Selling Green with Trust: Architecting a blockchain-based GreenTech Registry Platform for Climate Actions in Transportation (CAT)

Green technology (GreenTech) represents the innovation frontier for sustainability that mitigates environmental impacts and climate change. However, existing GreenTech registry platforms are hampered by centralized architecture, opaque verification, and limited traceability. To overcome these challenges, this study proposes a blockchain-based GreenTech registry platform designed to enhance trust, verifiability, and transparency for transportation-related climate actions. First, built on the Ethereum public blockchain, the platform employs a dual architecture that combines on-chain immutability for ownership records, verification outcomes, and procurement contracts with off-chain PostgreSQL storage for high-frequency operational queries. Second, we define a suite of smart contracts for digitalizing GreenTech as immutable digital assets and quantifying GreenTech provider trustworthiness through a standardized credibility score. Finally, an illustrative application based on the U.S. Congestion Mitigation and Air Quality (CMAQ) program demonstrates how the blockchain-based GreenTech registry would disseminate verifiable technology metadata, provide transparent verification trails, and facilitate GreenTech portfolio selection to decarbonize transportation. The experimental stress tests show that reliable blockchain performances need to modularize the transactions and configure the optimized text and image sizes (text ≤ 5 KB and images ≤ 100 KB), which can provide implementable guidance for industrial deployment and policy integration of credible GreenTech in the transportation sector. The results indicate that the dual architecture combining on-chain accountability with off-chain efficiency can strengthen trust, reduce verification delays, and provide actionable evidence for CMAQ-like programs and other public procurement settings.