Reducing emissions using renewable sources for electricity generation in Stewart Island

The electricity is generated in a traditional way extensively using diesel in off-grid areas. However, it increases the consumption of fossil fuels and carbon emissions and therefore it is essential to find alternative solutions to help reaching sustainability goals. The case study is Stewart Island, where the electricity is provided by a distribution network powered by up to five diesel generators at a central diesel power station. Local residents believe that reducing the consumption of diesel and having a renewable source of electricity generation are two of the island’s highest priorities. HOMER PRO software is used to compare current diesel generators system with a hybrid system merging a tidal energy source (predictable) with wind (unpredictable) and diesel (back-up), through a microgrid. Using two wind and four tidal turbines, plus one diesel generator for back-up, produces the highest renewable fraction (61.1%) and reduces the fuel consumption and green gases emissions (GHGs) 199,176 l and 534,061 kg/yr, respectively, in comparison with using diesel station. Its levelized cost at 21 c/kWh is also more cost-effective rather than 23 c/kWh in the present scenario.