System design issues of high renewable energy system, the case of Eritrea

Abstract

The transition to a low-carbon economy and sustainable development necessitates the widespread adoption of renewable energy resources. This study implemented a novel methodological approach that combines flexibility to evaluate the interaction of various system design parameters and system efficiency through our newly developed system use index. It investigates the interaction among key system parameters, such as storage capacity, hours of storage, penetration, curtailment, wind-solar mix, and balancing capacity needs, by evaluating a wide range of scenarios using hourly data from PVGIS and GWA, thereby offering deeper insights into issues of system design and performance. These scenarios demonstrate that diurnal storage of less than 0.5 average daily demand is sufficient to satisfy a penetration of 80–90 % of the annual demand, in combination with varying levels of curtailment associated with specific wind-solar mix. However, depending on the resource mix, achieving the final 10–20 % penetration requires applications other than diurnal storage. While some previous studies have observed similar trends in limited scenarios, this work provides broader validation by simulating extensive and diverse scenarios across all major design parameters, confirming that the observed trends are case-independent. More importantly, it links the above system design parameters with system efficiency and demonstrates, for the first time, that an optimal range of these parameters ensures an optimal system efficiency, which forms a multidimensional constraint that is difficult to implement in any technoeconomic modeling tool but provides important boundary conditions for policy and regulation.