Operational and economic feasibility of 100% renewable electricity scenarios for Australia

Abstract

This thesis examines scenarios for 100% renewable electricity (RE100) in the Australian National Electricity Market (NEM). If Australia is to achieve its target of reducing carbon emissions to 80% below 2000 levels by 2050, one of the scenarios considered in this thesis may become reality. In this work, simulations of RE100 based on conservative assumptions have been developed that meet actual hourly electricity demand in the NEM geographic area in 2010. The system is based on commercially available technologies: concentrating solar thermal (CST) with thermal storage, wind, photovoltaics, existing hydro and biofuelled gas turbines. Estimates of renewable generation are derived from satellite observations, weather stations, and actual wind farm outputs. A genetic algorithm is used to find the lowest cost scenarios using technology costs for 2030 projected by the Australian Government in 2012. Constraints ensure that reliability is maintained with existing hydroelectricity generation and limited bioenergy consumption.

A range of RE100 systems are found to meet the NEM reliability standard. The principal challenge is meeting peak demand on winter evenings following overcast days when CST storage is only partially charged and wind speeds are low. The lowest cost scenarios are dominated by wind power, with smaller contributions from photovoltaics and dispatchable generation: CST, hydro and gas turbines. The annual cost of RE100 is compared with the projected costs in 2030 of four fossil fuel scenarios. The four scenarios, based on the least cost mix of technologies to meet 2010 demand, are: (i) a high-carbon scenario based on efficient use of coal; (ii) a medium-carbon scenario utilising gas-fired combined cycle gas turbines (CCGTs) and open cycle gas turbines (OCGTs); (iii) coal with carbon capture and storage (CCS) plus OCGT; and (iv) CCGT with CCS plus OCGT. Sensitivity analysis of the results to carbon prices, gas prices, and projected CO2 transportation and injection costs shows that only under a few combinations of costs can any of the low- or medium-carbon fossil fuel scenarios compete economically with RE100 in a carbon constrained world.

It appears possible to reliably supply the NEM using very high penetrations of available renewable energy (RE) technologies with the RE resources of Australia. Furthermore, RE100 is not necessarily more expensive than other low- or medium- carbon options to achieve deep cuts in electricity sector emissions, and offers a lower risk pathway.