This study presents a comprehensive exergy and sustainability assessment of sugar beet production in two major agricultural regions of Iran; Cherdavel (Ilam province) and Islamabad (Kermanshah province) using the Cumulative Exergy Consumption (CExC) approach. The specific exergy of sugar beet was estimated from its chemical composition as 4.1497 MJ/kg, closely corresponding to the reference value of approximately 4.15 MJ/kg reported in the literature. The total CExC was calculated as 134,398 MJ/ha for Cherdavel and 153,248 MJ/ha for Islamabad, with manure (59.5% for Cherdavel, 62.6% for Islamabad), electricity (13.6% for Cherdavel, 9.0% for Islamabad), and human labor (11.9% for Cherdavel, 14.7% for Islamabad) identified as the dominant contributors. Cumulative CO₂ emissions were 4,379 kg/ha for Cherdavel and 4,345 kg/ha for Islamabad, with electricity (44.9–34.3%), diesel fuel (16.6–15.2%), and manure (15.8–19.1%) as the primary sources, followed closely by nitrogen fertilizer (14.4–20.1%). The Cumulative Degree of Perfection (CDP) was 1.729 for Cherdavel and 1.300 for Islamabad, indicating that both systems produce more exergy than they consume (CDP > 1). The Renewability Indicator (RI) was 0.578 for Cherdavel and 0.769 for Islamabad, confirming that both systems are partially renewable (0 < RI < 1). The product-exergy-to-CExC balance corresponded to a 72.9% surplus in Cherdavel and a 30.0% surplus in Islamabad, indicating more favorable resource performance in Cherdavel under the adopted CExC system boundary. The findings highlight that manure management, electricity sourcing, and irrigation efficiency are the most critical factors influencing the sustainability of sugar beet production in the study regions. Recommendations include optimizing manure application rates, transitioning to renewable electricity sources, improving irrigation systems, and implementing precision fertilization strategies to enhance exergy efficiency and reduce environmental impacts.
