2025 Teens Dream - GreenShield: Preserving Food, Protecting the Planet, Empowering Communities

Every year, approximately 1.3 billion tons of food ends up wasted. In the United States alone, nearly 40% of the food supply is wasted. Fruits and vegetables are some of the most frequently discarded items, with 45% lost somewhere between farm and fork. When this produce decomposes in landfills, it produces methane, a potent greenhouse gas. In fact, about 6%-8% of all human-caused GHG emissions could be reduced if we stop wasting food. Ethically, food waste is troubling given that more than 50 million people in the US turned to food assistance. Even for those who can afford it, such constant spending creates a burden. In the US, those in the lowest income quintile spent  32.6% of their after-tax income on food. Produce waste must be mitigated, both for the pocket and the planet, and natural processes play a significant role in this solution. Fruits and vegetables emit ethylene gas, a plant hormone accelerates spoilage. Additionally, bacteria and mold spores  begin to decompose produce from the moment it is harvested, further contributing to its deterioration. 

What is Greenshield? 

GreenShield is an eco-friendly, hexagonal device engineered to extend produce freshness by managing ethylene and CO2 levels in food storage. Constructed from biodegradable PLA and powered by Basolite C300 (an efficient ethylene adsorbent), GreenShield extends freshness 16%+ longer than existing products by combining ethylene capture, CO2 release, and antimicrobial oil cartridges. For households, this means potential annual savings of $300–$500. Grocery stores, restaurants, and food suppliers can also expect to reduce spoilage, especially while transporting food from the source to the market. Uniquely, using an internal DS18B20 sensor, GreenShield dynamically adjusts storage conditions such as temperature and offers users app notifications about food quality in real time. This app integration also teaches users more about food preservation, tapping into a global market eager to embrace sustainable innovation.

The Science and Engineering Behind GreenShield

Constructed from PLA (polylactic acid), a biodegradable material derived from renewable resources, GreenShield’s hexagonal prism structure features porous walls that allow ethylene molecules (approximately 4.18 Å in size) to diffuse through, enabling dynamic control of ethylene concentration within the container. Hexagonal designs provide a high ratio of surface area to volume,  maximizing exposure to ethylene molecules, and previous studies have demonstrated that porous structures with optimal geometric configurations improve molecular diffusion and adsorption kinetics. The study “Comparative study of hexagon & square windcatchers using CFD simulations” found that the air change rate is better in the hexagon shape, making it an ideal choice for GreenShield.

Central to GreenShield’s design is Basolite C300, a copper-based metal-organic framework (MOF) optimized for ethylene adsorption. A Eureka text in our research was the Michigan State University study titled “Metal-organic frameworks have utility in adsorption and release of ethylene and 1-methylcyclopropene in fresh produce packaging” which compared Basolite C300,  Basolite A520 and Zeolite Z13X to identify the superior performance in binding to ethylene. Basolite C300 far surpassed Zeolite Z13X, the more commonly used absorbent in products similar to GreenShield. A continued literature review into the characteristics of Basolite C300  supported the study.  This enhanced ethylene capture capacity slows the ripening of produce, enabling GreenShield to outperform other solutions on the market. Furthermore, GreenShield incorporates CO₂ desorption technology, using Peltier modules (TEC1-12706) to heat the Basolite crystals and release CO₂, which contributes to prolonged produce freshness. Temperature is managed through a DS18B20 sensor and an ESP32 microcontroller, which monitors and adjusts the system in real-time for optimal preservation. GreenShield also addresses common spoilage challenges through an antimicrobial essential oil cartridge that releases thymol compounds to reduce bacteria and mold, particularly for leafy greens, which spoil from bacterial growth. 

The GreenShield app enables users to remotely monitor ethylene and CO₂ levels through MiCS-5524 sensors, sending mobile alerts when ethylene rises to a threshold that indicates ripening. Unique features like recipe suggestions for soon-to-expire produce encourage timely consumption, supporting waste reduction. Specifically, we will have an ethylene sensor connected to pin A0, and a temperature sensor on pin A1. In the loop, the code continuously reads data from the sensors, converts it to meaningful values (e.g., ethylene concentration in ppm and temperature in Celsius), and classifies the levels into “low,” “medium,” or “high” with corresponding color codes. Premium GreenShields will be equipped with a mini-camera which will send images to our back-end, which will then be analyzed by the Spoonacular API to generate recipe ideas for users.

SDGs Connection

SDG 12 of the United Nations’ 2030 Agenda focuses on ensuring sustainable consumption and production patterns. GreenShield directly contributes to this goal by tackling food consumption at various points in the supply chain, including households, grocery stores, restaurants, and food suppliers. Specifically,  GreenShield significantly extends the shelf life of produce by over 16% using advanced ethylene adsorption and carbon dioxide management. This innovation addresses food spoilage throughout the supply chain, from farm to table. By reducing food waste, GreenShield helps mitigate the environmental impact of decomposing organic matter, which contributes between 6% and 8% of global human-caused greenhouse gas emissions. The GreenShield app also empowers consumers to make more sustainable choices by providing real-time data on produce freshness and offering recipe suggestions for items nearing expiration. This functionality fosters mindful consumption and reduces unnecessary waste. Additionally, the app includes educational resources on food preservation techniques, promoting long-term behavioral shifts toward sustainability. GreenShield also supports sustainable production practices by minimizing food losses during transport and storage, ensureing more efficient production and delivery processes for food suppliers and distributors. The device itself is constructed from biodegradable PLA and renewable materials, further emphasizing GreenShield’s commitment to SDG 12. Additionally, the Zero Hunger Challenge (SDG 2) envisions a world where food systems are sustainable and no food is lost or wasted, and GreenShield will bring this to life.  GreenShield will combat spoilage, a common source of waste, by addressing primary causes of produce deterioration, including ethylene accumulation, bacterial growth, and mold development. Its dual action of ethylene adsorption and antimicrobial protection is particularly effective for preserving highly perishable items like leafy greens.