Athula D. Rajapakse received the B.Sc. (Eng.) degree in electrical engineering from the University of Moratuwa, Moratuwa, Sri Lanka, in 1990, and the M.Eng. degree in energy (energy technology) from the Asian Institute of Technology, Bangkok, Thailand, in 1993, and the Ph.D. degree in quantum engineering and systems science from the University of Tokyo, Tokyo, Japan, in 1998. Currently, he is a Professor at the University of Manitoba, Winnipeg, Manitoba, Canada. He is a Registered Professional Engineer in the Province of Manitoba, Canada. His reserach interests include power system protection and grid integration of distributed and renewable energy systems.


The Northern off-grid power systems in Canada mostly rely on diesel as their primary energy resource. Many of these communities do not have overland roads and therefore rely on winter roads for transportation of diesel. Transportation of diesel over winter roads is costly and hazardous to both people and environment. On the other hand, growing fuel prices and the adverse effects of increased carbon footprint have shifted the energy policies to favor more environmentally healthy approaches. In this context, Hybrid Renewable Energy Systems (HRES) deploying locally available renewable energy sources and energy storage methods have emerged as perfect candidates to compete with the existing diesel-based facilities. High penetration of renewable sources is expected to reduce, optimize or replace diesel-based energy production while increasing the carbon-free generation capacity. To maximize the envisioned benefits, technology selection, optimum sizing and performance evaluation have become decisive steps in the designing process of HRES. This study aims to find the optimum HRES retrofit  for an exiting diesel-based off-grid power system. The desicion variables employed in the optimization process ensure the technical feasibility and economic viability of the selected configurations while indirectly addressing their envionmental friendliness. Four HRES configurations with increasing renewable penetration were optmized using NREL’s HOMER software platform. The performance of each optimized system was assessed in terms of economical, technological and environmental criteria. Results reveal the competence of HRES in delivering high envionmental performance, energy security and enhanced reliability while achieveing fuel savings up to 20-23%.