Options for change in the Australian energy profile

Abstract

Climate change is occurring largely as a result of increasing CO(2) emissions whose reduction requires greater efficiency in energy production and use and diversification of energy sources away from fossil fuels. These issues were central to the United Nation climate change discussions in Durban in December 2011 where it was agreed that a legally binding agreement to decrease greenhouse gas emissions should be reached by 2015. In the interim, nations were left with the agreement reached at the analogous 2009 Copenhagen and 2010 Cancun meetings that atmospheric CO(2) levels should be constrained to limit the global temperature rise to 2 °C. However, the route to this objective was largely left to individual nations to decide. It is within this context that options for reduction in the 95 % fossil fuel dependency and high CO(2) emissivity of the Australian energy profile using current technologies are considered. It is shown that electricity generation in particular presents significant options for changing to a less fossil fuel dependent and CO(2) emissive energy profile.

Fig. 1

The Australian energy profile for the financial year 2008–2009 in which all quantities are rounded to the nearest PJ. Domestic production and imports are shown to the left for a total of 19 583 PJ once −90 PJ in stock changes and discrepancies are accounted for. Total exports of 13 810 PJ and the domestic energy supply of 5773 PJ composed of 5470 PJ from fossil fuels of which 2413 PJ were used in electricity generation, 162 PJ (together with 7 PJ electricity) in fuel treatment, transformation, and refining, and 2895 PJ was supplied to end users together with 303 PJ from renewable energy sources. The productive domestic end use was 2364 PJ after the loss of 1865 PJ in supply and 1544 PJ in end use

Fig. 2

The sources and efficiencies of electricity generation and supply, and end use in Australia in the financial year 2008–2009. In the left-hand column the primary energy (2413 PJ to give 871 PJ of electricity) in the fossil fuels used is shown in black, that in the biofuels/bagasse and wood (33 PJ to give 10 PJ of electricity) is shown in green as is the 59 PJ of electricity generated from hydro/wind/solar sources. The efficiency of electricity generation from each combustible fuel is shown on the arrows leading to the first blue column to give 881 PJ of electricity at an average efficiency of 36 %. Addition of the 59 PJ from the other renewable sources gives a total of 940 PJ of electricity generated. The second blue column shows the 809 PJ of electricity remaining after losses of 1565 PJ of primary energy and 131 PJ of electricity used in generation, supply, and transmission to give an overall efficiency of 32.5 %. The final column shows the use of 7 PJ of electricity for refining leaving 802 PJ for end users on the grid. All energy quantities are rounded to the nearest PJ

Fig. 3

Five cumulative options for change in Australian electricity generation to decrease fossil fuel use by 53 % and CO₂ emissions by 71 % while retaining an electricity output of 940 PJ (261 TWh) based on the year 2008–2009. Option 1: Current profile. This is the BAU option leading to increasing CO₂ emissions as electricity use grows. Option 2: Efficiency increased to 50 %, increases the efficiency of electricity generation from combustible fossil and renewable fuels to 50 % and results in decreased fossil fuels use while retaining the same renewables use and decreasing CO₂ emissions by 29 %. Option 3: Natural gas only fossil fuel, requires the replacement of other fossil fuels with natural gas while retaining the same renewables use and decreasing CO₂ emissions by 46 % cumulatively. Option 4: Renewable electricity at 20%, increases the use of renewable resources to 20 % while retaining them in the same proportions as in Option 1. This decreases natural gas use with a cumulative CO₂ emissions decrease of 62 %. Option 5: Nuclear electricity at 20 %, generates 20 % of electricity as nuclear electricity while retaining the same renewables use and decreasing natural gas use with a cumulative CO₂ emissions decrease of 71 %