Techno-economic and environmental indicators in greenhouse dryers: toward standardized metrics and carbon accounting

Abstract

Greenhouse dryers are increasingly recognized as low-carbon post-harvest technologies that combine solar energy utilization with controlled microclimates to enhance agricultural resilience. This systematic literature review explores techno-economic and environmental indicators in greenhouse dryer, with an emphasis on indicator standardization, carbon accounting, system configuration, and product quality. The review applied structured searches across multiple scientific databases and applied inclusion criteria focusing on studies reporting energy, exergy, cost, and environmental metrics. Quality appraisal drew on ISO standards for life cycle assessment and established methodological checklists. Findings reveal substantial heterogeneity in indicator definitions and functional units, with Specific Moisture Extraction Rate, thermal and exergy efficiencies, and economic measures such as payback period frequently reported yet inconsistently applied. Carbon accounting practices are largely confined to operational emissions, with embodied impacts and end-of-life scenarios rarely assessed, limiting the accuracy of sustainability claims. Comparative analysis shows that passive systems provide low-cost options with modest efficiencies, active systems achieve higher throughput at increased operational risk, and hybrid systems with thermal energy storage consistently deliver superior techno-economic outcomes. Importantly, product quality, encompassing color, nutrient retention, and sensory attributes, directly influences market competitiveness, enabling premium pricing and reducing losses. This study highlights the need for harmonized indicator frameworks, comprehensive carbon accounting, and integrative models that connect performance, cost, emissions, and quality. By advancing such approaches, greenhouse dryers can be more effectively scaled to support sustainable agriculture, reduce post-harvest losses, and contribute to climate mitigation.