The potential of variable speed diesel application in increasing renewable energy source penetration

Integration of renewable energy source (RES) generation to displace diesel generation can present clear economic, environmental and social benefit. While low level RES integration is relatively easy to achieve, both the cost and complexity escalate as systems target increasing RES penetration. A key barrier to greater RES penetrations remains the inefficiency of diesel generation to operate at low or partial loading. To achieve low or partial loading, conventional fixed speed diesel technologies must rely on prescribed purge routines, which serve to increase emissions intensity and fuel consumption. Fixed speed constraint remains the primary barrier to increased engine flexibility and improved partial load efficiency. This paper investigates redesign of the diesel generator to achieve variable speed operation. A suitable design basis is developed, with laboratory testing used to validate unit performance, ahead of economic evaluation. Economic modelling is presented to explore the improve engine flexibility, required of hybrid diesel applications. Variable speed application is shown to reduce diesel fuel consumption by up to 40% in comparison to conventional hybrid diesel applications.