Using agricultural residues to support sustainable development: A case study of coffee stems gasification to supply energy demands in rural areas of Colombia

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Abstract

The development of sustainable bioenergy plays an active role in the decarbonisation of the energy sector. Unlike other renewables, bioenergy has the potential to expand its applications beyond climate change mitigation by providing complementary environmental and socio-economic benefits that support the Sustainable Development Goals. The deployment of bioenergy could be particularly beneficial in the rural areas of many low and middle-income countries where traditional uses of biomass still prevail. Locally available biomass in rural areas, such as agricultural residues, could be harnessed in more efficient and sustainable manners, and this could be promoted with bioenergy development. The roll-out of these technologies also arises challenges across the environmental, economic and social dimensions, especially for emergent technologies. Tackling these challenges requires a wider understanding of bioenergy technologies™ impacts across these dimensions, and this could be achieved through comprehensive and integrated assessments that investigate these dimensions. This research, therefore, seeks to gain further knowledge to unfold the following questions; how bioenergy technologies using agri-residues could be sustainably and feasibly deployed?, and what are the wider co-benefits, from a sustainable development perspective to rural communities and agro-industries?. This study aimed to evaluate the feasibility of small-scale gasification systems to generate power and heat, using indigenous agricultural residues, to meet the energy demand of rural areas. Considering also that bioenergy is set within local contexts, this research was framed in a case study on the coffee sector in Colombia, using coffee stems as feedstock. The methodology in this research consisted of a combination of multidisciplinary approaches, comprising process modelling for a technical assessment, lifecycle assessment (LCA) and techno-economic analysis. The results of the technical assessment indicate that the gasification of coffee stems could generate a fuel gas suitable for power generation in engines. In addition, the heat recovery and integration to supply the demand for coffee processing could enhance the conversion efficiency of the system. The LCA results show that deploying the coffee stems gasification-CHP system could impact positively on many environmental issues, including climate change, when traditional biomass uses and energy production using fossil fuels are replaced. However, trade-offs should be considered for certain scenarios, such as those replacing grid electricity with high-hydropower generation. The evaluation of the economic feasibility indicates that costs of power generation in the gasification systems could equalise the costs of Diesel-power generation when the system reaches high capacity factors. Matching the grid-electricity tariffs is more difficult to attain even at high capacity factors. The integration of the heat vector in the coffee processing chain contributes to fuel savings and could be translated into a heat credit that reduces the power generation costs. The key findings from this research were integrated under a multidimensional framework that prompted discussions on pivotal drivers, synergies and trade-offs of this bioenergy system. The synergies relate to the importance of balancing the biomass availability and the energy demand in context-specific agricultural sectors. It also emphasises the usefulness of harnessing the biomass conversion by implementing heat recovery pathways in the system, and of maximising the utilisation of the system (increasing the capacity factor) to enhance the systems feasibility. The framework also contributes to understanding how bioenergy from agricultural residues could contribute achieving the Sustainable Development Goals. The multidimensional framework highlights potential co-benefits to rural communities, in relation to improving energy access and health, promoting sustainable agriculture and economic growth, and reducing inequalities in rural areas. In conclusion, this research supports the overarching argument that bioenergy technologies have the potential to deliver energy demands in rural areas while tapping the potential of agricultural residues. Overcoming barriers to these systems deployment is still challenging. Yet, the synergies identified across all the dimensions could help to attain the system™s feasibility and sustainability. Furthermore, wider societal co-benefits to rural communities could also be realised, as suggests the strong correlation between bioenergy and the Sustainable Development Goals.

Keyword(s)

Agricultural residues; Agriculture; Bioenergy; Coffee stems; Gasification; Lifecycle assessment; Process modelling; Sustainable Development Goals; Sustainable development; Techno-economic assessment

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