The integration of pelletized agricultural residues into electricity grid: Perspectives from the human, environmental and economic aspects

Abstract

Agricultural residues are generated during the growing and harvesting of crops; consequently, its availability is linked with the local demand, socioeconomic status, climatic conditions as well as national policies. Only a fraction of these residues has a specific use, mainly in poultry and livestock breeding; however, there is potential to use them as bio-energy feedstock. A strong dependence on oil, as a primary energy source, has resulted in huge environmental problems, particularly climate change. Hence, the use of agricultural residues, particularly those that seem not to have any environmental or economic value; as a feedstock for electricity production, could be an attractive alternative in terms of economic, environmental and social benefits.Therefore, this paper is focused on evaluating these potential benefits from the production of fuel pellets using agricultural residues available from different crops; and their use as a renewable feedstock for electricity production in existing power plants. Life cycle assessment is included in the analysis to get the optimal integration between conventional and non-conventional feedstocks for generating electricity. In addition, the economic aspect was calculated taking under consideration all the activities included in the supply chain for the production of fuel pellets. Also, Human Development Index approach was considered for evaluating the social benefits achieved by the use of renewable fuel pellets. The proposed mathematical model includes all the material balances involved in the supply chain for the production of fuel pellets; also, binary variables were used as decision variables to evaluate the plant installation, giving a mixed integer linear mathematical model optimization. For this case study, parameters of the Mexican electric power grid were used; however, the model can be applied to any other case. The results show that it is possible to provide 200,899 GWh per year of the electricity to cover the demand in Mexico through pellets combustion obtained from agricultural residues. In addition, a carbon dioxide reduction of 20% and 11% increase in social benefit were achieved. Then, the agricultural residues revalorization as solid bio-fuel alternative for the electric power grid has positive economic, social and environmental impacts.