Carbon13 is launching its tenth SEIS fund, Carbon13 SEIS Fund X, with exclusive rights to invest in startups built through its venture builder in Cambridge.
Carbon13 is a climate tech venture builder based in Cambridge and Berlin, and has invested in 107 startups since 2021 across the UK and EU.
The new fund will invest in startups operating within the climate horizontal covering energy, AI, materials, food security, supply chain resilience and more to back the next generation of climate tech innovators.
The firm’s venture builder programme brings an ecosystem of hundreds of domain experts, investor partners, scientific advisors and industry partners. Because of this, Carbon13 SEIS Fund X achieves the diversification of a sector-agnostic fund with the deep specialist knowledge of a vertical-focused fund.
Carbon13 says this means the fund can pick startups it knows can perform in the industries of 2026 who are looking for deployability, application of AI, scalability of energy and energy efficiency, supply chain resilience, value capture and more.
Notable portfolio alumni include Cocoon Carbon, which raised a $15m (£11.2m) Series A in March to decarbonise steel and cement, and MatNex, an AI materials discovery platform.
“In 2026, the bar is raised for pre-seed investors. The mix of opportunity and uncertainty means that it’s more important than ever that founders are getting their go-to-market strategies right first time – it’s not just about who has capital to deploy, but how they can support the founders post investment,” says Michael Langguth, co-founder and chief strategy officer at Carbon13.
“Top founders are looking for investors who are industry connectors for pilots and investment, referrers for key first hires, conduits for innovation, participants in follow-on rounds, [and] true partners for success – all things Carbon13 was built to do. The Carbon13 SEIS Fund X has exclusive access to all that value.”
