Designing synergies between hybrid renewable energy systems and ecosystems developed by different afforestation approaches

Abstract

In this study, we explore the possibility of techno-ecological synergy (TES) based sustainable design of hybrid renewable energy systems (HRES) and their surrounding ecosystems to mitigate emissions. We consider an HRES system with a photovoltaic cell, wind turbine, fuel cell, electrolyzer, and diesel generator. The NO2 and CO2 emissions from HRES have been conventionally treated using a selective catalytic reactor and monoethanolamine (MEA), respectively. However, a forest ecosystem can naturally uptake NO2 and CO2. Therefore, we have considered the forest ecosystem as an additional unit operation in this study and its growth dynamics have been incorporated in the system design. Thus, we analyze two approaches to remediate emissions from the HRES: (1) technological approach — SCR and MEA, (2) TES approach — forest ecosystem in tandem with technology. Unlike previous TES design studies, we focus on cities in India and compare a traditional method for forest restoration and a faster Miyawaki method considering their growth dynamics. Furthermore, we consider the case of social forestry, which is relevant in developing countries. Here, the trees are pruned, which increases the pollution uptake rate. We find that the emission abatement technology cannot be removed from the system as it is needed for seasons wherein trees shed their leaves; therefore a periodic profile of technology utilization for emissions abatement is observed. We find the TES approach to be more economically feasible for pollution uptake than a purely technology based approach for the sustainable operation of HRES at Delhi and Chennai in India, respectively. Based on this, the annualized cost of electricity generation is found to be 15% less than the base case. Moreover, the study reveals that annualized cost of electricity generation associated with the Miyawaki method is 13% less than the traditional reforestation method for attaining TES designs.