Comparative LCA model on renewable power solutions for off-grid radio base stations

Abstract: Globally, there are approximately 900 000 telecommunication radio base station sites (RBS-sites)located in areas without access to the electrical grid. Traditionally, these sites are powered by dieselgenerators, consuming large amounts of fossil diesel fuel. Diesel combustion is connected both toenvironmental impacts and high economical expenses for the mobile operators. As the mobilenetwork expansion is increasingly located in off-grid areas of developing countries, the search forrenewable power alternatives has been intensified. This Master thesis presents results from a life cycle assessment (LCA) of photovoltaic and windturbine hybrid power configurations for off-grid RBS-sites. The LCA covers environmental impactsfrom all life cycle activities of the hybrid system: from raw material extraction, manufacturing, andtransportation, to on-site usage, and disposal. To enable assessment of variable hybrid configurations, four scalable sub-models were constructed:one diesel sub-model including the generator and yearly diesel consumption, one back-up batterysub-model, one PV module sub-model and one wind turbine sub-model. Included in the sub-modelswere required site equipment; e.g. foundations for generators, PV modules and battery banks, powerconverters, fuel tanks and possible housings. The number of generators, liters of fuel consumed peryear, number of battery cells, square meters of PV module and number of wind turbines were set asvariables. Hereby RBS-sites with different capacities and availability of renewable source could bemodeled. A hybrid configuration including 21 square meters photovoltaic modules, one wind turbine, a storageof 36 (12 V) batteries and one generator back-up consuming 1500 liters of diesel fuel per year wasevaluated. The hybrid site represents between 11 and 16 percent of the different environmentalimpact potentials, global warming potential specifically representing 13 percent, caused by acorresponding traditional diesel site consuming 20000 liters of fuel per year. The most importantparameters influencing the environmental performance of the renewable hybrid site following thediesel fuel production and combustion are the production energy mix and energy intensive processesincluding the up-stream silicon and lead processing. The thesis confirmed great environmental benefits of using wind and solar power at RBS-sites. Theadditional gain of applying wind power when feasible to decrease the PV module area or batterycapacity required was also demonstrated. The great importance of manufacturing location andelectricity mix should encourage Ericsson to map supplier manufacturing locations, searchingpossibilities to decrease the environmental impacts from the manufacturing phase of the differentsub-systems.