Techno-economic and environmental analysis of a hybrid power plant

Abstract

This thesis presents a model to optimise the operation of a small-scale, grid-connected, hybrid power plant in deterministic and stochastic frameworks. The model minimises the total cost of supplying electricity from a combination of solar PV, battery storage, a gas fuelled reciprocating engine generator and network delivered electricity, while satisfying several technical and environmental constraints.

The performance of the hybrid plant is first examined in a deterministic framework while considering a range of carbon abatement targets and different types of electricity and gas tariffs. This analysis considers two sets of studies. First, a secondary school in Victoria, Australia is used as a case study. Second, a parametric study that represents a wide variety of different types of consumers. It is found from both the studies that grid-connected hybrid power plants can deliver dispatchable electricity with deep carbon abatement for a low to moderate added costs relative to grid-delivered electricity. For example, in the case study, the levelized cost of electricity increases by $0.03/kWh while achieving an abatement target of 80% relative to grid-delivered electricity costs.

The deterministic model is then extended in two ways: first, by incorporating a demand response model where the consumers are able to shift their peak demand, and second, by including power-to-gas options that can displace the fossil fuel to meet a heating load and run the internal combustion engine. Demand response results in a reduction of total costs from both avoided network charges and reduced hybrid plant investment. However, demand response never displaces the optimality of hybrid power plants. Power-to-gas options are only found to be plausibly economic for areas where electricity and gas grids are not available, and hence the cost of the delivered fuel is high relative to typical, urban pricing.

Finally, for the stochastic analysis, a multi-stage model with generation expansion is developed where the performance of the plant is examined with short time scale, operational uncertainty in solar irradiation and demand. These forms of operational uncertainty are observed to increase operating and planning costs significantly via larger hybrid component capacities that can guarantee energy availability at all times. A comparison of deterministic and stochastic configurations of the plant shows an increase in total costs of approximately 15% when such operational uncertainties are considered.