ENERGY-CROPS-BASED BIOGAS PLANTS IN GREECE: ECONOMICAL COMPARISON OF MAIZE AND SWEET SORGHUM SILAGES USED AS FEEDSTOCK

摘要

Comparing storability and the energy yieldof biogas production from individual feedstock, energy cropsrnperform better than most organic wastes such as manure and food waste and therefore in several European countriesrnbiogas is produced using energy crops. The most frequently used energy crop is maize silage. However, althoughrnmaize has a high biomass yield, it requires high amounts of irrigation water, rendering it a very costly energy crop inrnthe case of Southern European countries, such as Greece. Therefore an alternative energy crop in replacement tornmaize should be evaluated. A promising energy crop for Greece is sweet sorghum, which exceeds the biomass yieldrnand requires less water and agrochemicals in comparison to maize. Thus, the aim of this study is to evaluate and torncompare from an economic point of view these two potential energy crops as feedstock for biogas production. Tornservice this aim, techno-economical assessments of detailed cultivation techniques and energy crop cost productionrnwere performed, and the overall investment and operational costs of biogas plants with various sizes were estimated.rnThe results indicate that sorghum-based biogas plants would theoretically be economically feasible in Greece at750rnkWel and higher electrical output, while maize-based biogas plants are feasible at sizes higherthan 1MWel(for arnpayback period of less than 10 years).