April Climate & Sustainability Investor Deal Share by 4WARD.earth ⚡♻️ 🌱 💧
10 Climate Startups Worth a Call: April Deal Share is Here
4WARD Editor’s Note
Welcome to this month’s climate deal flow roundup by 4WARD.earth. We’ve identified 10 promising climate and sustainability startups across key sectors that may be actively raising funds or considering a raise in the coming months, which might be worth reaching out to. We’re also continuing our section highlighting recently closed funding rounds worth keeping on your radar :)
🚀 Startups Possibly Looking to Raise
Sector: Energy & Grid Infrastructure ⚡
🇺🇸 Adden Energy (Series A) Founded by Harvard University engineers, Adden Energy develops dynamic-stability solid-state batteries designed to improve safety, charging speed, and energy density for EV and grid applications. The company has commissioned a pilot manufacturing line and is working with early commercial partners as it moves toward scaling production.
🇪🇸 H2SITE (Series A) Bilbao-based H2SITE develops membrane reactor technology that enables on-site hydrogen production and separation, reducing transport costs and enabling decentralized hydrogen deployment. The company is working with industrial partners across Europe and scaling pilot projects.
Sector: Carbon Removal & Climate Infrastructure 🌱
🇬🇧 Mission Zero Technologies (Series A - £21.8M raised to date) London-based Mission Zero develops electrochemical Direct Air Capture systems that remove CO2 at lower energy intensity than conventional heat-heavy approaches. Since its Series A, the company says it has doubled its team and put three DAC systems on the ground, including its first international deployment, giving it strong commercialization signals among European carbon removal startups.
🇧🇷 Mombak (Series A - $30M raised, last announced Apr 2025) São Paulo-based Mombak focuses on large-scale reforestation in the Amazon to generate high-quality carbon removal credits. The company combines land restoration with long-term offtake agreements from global buyers. With growing demand for nature-based carbon solutions and capital deployed at scale, Mombak is likely to require additional funding to expand operations.
Sector: Food Systems & Sustainable Agriculture 🌾
🇫🇮 Solar Foods (Series B ) Helsinki-based Solar Foods produces Solein, a protein made from CO₂, hydrogen, and electricity rather than conventional agriculture. In 2023–24, the company raised additional Series B capital to ramp up Factory 01 near Helsinki and commercialize Solein in food products as the first commercial-scale facility came online.
🇦🇺 SeaStock (Seed / Series A) Australian startup SeaStock develops seaweed-based feed additives that reduce methane emissions from livestock. The company is scaling production and working with agricultural partners to expand commercial adoption.
Sector: Recycle, Circular Economy & Advanced Materials ♻️
🇪🇹 Kubik (Seed) Ethiopia-based Kubik turns hard-to-recycle plastics into low-carbon building materials. The company said its seed funding was being used to increase production in Ethiopia and to support expansion into other African markets, with a subsequent seed extension reported in 2024.
🇳🇱 Circularise (Series A) — The Hague-based digital product passport and mass balance software enabling supply chain traceability for plastics, chemicals, and metals. Working with Neste, Asahi Kasei, and SEKISUI Chemical, positioned for Series B in 2026.
Sector: Water & Climate Adaptation 💧
🇨🇭 Oxyle (Seed — $16M raised Jan 2025) Zurich-based Oxyle develops technology to destroy PFAS in wastewater rather than simply transfer the pollutants elsewhere. The company’s January 2025 seed round was raised to scale deployment of its PFAS-destruction solution for industrial wastewater use cases.
🇮🇳 Aurassure (Pre-Series A) Bhubaneswar-based hyperlocal climate intelligence platform with 2,000+ street-level sensors and AI-physics fusion. Deployed across 200+ Indian and 100+ Brazilian cities; 150% YoY revenue growth.
📣 Recently Closed Funding Rounds
Companies that have just announced closing a raise, worth tracking as they scale and build their teams.
Sector: Distributed Solar & Energy Access 🌞
🇲🇽 Solfium (Series A — $10M closed Apr 2026) Mexico City-based solar platform making distributed solar accessible to Mexican SMEs and corporate value chains. 36,260 panels installed, 25 MW capacity, Series A just closed, positioned for Series B.
Grid Infrastructure & Energy Transition ⚡🔌🏗️
🇨🇭 DePoly (Seed — $23M closed Apr 2025) Zurich-based chemical recycling breaking down unsorted PET plastics to virgin-quality monomers at room temp without fossil fuels. Showcase plant (500 T/year) online summer 2025, targeting full commercial facility 2027.
Sector: Carbon Removal & CDR Infrastructure 🌍
🇮🇹 Tulum Energy (Seed — €22.9M/$27M, Jul 2025) Milan-based methane pyrolysis producing turquoise hydrogen via electric arc plasma reactor (no expensive catalysts, no CO₂). Pilot plant building in Mexico alongside Techint steel ops; commercial viability incoming.
🇨🇭 AIRMO (Seed — €5M, Mar 2026) Swiss GHG monitoring platform using airborne sensors and satellite mission launching 2027. Expanding operations across Europe, the Middle East, and Central Asia.
🗓 Two Upcoming Events Worth Your Time
Two free sessions from the 4WARD network coming up, both relevant if you’re investing or raising in climate and cleantech:
🧾 The Decarbonization Ledger: Unlocking Grants and Proving Financial ROI 📅 April 30 | 5:30pm CEST | Free
How to stack non-dilutive capital alongside equity, model for VC due diligence, and bridge the gap between impact metrics and investor narratives. Built for founders and finance leads actively fundraising. 👉 https://circle.4ward.earth/c/events/the-decarbonization-ledger-unlocking-grants-and-proving-financial-roi
🌍 4WARD Climate Connect: Monthly Global Networking 📅 Monthly | 12pm EST / 6pm CEST | Free
Structured breakout rooms with climate founders, investors, and operators from 100+ countries. No pitching, just real conversations and real follow-ups. 👉 https://circle.4ward.earth/c/events/climateconnect-ef80d5
Both free. Both worth blocking time for.
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Disclaimer: This newsletter is for informational purposes only and does not constitute investment advice. All investment decisions should be made based on independent research and due diligence.