Economic Rationalization of Energy Storage under Low Load Diesel Application

Globally diesel generator sets account for the majority of generation into remote and off-grid power systems. While diesel generation has proven to be a reliable and accessible technology, its downside involves the expense and environmentally emissions linked to diesel fuel consumption. In response diesel generation alternatives are becoming available and cost competitive, via the integration of renewable energy technology (RET). Hybrid power systems (HPS), those adopting both diesel and RET are increasingly employed to reduce cost and environmental emissions. As RET penetration increases within HPS a potential conflict arises, with diesel generation unable to lower output below minimum load set points. These load set points are predetermined to ensure engine efficiency and reliability. Under medium to high renewable penetration, diesel load set points compete with renewable generation to produce surplus energy. This surplus energy must be absorbed by the system. Various ancillary technologies, such as demand management, energy storage and dump loads can perform this role; however such technologies are expensive and complex. This paper introduces low load diesel (LLD) as one solution to minimising surplus generation within HPS. Economic and power modelling is used to explore removal of energy storage (ES) under LLD application. Model validation, undertaken against both kW and MW scale operational diesel generator data sets is referenced to support the conclusion, that LLD is cable of reducing both system establishment and operational costs for medium to high RET penetration HPS.