Ore-Chestrating Net-Zero: A Techno-Economic Comparison of Lithium Batteries and Vanadium Flow Batteries in a Western Australian Mine Site
Authors: Vijayaratnam Pujith Rajaguru Senapathy , Menictas Chris , Skyllas-Kazacos Maria 
Published: December 2024

Background: Remote mining operations in Western Australia are faced with the challenge of transitioning to renewable energy solutions to achieve net-zero carbon emissions by 2050. A promising strategy for these off-grid sites is to integrate wind and solar energy with battery storage systems, reducing their reliance on fossil fuel-based energy sources like natural gas turbines.

Objectives: This study investigates the feasibility of using two types of battery energy storage system – Lithium-Ion (Li-ion) and Vanadium Flow Batteries (VFB) – in off-grid Western Australian mine sites to achieve the net-zero emissions reduction target. Li-ion batteries possess the advantages of higher energy density, higher efficiency and widespread commercial availability whilst VFBs offer scalability, long cycle life and inherent safety features.

Methods: A microgrid model was developed using HOMER (Hybrid Optimization of Multiple Energy Resources) Pro version 3.17.1. Key economic parameters – including the capital, operations and maintenance costs of wind turbines, photovoltaic panels, natural gas turbines, converters and batteries – were integrated into the model.

Results: For each storage configuration, the simulation results which yielded the lowest discounted cash flows relative to a configuration in which only natural gas turbines were used to meet 100% of the projected load may be seen in Figure 1. The 4-hr Li-ion batteries (80% DOD) had the lowest initial capital costs for both the 0% and 10% capacity shortage simulations of all cases which met the minimum renewable fraction criteria. This was because of the higher round trip efficiency of the Li-ion batteries when compared to VFBs and the high DOD when compared to the 60% DOD Li-ion simulations. These factors resulted in fewer MWh of 4-hr Li-ion packs being needed to meet the projected load. However, the 80% DOD also resulted in the Li-ion batteries needing to be replaced more frequently than the 60% DOD Li-ion batteries, as shown by the sudden drops in the Total Discounted Cash Flow plot. By the end of the 20-year simulation period, the configurations supported by 10-hour duration VFBs yielded the highest cash flow increase due to their longer lifespan.

Figure 1. Cumulative cash flow over a 20-year period for a Western Australian mine site microgrid implementing Li-ion batteries and VFBs.

All storage options dramatically reduced the levelised cost of energy (LCOE) when compared to the ‘No Storage’ configurations, as shown in Table 1. This was due to a greater amount of solar and wind power generation being required when no storage was present, as shown in the Total Power Capacity results in Figure 1. These results also revealed that when storage was present, the simulations which produced the lowest net present cost had no wind power generation. This was due to a significant overlap in the periods of peak wind and solar generation in the region and the relatively low projected cost of solar generation. The results also showed that allowing a capacity shortage of 10% dramatically reduced the LCOE and cumulative costs associated with each storage type; however, further analysis is needed to assess the impact of shutting down the mine site during these shortage periods.

Table 1. Levelized cost of energy associated with each storage configuration over the twenty-year simulation period.

System

Levelized Cost of Energy (AUD/kWh)

0% Capacity Shortage

10% Capacity Shortage

Natural Gas Turbines Only

(0% Renewable Fraction)

0.095

0.089

Solar + Natural Gas Turbines + Wind + No Storage

(50% Renewable Fraction)

0.180

0.143

Solar + Natural Gas Turbines + 4-hr Li-Ion Packs (60% DOD)

(50% Renewable Fraction)

0.124

0.112

Solar + Natural Gas Turbines + 4-hr Li-Ion Packs (80% DOD)

(50% Renewable Fraction)

0.119

0.109

Solar + Natural Gas Turbines + 4-hr VFB Packs (80% DOD)

(50% Renewable Fraction)

0.108

0.101

Solar + Natural Gas Turbines + 10-hr VFB Packs (80% DOD)

(50% Renewable Fraction)

0.109

0.099

Figure 1