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Mantle8, the Grenoble France based natural hydrogen exploration company, has raised €31M in Series A funding to leverage its proprietary technology stack across a global exploration and drilling campaign targeting the first commercially exploitable reservoir of high-purity natural hydrogen. The round was led by Sandwater and includes Breakthrough Energy Ventures, Ecotechnologies 2 fund managed on behalf of the French government by Bpifrance, IP Group, Wind Capital and Calderion (an Audacia-backed investment platform).

This capital will be deployed during the next two years to fund the world’s most advanced natural hydrogen exploration and drilling campaign. Mantle8’s novel technology platform, which is tailored to identify commercially viable natural hydrogen reservoirs, will be employed across its global development pipeline to identify and rank the most promising opportunities. These sites will then be drilled to confirm natural hydrogen accumulations and to evaluate volume, purity, and reservoir quality in support of commercially viable, large-scale production.

Hydrogen is a crucial part of our future decarbonised industrial system; however, the importance of its role will depend on its price and origin. Mantle8’s novel technology for identifying commercially viable natural hydrogen reserves reduces exploration risk and cost, with economic models projecting production costs as low as €0.80/kg, significantly contributing to a much lower average cost of clean hydrogen supply. This will fundamentally change the hydrogen sector’s economics, unlocking a low-carbon source of sovereign energy supply for Europe as well as other geographies. By cooperating with partners focused on drilling and exploiting target reservoirs, the technology can be rolled out quickly and at scale.

“This raise reflects the growing conviction among leading clean tech investors that natural hydrogen is a resource worth pursuing at scale,” said Emmanuel Masini, Founder and CEO of Mantle8. “The existence of natural hydrogen is a well-established scientific fact; the challenge has been finding free gas accumulations of high-purity hydrogen that are commercially viable. I’m proud that we’ve built and patented an entire technology stack to answer this critical challenge, meeting the expectations of our existing shareholders” he continued. “The next steps are to identify the prospects in our pipeline that meet our commercial hurdles and drill them. I’m excited to welcome investors who have a long history of involvement in subsurface resources, sovereign investments and ecosystem building.”

“We built Sandwater to back exceptional founder teams with the technical depth and operational rigour to solve critical challenges and deliver solutions that lead to a better future”, said Tom Even Mortensen, Founder and Managing Partner of Sandwater. “Mantle8 is exactly that kind of company. Emmanuel and his team have built truly proprietary exploration technology, validated it in the field, and now have a clear plan to move into the commercial phase. Natural hydrogen sits at the intersection of energy transition and resource discovery, two areas where Europe must lead as it seeks energy sovereignty. This is a demanding challenge but with the potential to create a new clean energy source, which is what we need and why we see in Mantle8 the opportunity for outsized impact and return”

“Geologic hydrogen is one of the most surprising energy developments of the past decade, with the potential to play a significant role in the global energy mix,” said Carmichael Roberts of Breakthrough Energy Ventures. “The Mantle8 team has made impressive progress in advancing its rigorous, geology-driven approach to exploration, and the team continues to execute on targeting the first commercially exploitable reservoir of high-purity natural hydrogen.”

“Natural hydrogen represents a strategic opportunity for France and for Europe,” said Alexandre Wagner, Investment Director at Bpifrance Green Venture. “Mantle8 combines a proprietary exploration technology stack with a clear path to commercialization. Backing this company, aligns with our mandate to accelerate the energy transition through sovereign, low-carbon solutions that could be developed before the end of the decade.”

Mantle8’s Series A follows a period of significant momentum for Mantle8. In 2025, the company raised a €3.4M Seed Round led by Breakthrough Energy Ventures and went on to complete the world’s first 4D imaging of an active underground natural hydrogen system using HOREX® at its Hydrogeco project in the French Pyrenees. Earlier this year, Mantle8 received a €2.06M grant from the EU Just Transition Fund to industrialise its core exploration technologies.

This investment round brings total funding raised by Mantle8 to €37M (US$44M). “With this backing, we will work alongside industrial partners globally to move from exploration through to commercial development”, said Bart Markus, Mantle8’s chairman. “The next two years are about proving that the active hydrogen systems our technology has pinpointed can deliver sustained, commercially viable flow.”

 

About Mantle8

Mantle8 is a natural hydrogen exploration company founded in 2019 and headquartered in Grenoble, France. The company develops proprietary subsurface modelling and exploration technologies, including HOREX®, a multiphysics platform that produces 4D images of active underground hydrogen systems. Mantle8’s exploration framework, the Geological Trifecta, identifies reservoirs where an active hydrogen-generating source, continuous replenishment and
a sufficiently sealed reservoir converge. The company is backed by Breakthrough Energy Ventures, Sandwater, Ecotechnologies 2 fund – managed by Bpifrance on behalf of the French government as part of the France 2030 initiative, Kiko Ventures, Wind Capital and Calderion.

Visit mantle8.com to learn more.

 

About Breakthrough Energy Ventures

Breakthrough Energy Ventures is a purpose-built investment firm that partners with, launches, and scales global companies that are building an emissions-free global economy. We seek true breakthroughs and are committed to supporting these entrepreneurs and companies by bringing to bear a unique combination of technical, operational, market, and policy expertise.

Backed by many of the world’s top business leaders, companies, and investors, Breakthrough Energy Ventures has raised more than $3.5 billion in committed capital and partnered with more than 110 groundbreaking companies.

Breakthrough Energy Ventures is the venture capital arm of Breakthrough Energy, a global network of climate leaders committed to accelerating the world’s journey to a clean energy future. The organization funds breakthrough technologies, advocates for climate-smart policies, and mobilizes partners around the world to take effective action, accelerating progress at every stage.

Visit Breakthrough Energy Ventures to learn more.

 

About Sandwater

Sandwater invests in the commercialization of deep tech and impact-driven companies addressing critical challenges across energy, resource efficiency, robotics/AI, and health. We partner with exceptional founders, providing conviction, competence, and capital to help scale transformative solutions that create lasting impact.

Sandwater invests from late Seed through Series B across the Nordics and Northern Europe.

Visit sandwater.com to learn more.

 

About IP Group

IP Group is the most active UK based, early stage science and technology investor, developing and supporting some of the world’s most exciting businesses in healthtech, deeptech and cleantech. Including through Parkwalk, the UK’s largest growth EIS fund manager, the Group backs world-changing innovation emerging in leading universities and research institutions.

IP Group has a strong track record of success, having backed high-profile companies including Oxford Nanopore Technologies plc, Hinge Health, Featurespace, Ceres Power plc, Hysata, and Oxa.

IP Group is a long term backer of Mantle8, following on in this round, having previously invested under the brand of its Kiko Ventures platform.IP Group is UK headquartered and is listed on the Main Market of the London Stock Exchange under the code IPO.

Visit ipgroupplc.com to learn more.

 

About Wind Capital

Wind is an independent European venture firm founded in Paris by entrepreneurs. The firm invests in deeptech founders working on climate resilience and European technological sovereignty, through two funds: Wind II, a €130M Article 9 climate fund, and Technologies Souveraines, dedicated to defense and strategic autonomy.

Visit wind.capital to learn more.
 

About Calderion

Calderion is an industrial deep-tech fund dedicated to scaling next-generation fuel technologies, including low-carbon hydrogen, CO₂ capture, and synthetic fuels. Acting as a value chainarchitect, it deploys capital across the full industrial stack to build sovereign, decarbonized, and competitive value chains across Europe, enabling the transition to a post-fossil era. Driven by an industrial-first approach, Calderion combines capital with technological and industrial expertise to bring innovative technologies to market, transforming emerging innovations into industrial-scale products.
Calderion is backed by Audacia, an independent private equity firm with over 20 years of experience supporting strategic sectors. Listed on Euronext Growth Paris, Audacia is a leading player in the financing of innovation and industrial transformation.

Visit calderion.com | audacia.fr to learn more.

 

About Bpifrance and the Ecotechnologies 2 Fund

Bpifrance provides financing to businesses at every stage of their development, through loans, guarantees, and equity. Bpifrance supports them in their innovation and international expansion initiatives. Bpifrance also supports their export activities through a wide range of products. Consulting, university partnerships, networking, and acceleration programs for startups, SMEs, and mid-market companies are also part of the services offered to entrepreneurs.

Thanks to Bpifrance and its 50 regional offices, entrepreneurs have access to a local, dedicated, and effective point of contact to help them overcome their challenges.

With €300 million in government funding under the France 2030 initiative, the Ecotechnologies 2 fund is managed by Bpifrance Investissement. It invests amounts ranging from €2 million to €10 million, systematically seeking pari passu co-investments with private sector partners as part of a prudent investment strategy. It targets equity and quasi-equity transactions for minority stakes in innovative SMEs.

Visit bpifrance.fr to learn more.

 

About the France 2030 Investment Plan :

• Reflects a twofold ambition: to bring about lasting transformation in key sectors of our economy (healthcare, energy, automotive, aerospace, and space) through technological innovation, and to position France not merely as a player, but as a leader in the world of tomorrow. From basic research and the emergence of an idea to the production of a new product or service, France 2030 supports the entire innovation lifecycle through to industrialization.
• It is unprecedented in its scale: €54 billion will be invested to ensure that our businesses, universities, and research organizations fully succeed in their transitions within these strategic sectors. The goal is to enable them to respond competitively to the environmental and competitiveness challenges of the coming world, and to foster the future leaders of our sectors of excellence. France 2030 is defined by two cross-cutting objectives: to allocate 50% of its spending to decarbonizing the economy, and 50% to emerging, innovative actors, without any spending that is harmful to the environment (in accordance with the “Do No Significant Harm” principle).
• Is implemented collectively: designed and rolled out in consultation with economic, academic, local, and European stakeholders to determine its strategic direction and key initiatives. Project leaders are invited to submit their proposals through open, rigorous, and selective procedures to receive government support.
• Is overseen by the General Secretariat for Investment on behalf of the Prime Minister and implemented by the French Agency for Ecological Transition (ADEME), the French National Research Agency (ANR), Bpifrance, and the Banque des Territoires.

Visit france2030.gouv.fr to learn more.

 

Media Contact
Milorad Doljanin – Ecology Media
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