Session: 04-02: Research for the Clean Energy Transition II

Paper Number: 137665

137665 - Economically Sustainable Mini-Grid Development in Sub-Saharan Africa: Demand Insights and Operation Strategies 

Abstract: 

In Sub-Saharan Africa, where electrification is a significant challenge, mini-grids' emergence offers a promising opportunity for rural areas to access electricity. However, it's challenging for developers to accurately anticipate electricity demand for mini-grids, which often leads to system oversizing and complicates both their economic sustainability and the progress of regional electrification. This study focuses on solar-battery mini-grids, exploring the electricity demand and project economic sustainability. The data used in this study encompasses hourly electricity load from over 2000 domestic customers within 25 mini-grids in rural Northern Uganda, for one entire year. Analysis of load data combined with satellite imagery revealed that these images could qualitatively suggest per-customer consumption in mini-grids. Traditional domestic building structures typically correlate with lower per-customer usage, while modern material roofs are often linked to higher consumption per customer.

The study aimed to initially identify the most beneficial load profiles for mini-grids. Identifying these demand-side profiles allows a directed approach to developing strategies that improve the economic sustainability of mini-grids. Therefore, an energy system design model was developed, inputting mini-grid electricity load data to simulate hourly energy dispatch. This model aims to minimize system costs, with its output determining the solar and battery capacities. The simulation results highlight two key characteristics. The daily peak-to-average load ratio is emphasized as the first key metric, indicating a preference for constant daily consumption that avoids the need for oversized solar capacity and extensive multi-day storage for extremely high-demand days. The daytime load ratio is the second crucial metric for an ideal load profile. It emphasizes the advantage of meeting more energy needs during periods of solar availability, thereby reducing reliance on storage systems.

Guided by demand-side insights, the study developed strategies to improve mini-grid sustainability. Firstly, to enhance the daily peak-to-average ratio, load shedding, reducing power supply on extremely high-demand days, was considered a viable strategy. The model quantified the benefits of load shedding: shedding 1% of total electricity could increase the internal return rate (IRR) by 9% on average across the 25 studied mini-grids, while 5% shedding could boost it by 20%. An alternative to load shedding is integrating diesel generators to manage high-demand days, without compromising system reliability. Secondly, the introduction of Productive Use of Energy (PUE) into the mini-grids, exemplified by the installation of 20 grinding machines, and the subsequent collection of a year's operational data, revealed a 10% increase in the daytime load ratio for the mini-grids involved, demonstrating PUE's impact on altering load profiles. This enhancement of PUE also resulted in an average 9% increase in the mini-grids' IRR. Lastly, to address system oversizing, this study advocates for incremental capacity building based on demand growth. A method was applied to model ten-year demand growth projections for the mini-grids. It was found that beginning with small capacities and upgrading every two years in response to demand growth is advantageous compared to a singular design for a decade. This approach offers a more adaptable capacity planning strategy in mini-grid development.

This study presents an in-depth analysis of electricity demand and sustainable development of mini-grids in rural Sub-Saharan Africa, offering innovative strategies for demand management and capacity building to improve the economic sustainability and scalability of these essential energy solutions.

Presenting Author: Yuezi Wu Columbia University

Presenting Author Biography: Yuezi Wu is a fifth-year doctoral candidate at Columbia University with a research focus on energy system modeling and analysis, currently in the context of Sub-Saharan African mini-grid systems.

Authors:

Yuezi Wu Columbia University
Vijay Modi Columbia University