About This Project

This project explores the use of lichen to transform existing concrete structures into passive greenhouse gas sinks. By identifying high-performing lichen strains, assessing their impact on concrete, and developing scalable application methods, we aim to integrate lichen into urban infrastructure with minimal disruption. This nature-based approach offers a low-cost, sustainable solution for long-term CO₂ and methane removal, enhancing air quality while leveraging existing cityscapes.

Ask the Scientists

Motivating Factor

Cement is a vital part of global infrastructure, with more than 4 billion tons produced annually, accounting for around 8% of global carbon dioxide (CO₂) emissions[1]. While efforts to reduce emissions during manufacturing are important, cement production will always generate CO₂ as a fundamental byproduct of its chemical processes.

Developing an alternative strategy that leverages natural symbiosis to enable cement to achieve net-zero CO₂ emissions over its lifetime would significantly reduce the carbon footprint of urban developments and enhance air quality in urban areas. By fostering lichen growth on concrete surfaces, we not only enhance CO₂ uptake but also introduce a potential methane removal pathway, as certain lichen-associated microbes have been shown to consume CO₂ and methane[2][3]. This dual-benefit system could help mitigate two potent GHG simultaneously, transforming cement from a carbon emitter into a functional carbon sink on existing concrete structures.

Specific Bottleneck

While lichen has demonstrated the ability to absorb CO₂ and potentially capture methane, its application to concrete surfaces—particularly existing buildings—poses challenges. The suitability of various lichen species for colonizing concrete must first be established, as while capable of inhabiting extreme environments, their ability to thrive in harsh urban conditions while maximizing GHG uptake remains unexplored. Some methods for new construction foster plant growth, but they can be costly and don’t address the millions of currently standing buildings[4]. A method for integrating lichen onto existing structures while preserving both building integrity and lichen health is crucial to maximize this technology’s potential for GHG removal in urban environments. Lichen hold significant potential for providing measurable, long-term GHG removal in urban areas, they just haven’t been studied in this way before.

Actionable Goals

Lichen strains suitable for optimal GHG uptake need to be identified. This will involve conducting studies to quantify the CO₂ and methane uptake of different lichen species.

Along with testing suitable lichen strains, investigation of lichen-enriched concrete substrates to characterize the CO₂ uptake of lichen-concrete structures and understand where carbon storage occurs within the concrete matrix are needed. These studies will generate insights into scalability, growth optimization, and maintaining the structural integrity of lichen-enriched concrete, all while maximizing GHG sequestration.

Finally, a method for applying lichen to existing concrete structures is crucial and currently unexplored. This will involve creating a low-cost, scalable approach for applying lichen to structures such as parking garages, office buildings, and industrial facilities to maximize potential for future application.