Cradle-to-grave life cycle assessment of a PV-diesel hybrid system : the case of a Lebanese industrial facility

Abstract

Many countries in the world today are striving to achieve a more sustainable power system through an increasing reliance on renewable energy sources. While Lebanons commitment to the path of sustainable energy production through renewable sources has been initiated by the governments pledge in Copenhagen in 2009, the country still lacks effective implementation of this commitment. The advantages of photovoltaic (PV) energy generation include the reduction of carbon dioxide (CO2) emissions as well as fuel costs. A hybrid energy system is an electrification system that provides energy using a combination of both renewable and conventional energy sources with the optional incorporation of a battery. Such a system is more realistic then photovoltaic systems for facilities having a larger energy demand. Although a photovoltaic system reduces the emissions of CO2, it is still necessary to ensure whether a hybrid system can lower the harmful environmental impacts over its entire life cycle including its assembly, use phase, and end of life. Life Cycle Assessment (LCA) is a tool to evaluate the environmental impacts of any product, process, or service, from the extraction of raw materials to the disposal or end-of-life. The objective of this report is to evaluate the environmental impacts of a PV/Diesel hybrid system and compare these impacts to the impacts of a conventional diesel generators system. The case study is the "LibanJus" juice products factory located in the city of Hadath in Mount Lebanon. Its energy demand is 6000 MWh/year. The components of the LibanJus hybrid energy system are a 420 modules PV generator, 7 three-phase grid dependent inverters, three 1000 KW Caterpillar generators and a 500KW Cummins generator. Simapro 8.0is the software used to conduct the LCA study. The ecoinvent database is used to model the Life Cycle Inventory and the IMPACT 2002+ methodology is used for the Life Cycle Impact Assessment. The cradle-to-grave life cycle assessment of this PV-diesel hybrid system showed that the manufacturing of the photovoltaic modules and the additional system components contribute greatly to the environmental impacts. However, this contribution is later reduced by the use of the PV system alongside the genset. Indeed, the use phase results show that the incorporation of the photovoltaic system reduces the potential impacts of the entire system during its life cycle. Two end-of life scenarios are also taken into consideration: a landfill/incineration scenario as well as a recycling scenario. The results show that a recycling scenario contributes to lowering the overall environmental impacts of the PV-diesel hybrid system.