadas, Spain.

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TURN2X produces climate-neutral e-methane by combining green hydrogen with biogenic CO₂. The company plans to scale this model across Europe, aiming to cover 10 percent of Germany’s gas demand by 2031. Miajadas demonstrates the commercial viability of this pathway, with 100 percent of its renewable gas output sold under long-term off-take agreements. 

Intelligent operation and an ecosystem approach by Siemens

Siemens provides the industrial backbone for this model, including advanced automation systems, digital twin technology for remote plant operation, and standardised, secure deployment of future facilities.

Siemens adopts an ecosystem approach, collaborating with leading partners such as Atmen rather than developing every component in-house. “This is exactly how we at Siemens want to go forward in renewable energies,” says Philipp Glaser, Siemens Digital Industries. “We want to partner with the best solutions so our customers get innovation, technology, and speed of implementation.”

The data infrastructure layer provided by Atmen

Atmen, a regulatory technology company, provides the certification data layer. At Miajadas, this enabled the site to reach full RFNBO certification, making automated compliance part of day-to-day operations.

“Certification isn’t a nice-to-have; it’s market access and business case realization,” says Flore de Durfort, CEO of Atmen. “Our platform turns operational data into verifiable, auditable proof that keeps production continuously certification-ready so that renewable fuel producers can scale with confidence.”

The plant of the future, run by TURN2X

For TURN2X, combining Siemens’ industrial technology with Atmen’s compliance layer creates a blueprint for rapid, reliable expansion.

“Scaling across Europe brings two challenges: maintaining operational excellence and meeting increasingly complex certification requirements for renewable fuels,” says Dr.  Dominik Schollenberger, CTO of TURN2X. “The Miajadas plant shows that when intelligent operations and built-in compliance come together, e-methane can scale with the reliability our customers expect.”

The three companies share a single goal: scaling green energy production with intelligence, trust, and speed.

The plant of the future isn’t a vision. It’s running today in Miajadas.

About TURN2X

TURN2X develops and operates projects using its proprietary technology to produce e-methane by combining biogenic CO₂ with green hydrogen. The company focuses on scalable, infrastructure-ready renewable gas solutions that support industrial decarbonization and energy security.

About Siemens 

Siemens AG (Berlin and Munich) is a leading technology company focused on industry, infrastructure, mobility, and healthcare. The company’s purpose is to create technology that transforms everyday life for everyone. By combining the real and the digital worlds, Siemens empowers customers to accelerate their digital and sustainability transformations, making factories more efficient, cities more livable, and transportation more sustainable. A leader in industrial AI, Siemens leverages its deep domain know-how to apply AI – including generative AI – to real-world applications, making AI accessible and impactful for customers across diverse industries. Siemens also owns a majority stake in the publicly listed company Siemens Healthineers, a leading global medical technology provider pioneering breakthroughs in healthcare. For everyone. Everywhere. Sustainably. In fiscal 2024, which ended on September 30, 2024, the Siemens Group generated revenue of €75.9 billion and net income of €9.0 billion. As of September 30, 2024, the company employed around 312,000 people worldwide on the basis of continuing operations. Further information is available on the Internet at www.siemens.com.

About Atmen

Atmen (atmen.co) is a regulatory technology company providing the data infrastructure that powers trusted certification of industrial products. Atmen focuses on automating certification and enabling large-scale, verifiable supply chain transparency across energy-intensive industries. 

Founded in January 2023 by energy and regulation experts Flore de Durfort, Quentin Cangelosi, and Erika Degoute, Atmen has raised €6.3M to date to build technology that certifies industrial goods, starting with renewable gases. 

Headquartered in Munich, the company's platform is deployed across industrial sites in 9 countries, automating certification workflows and enabling verifiable proof of product attributes throughout the supply chain.

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At an estuary, freshwater from a river or stream meets saltwater from the open sea. Two flows with different origins and properties come together in the same body of water.

Once they mix, it's no longer about following individual drops, but understanding what each flow contributes.

Something similar happens in renewable fuel supply chains. Renewable and fossil fuels can share pipelines, storage facilities, and production infrastructure. 

So how can operators keep track of renewable inputs, their quantities, and their sustainability attributes when different sources share the same system?

That's where chain of custody comes in, a framework intended for tracking materials and their associated characteristics throughout the supply chain. 

One of its models is particularly relevant to renewable fuels: mass balance.

Four ways to track sustainability attributes

Not every supply chain tracks sustainability characteristics in the same way. Some models require certified materials to remain physically separate, while others allow greater flexibility.

ISO 22095 provides a general framework for chain of custody across industries. Four commonly discussed models help illustrate the differences:

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• Identity preserved: Material from one identified certified source remains separate throughout the supply chain. Its origin can be traced back to that particular source.
• Segregation: Certified materials from different sources may be combined, but they remain physically separate from non-certified materials.
• Mass balance: Materials with different sustainability characteristics can share a production, storage, or transport system under defined conditions. Their quantities and associated attributes are tracked through controlled accounting.
• Book and claim: Sustainability certificates or credits can be transferred separately from the physical product, without requiring the same connection between the buyer and the material flow.

Mass balance occupies a middle ground, offering greater flexibility than identity preservation or segregation while maintaining a connection between sustainability attributes and physical material flows.

This distinction is particularly relevant when renewable and fossil fuels share infrastructure.

So, what exactly is mass balance?

Mass balance is a chain-of-custody model that lets materials with different sustainability characteristics share a production, storage, or transport system while tracking the quantities and attributes associated with its inputs and outputs.

Think of a storage facility receiving two deliveries of a compatible fuel: one certified as renewable and the other fossil. Under the relevant conditions, both can enter a shared tank.

Once mixed, the point is no longer to identify which molecules came from each delivery. But how can the operator demonstrate how much fuel entered the system, which sustainability characteristics accompanied it, and how those characteristics are assigned to the fuel leaving it?

In practice, three principles keep the system accountable:

1. The quantities must add up. Operators cannot assign more certified output than their eligible inputs support, taking applicable conversion factors and losses into account.
2. The system has defined boundaries. Materials and their attributes must be tracked within an eligible facility, storage location, or interconnected infrastructure, rather than transferred freely between unrelated sites.
3. The records must reconcile. Inputs, outputs, and remaining eligible quantities must be accounted for over a defined balancing period, in accordance with applicable regulatory and certification requirements.

These principles are reflected in the EU's Implementing Regulation 2022/996, which establishes requirements for applying mass balance in renewable fuel supply chains.

Together, these controls allow materials to share infrastructure without losing accountability for their sustainability attributes.

Why mass balance matters for renewable fuels

Beyond tracking sustainability attributes, mass balance has practical implications for how renewable fuels are produced, distributed, and certified.

Making use of existing infrastructure

Building dedicated pipelines, storage tanks, and production facilities for renewable fuels would introduce significant logistical challenges and additional investment.

Mass balance offers an alternative. Where the applicable rules permit, renewable and fossil materials can share infrastructure while their quantities and sustainability characteristics remain accounted for.

Biomethane illustrates this well. According to the 2026 European Biomethane Map by GIE and EBA, Europe has 1,974 biomethane production facilities, with at least 86% connected to the gas grid. 

Rather than requiring a separate network, biomethane can be injected into existing gas infrastructure alongside fossil natural gas.

Scaling renewable production gradually

Mass balance allows renewable materials to enter established supply chains without waiting for entire facilities to operate exclusively on renewable inputs.

Where permitted, a producer can start with a smaller share of eligible renewable material and increase it over time, while continuing to meet the relevant certification requirements. This flexibility supports the gradual expansion of renewable fuels through existing production and distribution systems.

Reducing the cost of physical separation

Keeping certified materials separate throughout production, storage, and transport can require dedicated equipment and logistics.

By allowing eligible materials to share facilities, mass balance can reduce some of these additional costs.

That doesn't necessarily make mass-balanced fuels cheaper, as savings depend on the infrastructure, production pathway, and certification requirements. But avoiding unnecessary physical separation can make the integration of renewable materials more feasible economically.

Making renewable fuels count under EU rules

For fuel suppliers, mass balance also has a regulatory function.

Under the EU Renewable Energy Directive, eligible renewable fuels must meet specific sustainability and greenhouse gas emissions-saving requirements to count towards relevant renewable energy targets.

Mass balance provides the chain-of-custody framework for maintaining and transferring the required information throughout the supply chain. A Proof of Sustainability (PoS) documents the relevant attributes of a certified fuel batch, supporting its recognition under applicable requirements.

For renewable hydrogen, this has direct implications. Under RED III (Article 22a), at least 42% of the hydrogen used in industry must be renewable fuel of non-biological origin (RFNBO) by 2030, rising to 60% by 2035. To count towards these targets, RFNBO hydrogen needs a PoS, which relies on mass balance.

This differs from a Guarantee of Origin (GO), which serves a separate purpose and cannot, on its own, replace the sustainability evidence required for renewable fuel certification.

Mass balance therefore helps ensure that renewable fuel quantities retain the documented attributes needed for recognition under the relevant rules.

Beyond the shared tank

For an estuary, the meeting of the two streams is just a stop within a broader journey. The same is true of renewable fuels: once feedstocks enter a shared system, they continue to move, change hands, and, at times, undergo further transformation processes.

Tracking materials is only one aspect of the task. Their sustainability attributes, allocations, and supporting documentation must remain consistent and verifiable throughout the supply chain.

Through Atmen Automate, Atmen provides ongoing support to operators and traders, connecting operational data, maintaining mass balances, and keeping records traceable and ready for certification and audits.

Experience how Atmen Automate can help.

Talk to the team

‍Frequently Asked Questions

Can renewable and fossil fuels share the same infrastructure?

Yes, where the applicable regulations and certification rules permit it. Mass balance allows eligible materials with different sustainability characteristics to share certain facilities while their quantities and associated attributes are accounted for separately.

What is the difference between mass balance and book and claim?

Mass balance maintains a connection between sustainability attributes and physical material flows within a defined system. Book and claim allows certificates or credits to be transferred independently of the physical product, subject to the rules of the relevant scheme.

For renewable fuels counted towards EU targets, however, there is no choice between the two. Article 30(1) of the Renewable Energy Directive requires economic operators to use a mass balance system to show that the sustainability and greenhouse gas emissions-saving criteria have been met. Book and claim instruments, such as Guarantees of Origin, cannot be used for this purpose.

Does mass balance automatically make a fuel certified as renewable?

No. Mass balance is a chain-of-custody method, not a certification in itself. A fuel must still meet the applicable eligibility, sustainability, and greenhouse gas emissions-saving requirements, with the necessary supporting evidence and verification.

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