Techno-economic Analysis of Options to Achieve 100% Renewable Electricity for Samoa

Abstract

To reduce greenhouse gas emissions and reliance of fossil fuels Samoa has developed a target of achieving 100% renewable electricity by 2025. Currently 60% of Samoa’s electricity comes from diesel generators and the details of how this target will be achieved are not clear. The research in this thesis aims to provide a better understanding of how to achieve this target by analysing possible future renewable electricity supply scenarios. This analysis is based on simulating detailed demand and renewable supply time series based on modifying historical data to: (i) develop approaches to deal with variability in electricity supply from renewable resources and to study the trade-offs (i.a) between renewability and efficient use of resources, and (i.b) between renewability and economics viability.

Due to excellent solar resources, our results show that it is technically feasible to achieve close to 100% renewable electricity supply in Samoa with a combination of solar photovoltaics, hydro and electricity storage. The most promising scenarios to achieve this have shares of solar, hydro and stored solar electricity supply in the range of 28 - 37%, 25 - 40%, and 17 - 30%, respectively. Storage size range of 110MWh to 180MWh was found to be critical to achieving these results.

Exploration of a range of scenarios showed a trade-off between very high penetrations of solar and efficient use of resources, i.e. a significant proportion of electricity produced would need to be “spilt” as generation significantly exceeds demand much of the time due to the temporal mismatch between supply and demand.

The results also showed that very high percentages of renewables (> 90%) would result in prohibitively high costs. However, by optimizing storage size it was possible to find scenarios that achieve ∼90% renewable supply and, based on an indicative analysis, also appear economically viable with an NPV>0 and an LCOE that is below the current costs to produce electricity from diesel in Samoa.

These results show that achieving close to 100% renewable electricity in Samoa is possible and may even be cost effective. They also provide a picture of what this future electricity system might look like. Future work should focus on exploring cost effective storage options, detailed economic analysis of actually implementing such a scenario, and approaches to low-carbon transport.