Anita Talberg, Dr Alex St John, Science, Technology, Environment and Resources and Kai Swoboda, Economics
The bulk of Australia’s greenhouse gas emissions reduction efforts are likely to come from the energy sector through improved efficiency, renewable energy, and potentially carbon capture and storage. However, the land sector can also make a contribution, mainly through changed farming and forestry practices.
Australia’s greenhouse gas inventory
Most of Australia’s greenhouse gas emissions result from energy use, as the table below shows. The largest single category of energy use is the generation of electricity, while agriculture is also a significant contributor, accounting for almost as much as transport. This brief considers some technologies and processes that could be used to reduce Australia’s emissions.
Australia’s net emissions by sector, year to December 2012
Share of 2012 emissions
|Energy – Electricity
|Energy – Stationary energy excluding electricity
|Energy – Transport
|Energy – Fugitive emissions
|Afforestation and reforestation
Source:Quarterly Update of Australia’s National Greenhouse Gas Inventory, December Quarter, 2012.
Reducing emissions from energy use
There are three ways to reduce greenhouse gas emissions from energy use. The first is to use less energy (see brief on energy efficiency). The second is to use energy sources that do not emit greenhouse gases (see brief on renewable energy). The third is to capture the greenhouse gases generated before they are released into the atmosphere. This last option is known as carbon capture and storage (CCS).
CCS removes carbon dioxide (CO2) from waste gas streams (like a power station exhaust) and then stores the CO2 underground in suitable geological formations. CCS is not envisaged for vehicles, but is particularly suitable for emissions that are produced from large power plants burning coal, oil or natural gas (methane). It could also be incorporated in some industrial processes.
Two CCS projects are under development in Australia: the South West CO2 Geosequestration Hub, near Collie in Western Australia, and the CarbonNet project near the La Trobe Valley in Victoria. If commissioned, both projects will capture emissions from local industry and sequester them underground.
Globally, only eight large-scale CCS projects were in operation in 2012 and none of these is similar to the two proposed Australian projects.
CCS can be costly, especially where it is retrofitted onto existing coal and gas power stations. It is not yet clear whether CCS will be economically viable in the long term. In 2011, the Commonwealth Science and Industrial Research Organisation (CSIRO) estimated that a carbon price of between $70 to $90 per tonne of CO2 would be needed for CCS to break even, which is much higher than the 2013–14 price of $24.15 per tonne. With no carbon pricing, CCS’s cost-benefit balance appears even less appealing.
Reducing emissions from waste
When household waste is deposited and piled up over a period of time, the organic components eventually begin to decompose. Depending on a number of factors, including the type of waste and the climate of the area, the breakdown of the waste produces a mix of gases. The one of greatest concern in this context is methane, because it is a more powerful greenhouse gas than CO2. Activities that reduce emissions from landfill include capturing the methane, which can be burnt to generate electricity or piped to homes; flaring the methane (that is, burning it so that it does not remain in the atmosphere); and recycling or treating some of the waste, so that it does not accumulate to produce methane.
Reducing emissions from the land sector
The gas CO2 in air is just one form of the element carbon. Carbon also exists in large quantities in the ocean, the soil and all living things (especially trees). Through the process of photosynthesis in plants, CO2 is pulled out of the air and the carbon slowly circulates through plants, animals, soil and back to the atmosphere. Soil also absorbs and retains carbon. According to the Wentworth Group of Concerned Scientists’ paper, Optimising Carbon in the Australian Landscape, the total stock of carbon in the Australian landscape is approximately 100 billion tonnes. National carbon emissions are in the realm of 0.5 billion tonnes per annum.
Certain factors can influence how effective the landscape is at storing carbon. For example, a short-to-medium term decrease in rainfall can cause reduced growth in plants. This means less daily photosynthesis and, therefore, reduced carbon absorption. Extreme events, such as bushfires, floods and droughts, can also have significant effects—bushfires, for example, release CO2.
Carbon absorption by the biosphere is also known as carbon sequestration. Farmers and landholders can take steps to maximise carbon sequestration or to minimise carbon emissions. In the farming sector examples include:
- zero-tillage farming, where organic matter such as crop residues is left undisturbed to add carbon to the soil
- cover-cropping, in which another crop is planted alongside the yield crop to improve soil quality and add carbon-rich organic matter to the soil
- grazing management to reduce emissions from livestock and
- the use of biochar, which is charcoal made from plant material and agricultural waste. It is produced as an additive to soils, mainly to improve nutrient retention and carbon storage.
Generally, improving carbon retention in farming improves productivity, albeit at some economic cost. The problem with managing carbon sequestration in the farming sector is that it is difficult to monitor, assess and verify. Emissions reduction efforts in forestry are less problematic in this sense. Some possible activities include reducing land clearing, particularly avoiding deforestation of established outback vegetation; allowing vegetation regrowth, especially native vegetation in previously cleared land; and changing fire management practices towards early dry season burning.
The Carbon Farming Initiative
Through the Carbon Farming Initiative (CFI), Australia became the first country to establish a scheme for farmers and landowners to earn carbon credits for activities that absorb or retain carbon. The credits can be sold to individuals or businesses wishing to offset their CO2 emissions. The CFI can be linked to the Australian emissions trading scheme (ETS), allowing landholders to participate in carbon trading, but an ETS is not essential for the CFI. The CFI has bipartisan support. The Coalition Government plans to expand the scheme to include activities outside the land sector, such as energy efficiency projects. An emissions reduction fund will pay farmers for approved projects.
A Talberg, The basics of biochar, Background note, Parliamentary Library, Canberra, 10 September 2009.
Nous Group, ‘Outback carbon: an assessment of carbon storage, sequestration and greenhouse gas emissions in remote Australia’, report to The Pew Environment Group-Australia and The Nature Conservancy, July 2010.
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