Jimmy and Calogena reach a new milestone in the development of reactors for heat production
Supported by the French State as part of the France 2030 programme, the French startups Jimmy and Calogena are reaching a new milestone in the development of their reactors dedicated to heat production. Both companies have announced significant fundraising rounds to prepare for the industrial phase and their first projects in France and Europe.
At the Nuclear Energy Summit in Paris on 10 March, a series of announcements were made in support of small nuclear reactors. The President of the European Commission, Ursula von der Leyen, presented a €200 million guarantee fund to attract financing. Emmanuel Macron called for “mobilising Important Projects of Common European Interest to finance nuclear, and in particular SMRs.” In this context, the French State took action by confirming its support for the two French startups Jimmy and Calogena under the “innovative nuclear reactors” call for projects of France 2030. The two project developers are the first to enter phase 2 of this programme. Building on this announcement, the two startups, which are targeting the heat market, announced that they had raised €100 million and €80 million respectively, partly financed by public funds.
Calogena: direct air capture in sight
A subsidiary of Groupe Gorgé, Calogena carried out a capital increase totalling nearly €100 million, including €48 million provided through the France 2030 programme. “These very significant amounts give us visibility for more than two years. By 2028, we will have completed the detailed design of our reactor, submitted our application for a construction licence for our first-of-a-kind unit, and secured our first commercial successes in France and Europe,” said Julien Dereux, Chief Executive Officer of the company, in a statement.
Selected under phase 1 of the “innovative small nuclear reactors” call for projects with €5.2 million in subsidies, the CAL30 reactor (30 MWth) aims to address the district heating market. Derived from pool-type reactor designs, the concept allows operation at low pressure (6 bar) and low temperature (100°C). “The very limited number of auxiliary systems makes the concept inherently simpler and safer than all conventional reactors,” Calogena states, noting that it submitted a third application for an opinion to the ASNR on safety options in January 2026. In France, a demonstrator at the CEA site in Cadarache is being considered and studied, although no final agreement has yet been signed.
At the same time, Calogena is already preparing for international deployment, particularly in Finland. The company has positioned itself to participate in siting studies for its reactor to supply district heating networks in Kuopio and in the capital, Helsinki. In this context, the CAL30 reactor is currently under pre-licensing review by STUK, the local nuclear regulator. Overall, Calogena has launched “five projects in France and Finland, totalling 20 reactors.”
Jimmy: preparing for industrialisation
The other company selected for phase 2 of the call for projects, Jimmy, has obtained additional funding of €80 million, half of which comes from public funds. This funding follows an initial €32 million support received through France 2030 in 2023 and “brings the total private funding raised since the company’s creation in 2020 to more than €60 million.” “These resources will make it possible to finalise the detailed design of the generator and to prepare the industrial conditions for its deployment, notably through the industrial base established in Le Creusot and the structuring projects carried out with its suppliers,” Jimmy stated in a press release.
In parallel with this capital increase, Jimmy has also signed a contract with Onet Technologies for the manufacturing of its reactor vessel. “Securing this partnership marks a new decisive step in the industrial realisation of Jimmy’s project, mobilising leading French expertise for this critical component,” the company commented.
Jimmy is one of two companies, alongside Stellaria, to have reached the stage of review of the application for a construction licence for a unit to be located at the Cristanol industrial site in Bazancourt. Submitted in February 2025, the application must be completed by March 2026. This project illustrates the market Jimmy aims to enter: industrial heat production. Its high-temperature reactor (HTR) technology enables thermal output of 20 to 60 MWth and temperatures of up to 470°C. A potential market of 700 thermal generators in France and Europe has been identified by Jimmy, as explained by Antoine Guyot and Mathilde Grivet, respectively CEO and Managing Director of the company, during a Sfen webinar.
Nuclear heat: a promising market
The announcements by the two French startups illustrate the opportunities represented by heat production for new nuclear. “Technically addressable decarbonised heat demand in France by SMRs/AMRs is currently estimated at more than 80 TWh per year and could exceed 100 TWh by 2050,” notes a study by E-Cube, commissioned by Sfen and published in April 2025. Assessing market prospects for this sector, complementary to large-scale reactors, the analysis highlights the main areas of demand by 2050: industrial heat (70 TWhth), district heating (30 TWhth), and potentially carbon capture (10 to 15 TWhth) and high-temperature electrolysis (0.5 to 3 TWhth). ■