Request for Applications

Greentown Labs requests applications from innovative startups with advanced CO₂ mineralization and carbonation technologies for materials, including concrete aggregates. Greentown Go Build 2026 with Amazon and the Global CO₂ Initiative at the University of Michigan aims to accelerate the development and implementation of sustainable materials to decarbonize building practices for Amazon’s operations and the broader construction industry.

Program benefits for startups

• A structured accelerator platform for testing and collaboration with Amazon to explore potential future opportunities. This program focuses on performance data collection, economic analysis, implementation strategy development, and more. 
• A needs-based stipend for each selected startup to support their participation in the accelerator
• Mentorship, networking opportunities, and partnership-focused programming from the Greentown Labs community of climatetech startup experts
• Exclusive access to the Greentown Labs and Amazon networks 
• Desk space within Greentown Labs and access to community programming and events for the duration of the program

What we’re looking for

Concrete production accounts for approximately 8% of global CO₂ emissions, with cement manufacturing responsible for roughly 80% of concrete’s carbon footprint despite comprising only 17% by weight. While significant decarbonization efforts target cement through supplementary cementitious materials (SCMs), alternative clinker chemistries, and carbon capture technologies, aggregates represent an underexplored opportunity for carbon reduction. These aggregates present a substantial opportunity for CO₂ mineralization and permanent sequestration. 

CO₂ mineralization in aggregates typically occurs through the carbonation of calcium and magnesium oxides and silicates, forming stable carbonate compounds. This chemical process not only sequesters CO₂ but can also enhance material properties. Furthermore, CO₂ mineralization in aggregates presents unique synergies with existing concrete decarbonization strategies. 

Go Build 2026 brings together startups with Amazon for joint structured assessment, testing, and validation to advance CO₂ mineralization technologies and commercial readiness, enabling implementation across Amazon’s construction portfolio while advancing sustainable building practices for the broader construction industry. 

We’re looking for startups at TRL 4 and above that demonstrate economic viability, with clear pathways to cost-competitive production. 

Technology Scope Areas

Aggregates utilizing waste CO₂ are the primary focus of the program, although other materials that could arrive at the jobsite in concrete with CO₂ as an added ingredient are also eligible. 

Examples of specific technologies of interest include:

Emerging Technologies in CO₂ Mineralization for Aggregate Production, such as:

• Accelerated mineralization processes
• Processes that directly use flue gas CO₂ without further separation 
• Advanced particle processing technologies

Products incorporating anthropogenic CO₂ as feedstock, additive, or curing input, yielding durable construction products that approach or exceed carbon neutral lifecycle GHG emissions relative to conventional baselines. Categories include:

• Aggregates
• Precast concretes
• Concrete fillers
• Supplementary cementitious materials (SCM’s)
• Fiber cement board and drywall
• Insulation

The following solutions are not in scope for this program:

• Products lacking safe, stable performance for >100 years of service life
• Circular carbon products without durable incorporation of CO₂ (e.g., fuels)
• Avoided emissions products without embodied carbon

Collaboration with Amazon

Through structured assessment, testing, and validation, Go Build 2026 aims to develop practical implementation pathways for sustainable building materials production.

Amazon is open to the following types of collaborations with startups selected for this program:

• Validated technical pathways for CO₂ mineralization in concrete aggregates
• Performance data under real-world construction conditions
• Economic models for commercial-scale implementation
• Integration protocols for existing concrete production facilities
• Quality control and testing methodologies
• Supply chain optimization strategies

Eligibility

• Submit your completed application through the online portal by Friday, January 9, 2026
• Be available for virtual and/or in-person interviews after the application deadline, if selected for further rounds 
• Disclose the status of any intellectual property (IP) relevant to your submission. Do not submit confidential information in the application process. Awardees will enter into non-disclosure agreements in order to protect their intellectual property throughout Go Build 2026.
• Applicants may apply from anywhere in the world, however executive or founder-level attendance at five events (one virtual and four in person at Greentown Labs Somerville and/or Greentown Labs Houston) is mandatory for participation in this program.
• A tentative program timeline is as follows:
  • Kickoff Event: April 1, 2026 
  • Workshop 1: May 20-21, 2026
  • Workshop 2: June 24-25, 2026 (Virtual)
  • Workshop 3: August 12-13, 2026
  • Final Showcase: October 1, 2026 

Greentown is committed to increasing diversity, maintaining an inclusive community culture, and creating a more sustainable planet for all. We welcome applications from founders and teams of all backgrounds, regardless of their ethnicity, race, gender, religious beliefs, sexual orientation, age, marital status, veteran status, or whether or not they have a disability.

• ABOUT GREENTOWN LABS

  Greentown Labs is a 501(c)(3) nonprofit accelerating climatetech innovation and commercialization by empowering entrepreneurs and enabling collaboration. As the largest climatetech and energy startup incubator in the world—with locations in Somerville, Mass. and Houston, Texas—Greentown convenes the climatetech ecosystem to provide entrepreneurs the community, connections, and resources they need to thrive. The incubator offers lab space, shared office space, machine shops, electronics labs, tool shops, software and business resources, and a large network of corporate customers, investors, philanthropists, and more. Greentown is home to more than 200 startups and has supported more than 625 since its founding in 2011; these startups have collectively created more than 16,500 jobs and raised more than $9.6 billion in funding. For more information, visit www.greentownlabs.com or follow Greentown on LinkedIn.

• ABOUT GREENTOWN GO

  Greentown Labs’ Greentown Go programs inject momentum and traction into startup-corporate collaborations to decarbonize the global economy, unlocking the power of climate solutions at scale. These open-innovation programs operate along five tracks, corresponding to the five major greenhouse gas-emitting sectors: Go Build (buildings), Go Energize (energy and electricity), Go Grow (food and agriculture), Go Make (manufacturing), and Go Move (transportation). Each track leverages the same proven Greentown Go framework that has delivered dozens of partnership outcomes to date, including pilots, licensing agreements, investments, joint development agreements, and more.

• About Amazon

  Amazon is guided by four principles: customer obsession rather than competitor focus, passion for invention, commitment to operational excellence, and long-term thinking. Amazon strives to be Earth’s Most Customer-Centric Company, Earth’s Best Employer, and Earth’s Safest Place to Work. Customer reviews, 1-Click shopping, personalized recommendations, Prime, Fulfillment by Amazon, AWS, Kindle Direct Publishing, Kindle, Career Choice, Fire tablets, Fire TV, Amazon Echo, Alexa, Just Walk Out technology, Amazon Studios, and The Climate Pledge are some of the things pioneered by Amazon. For more information, visit amazon.com/about and follow @AmazonNews.

• About the Global CO2 Initiative

  The Global CO₂ Initiative at the University of Michigan recognizes that addressing climate change requires using multiple strategies simultaneously. Nature based solutions like planting trees are a necessary part of the solution, but they are not enough by themselves. By recognizing that excess atmospheric carbon dioxide is a valuable resource for making products, we can drive billions of dollars in economic development, help meet our environmental and climate goals, and ensure reliable supply chains for the future.

Contact

• Marinna Teixeira, Director of Programs, Greentown Go, mteixeira@greentownlabs.com