Greenhouse Gas Mitigation: Sources And Sinks In Agriculture And Forestry
- Agriculture and forestry can make a valuable contribution to lowering Australia’s greenhouse gas emissions by reducing their own direct emissions and by increasing the amount of carbon stored in soils and landscapes.
- [Soils] and forests … store large quantities of carbon [— potentially enough] to offset up to 20% or more of Australia’s emissions during the next 40 years.
- Forest plantings [and] reduced land clearing, provide the most immediate, significant, and realisable carbon sequestration opportunity.
- Nearly a third of Australia’s terrestrial carbon is stored in tropical savannas …
[Savanna] fires currently contribute 2–3% of the nation’s total accountable emissions and have an important bearing on rates of carbon sequestration.
- [Sheep and cattle] emit methane as a by-product of digesting feed. …
Mitigation Strategies For Energy And Transport
- Australia has an abundance of clean energy options from which to choose. …
- Renewables are expected to feature more prominently in Australia’s energy mix by the 2020s.
- [Development of coal] carbon capture and storage for base-load power generation … will depend critically on the [carbon] price …
Prolonged uncertainty [over pricing could delay investment] in any technology that may be ‘stranded’ by subsequent policy decisions.
- Energy saving technologies, demand reduction, and distributed power generation will help to lower national carbon emissions.
- Changes in the transport sector will be driven … by oil [rather than] carbon prices.
Electricity may become the transport fuel of choice [supplemented by] LNG gas, diesel, and biofuels.
Hydrogen fuel cells may eventually replace batteries in electric vehicles.
Reducing Energy Demand: The Imperative For Behavioural Change
- The Australian public will have a powerful influence over the pace and extent of climate change mitigation and adaptation strategies and actions adopted by the nation. …
- There is considerable scope for individuals to reduce their own carbon footprint, and there is growing public support for a transition to a ‘green economy’.
- Face-to-face communication and knowledge sharing to overcome the gaps in knowledge are critical.
Agriculture and Forestry
Energy and Transport
Reducing Energy Demand
- Climate Change: Science and Solutions for Australia, 2011.
Helen Cleugh, Mark Stafford Smith, Michael Battaglia and Paul Graham: Editors.
GREENHOUSE GAS MITIGATION: SOURCES AND SINKS IN AGRICULTURE AND FORESTRY
Michael Battaglia, CSIRO Sustainable Agriculture Flagship
[How we] manage our rural lands will have a significant impact on Australia’s future net greenhouse gas emissions.
Reducing emissions from Australian land use
[Agricultural] emissions consist of
- carbon losses due to land clearing and land-use change (36%),
- livestock methane emissions and manure management (43%),
- savanna burning including both naturally caused wildfires and deliberate burning for pasture management (10%), and
- cropping and agricultural soils emissions (11%) …
We can potentially … offset up to 20% or more of Australia’s emissions during the next 40 years [through carbon sequestration.]
[How much can actually achieved depends on] many factors, such as
- carbon pricing and other incentives,
- government policy,
- technology, and
- social attitudes …
[Aside from GHG mitigation] other benefits [include:]
- restoring biodiversity and ecosystem services,
- improving soil productivity,
- controlling salinity and erosion, and
- improving water quality
Unlike … mitigation options [in other sectors e.g. energy generation,] forestry and land-management options do not require major investment in infrastructure.
[Instead, there are other potential tradeoffs such as] lower food, fibre, and timber production and, if unregulated, altered regional water flows.
Maximum rates of afforestation in Australia in recent times have been around 100 000 hectares per year, suggesting it will take around 20 years to achieve 20 Mt of CO2-e per year of abatement potential.
[Carbon] forests need to be managed (and their carbon counted) according to natural cycles of death and decay, including the periodic impact of fire. …
[At] even a modest carbon price (AU$10–20 per tonne of CO2-e), forestry could be a competitive land use across large areas …
Because carbon forests do not need to be near processing facilities, they can be scattered across the landscape, lowering the risk of carbon release by fire, pests, and storms, and spreading their impact on water supplies. …
Trees occupying about 10% of the farm can be used as
- shelter for livestock,
- wind breaks,
- for controlling salinity,
- enhancing native biodiversity, and
- adding to capital value. …
[Afforestation] could achieve significant national carbon sequestration [with] minimal impact on food production, and … many environmental benefits.
Deforestation … has been reduced with recent landclearing restrictions. …
[Tropical savanna] fires currently contribute 2–3% of the nation’s total accountable emissions and [affect] rates of carbon sequestration.
[There] is growing interest in curbing the extent and severity of these fires using Aboriginal early season mosaic burning techniques, which produce cooler, less-destructive fires.
[Additional benefits include:]
- [generating] livelihoods in remote Aboriginal communities,
- [reducing] the risk of wildfires, [and]
- [encouraging] native species …
It may also be possible to increase carbon stocks in stands of managed native forests [through cessation of harvesting activities. …]
[However, a] high level of uncertainty surrounds … the estimates of carbon stocks, the longer term impacts of harvesting and fire, and the [long-term] fate of carbon stored in forests and timber products. …
[Native] forests dominate the carbon and water cycles …
Droughts, fires, pests, and disease … could potentially overwhelm any gains made in carbon storage.
Soil organic carbon and biochar
The amount of organic carbon present in a soil is determined by the rate at which organic matter is added and the rate at which it decomposes.
Organic carbon in soils turns over constantly. …
There are two main ways to build soil carbon: by increasing the amount of organic matter entering the soil or by reducing CO2 losses …
[Reduced tillage] may reduce the rate at which soil organic carbon decomposes.
Past clearing of farmland and tillage has generally led to declines in the organic carbon content of most soil types. …
Minimum tillage and no-till are already practised on much of Australia’s 27 million hectares of cropping land …
[If] such practices were extended across the other 9 million hectares, croplands may offer 2 to 5 Mt CO2-e abatement per year.
Other practices [include:]
- changes to cropping systems (stubble retention, changing crop rotations, increasing frequency of pasture leys, and increasing fertilisation),
- increasing production by incorporating a higher proportion of legumes (nitrogen fixers), and
- reversal of existing degradation (saline, acidic, and eroded land) by planting perennial species …
The biggest gains are likely to come from converting cropping land to secondary forest or pasture.
The 400 million hectares of Australia’s rangelands represent the biggest theoretical opportunity for locking up carbon in landscapes [through] reducing grazing or changes in pasture management.
… 4–50 Mt CO2-e per year [may be attainable nationally.]
At present too little is known to be confident of these estimates.
Biochar is a form of charcoal created by burning organic matter in a closed system under conditions of low oxygen availability.
[The] gases released during the formation of biochar can be captured and used for energy generation.
[The process stabilises the] organic carbon against biological decomposition [converting it into a relatively] longterm carbon storage material …
The most beneficial sources of organic material [are:]
- human wastes,
- forest thinning (or custom-grown carbon forests), and
- agricultural by-products.
[The reduced soil organic carbon levels, soil biological activity, and nutrient cycling would offset any] carbon sequestration gains made through the creation and application of biochar.
The production of [synthesis gas (‘syngas’) or biofuels] has the potential [to] substitute for carbon-polluting fossil fuels.
Additionally, some biochars have been shown to enhance soil fertility [and reduce] fertiliser requirements …
Estimates of sequestration potential from this process in Queensland are around 4 Mt CO2-e per year.
In 2008, this contributed 55 Mt of CO2-e to Australia’s national Kyoto accounts, corresponding to 9.6% of Australia’s total greenhouse gas emissions and the largest component of agricultural emissions. …
Reducing stock numbers [may not be] the most practical way to reduce Australia’s livestock emissions … because most grazing land is unsuitable for other productive uses, this would have an adverse impact on food production and employment. …
[Furthermore,] grazing reduces grass biomass, fire frequency, and competition with tree and shrub seedlings, potentially allowing regeneration of shrubs and trees, which might increase carbon stock in the long run. …
[Measures that could] reduce per animal emissions by 10–20% in the next decade, and perhaps up to 40% in the longer term … include
- dietary manipulation,
- modification of rumen fermentation,
- feedstock quality, and
- selective breeding for reduced emissions.
[Options] that increase animal growth rates and reproductive performance can reduce emissions intensity and increase producer profitability.
[Best-management] practices that reduce emissions per unit of saleable product (emissions intensity) also offer advantages in restoring land condition by removing livestock from marginal or sensitive areas and increasing biodiversity. …
Emissions from manure contribute over 1.5 Mt of CO2-e per year to our national emissions, principally from dairy and piggery sources.
In intensive and large operations, this methane can be captured and used to displace fossil fuel use.
Realistically, two-thirds of these emissions could be abated with appropriate incentives, with additional abatement from avoided fossil fuel use in energy production.
In 2008, agricultural soils contributed 15 Mt CO2-e, principally from nitrous oxide (N2O) emissions associated with the use of fertilisers. …
[Cost savings] and greenhouse gas emissions abatement are possible by controlling inputs of nitrogen fertiliser, with the aim of improving the match between crop nitrogen demand and nitrogen supply. Benefits can be obtained by matching the timing, rate, and method of application …
In many cases, the actions required to reduce emissions through fertiliser use in agriculture are identical to best-practice strategies to maximise the efficiency of fertiliser use and minimise undesirable environmental impacts such as the contamination of waterways.
[Carbon] prices or incentives to store carbon will have to be sufficient to encourage the widespread adoption of carbon sequestration practices by landholders. …
Using our land and modifying our land management wisely can give us time to reduce sources of emissions from other sectors of the economy and may offer some ongoing carbon pollution abatement potential … that reduces the overall cost to the economy of climate-change action.
[The] generation of carbon credits or offsets … has the potential to be a major source of income in rural Australia, allowing landowners to further diversify income streams.
MITIGATION STRATEGIES FOR ENERGY AND TRANSPORT
Paul Graham: CSIRO Energy Transformed Flagship
John Carras: CSIRO Advanced Coal Technology Portfolio
Jim Smitham and Jenny Hayward: CSIRO Energy Technology
Australia has a high per capita emissions intensity and has a higher energy use per unit of GDP than the OECD average …
[Australia's comparative] advantages [include] low-cost fossil fuel and mineral resource extraction and processing industries.
[Its] main disadvantage is large transport distances, both within Australia and to its overseas customers.
[The transport sector] is dependent on oil for 94% of its energy usage. …
The remaining oil is used in the agriculture, mining, and chemical industries.
[Australia] is dependent on coal for 80% of its [electricity] generation. …
For electricity production, Australia has over three times the greenhouse gas emissions per capita than the OECD average …
[For transport —] some 30% higher.
[Modelling] shows that …
- around one-third of the nation’s energy greenhouse emissions savings could be expected to come from energy efficiency plus demand reduction,
- one-third from renewables, and
- one-third from carbon capture and storage.
Major drivers for change, uncertainties and implications
[The path to effective mitigation] is a complex interplay between uncertain technology costs, future energy prices, and policy options.
The main drivers of innovation and [of take-up of new] technologies are
- the cost of petroleum for the transport sector,
- the price of carbon for the power generation sector, and
- the uncertainty of future technology costs. …
Recent projections … suggest a gradual increase in the price of carbon of around 4% per annum over several decades to 2050.
If this rate of increase was built into a cost for carbon emissions … it would imply a gradual, rather than a rapid, shift to new technologies.
Gradual adjustments make the transitions for the economy easier.
Investors need a high level of confidence that a project will be viable …
In the absence of a clear indication of a carbon price in the near term, the only certain policy driver for the sector is the 20% renewables target.
Unless plant costs fall — or electricity prices rise — to reduce the level of investment risk, it is plausible that investment in base-load power generation will be delayed for one to two decades, with consequent energy shortages.
Oil prices, rather than [carbon] emissions, are likely to be the main influence on the evolution of Australian transport technology in the foreseeable future. …
High world oil prices … will be the main signals to shift to fuel and transport alternatives, and these signals are likely to occur within the next two decades. …
Although current oil prices are high enough to encourage significant investment in new oil field production, it is unclear how long new oil production will be able to offset the decline in production from existing oil fields.
The role of innovation
[Potential] mix of Australian clean energy sources for electricity production out to 2050 showing the changes in technology mix to achieve emissions reduction.
CCS = carbon capture and storage
pf = pulverised fuel
DG = distributed generation
[By] 2030 — and with a carbon dioxide price of AU$52 per tonne — wind could be more competitive than the fossil fuel technologies …
[Simulations] of the cost of electricity … for different technologies for two CO2-e prices.
LCOE = levelised cost of electricity CCS = carbon capture and storage
pf = pulverised fuel
O&M = operations and maintenance
Energy and transport technologies
1. Efficiency, demand reduction, and distributed power generation
Energy efficiency …
[The] Federal Energy Efficiency Opportunities Program [has] reported that 199 large companies have identified energy saving opportunities equivalent to 1.1% of Australia’s greenhouse gas emissions, with savings to boilers, furnaces, kilns, chemical processes, and electrical equipment and mobile equipment. …
[Areas] for improvement include the
- building sector,
- commercial air-conditioning,
- residential water heating,
- improved insulation, and
- commercial and domestic lighting …
Demand reduction can be achieved [by] the use of ‘smart agents’ and ‘intelligent grids’. …
[Energy reducing building design considerations include:]
- natural lighting,
- thermal load management via the use of appropriate building materials,
- siting of buildings, and
- the use of shading, breezes, and vegetation.
Distributed power generation seeks to achieve energy savings by generating electricity close to the point of use …
Small generators that burn fossil fuels are more efficient overall and are less greenhouse gas intensive if their waste heat is captured and used locally for heating and cooling.
Combining heating, cooling, and power production can potentially double the efficiency of fuel use.
Small-scale generation is more responsive to local demand and … can achieve greater cost savings overall when the network costs are considered.
[To] achieve a reliable and stable supply from a significant number of distributed generators … the electricity grid will require significant augmentation and capital investment.
2. Renewables and nuclear
Photovoltaic (PV) technologies …
Silicon-based PV technology has developed over the past three decades, with significant gains in [affordability and] efficiency …
Second-generation thin-film PV technologies such as CdTe have been introduced, with higher efficiencies and lower costs for large-scale PV power plants …
[Third-generation] PVs, such as organic solar cells (PV or dye), are early stage technologies that promise rapid and cheap production, but their efficiency is still significantly lower than for silicon units.
Solar thermal technologies [include:]
- domestic solar hot water systems
- ‘trough’ collectors that focus the Sun’s rays along a single axis where the receiver is located and which tracks with the Sun.
They are cheap to make and produce steam at up to 300ºC, which can be used to produce electricity or heat for industry.
- linear Fresnel technology in which the linear receiver is stationary and is heated by tracking mirrors …
- dish collectors that track the Sun and focus the Sun’s rays on a receiver
- ‘heliostat’ and tower collectors that focus the Sun’s rays to a single point to produce very high temperatures (of the order of 1000ºC) to drive chemical processes, and make steam or hot air to run electrical turbines. …
Wind power is currently … being deployed on quite a large scale …
Obstacles … include
- the high capital cost of the generators (driven by strong global demand) …
- power fluctuations,
- the need to store power during calm conditions, and …
- public acceptance.
[Solar] and wind power require the development of cost-effective energy storage facilities to be able to mitigate power fluctuations …
Biomass energy — for electricity or [liquid] fuels …
The best prospects occur when the biomass source is close to the place where the energy is consumed: for example, when the bagasse produced by the sugar cane industry is burned to produce heat and electricity used for sugar refining.
Hydro power has limited large-scale expansion opportunities … due to
- public aversion to the large-scale impacts on river systems,
- limited accessible sites, and
- declining rainfall in the south.
Hot fractured rocks are [being developed as a reliable and low-cost source of] base-load energy …
- current high drilling costs,
- geological uncertainty,
- low relative power efficiencies,
- the amount of water needed to access the heat which is lost in the process, and
- the proximity of the grid. …
Ocean energy — Australia has [some of the best] wave, current, and tidal energy [resources in the world –] especially along the WA, Victorian and Tasmanian coasts.
[The] technologies are still at an early stage in their development and … suffer from
- distance from the grid, and
- uncertainty about long-term maintenance and operational costs.
(p 120, italics added)
Nuclear energy [— barriers to] adoption include
- high capital costs,
- long lead times,
- lack of a trained workforce, and
- current lack of public support.
3. Fossil fuel energy and carbon capture and storage
Carbon capture and storage …
[Oil,] natural gas, and CO2 have been stored naturally in such formations for many millions of years.
- [Pre-combustion capture:]
- Gasification involves reacting coal with controlled amounts of oxygen and water at high temperature and pressure to produce raw syngas.
When combined with syngas processing, the ultimate products are CO2 and hydrogen.
The pressurised CO2 can be separated for storage and the hydrogen burned in special turbines to produce electricity, with water as the only emission.
- Oxyfuel combustion burns coal in a CO2/oxygen mixture with recycled flue gas (instead of nitrogen/oxygen when air is used).
The flue gas is predominantly CO2 [some of which] is removed, cleaned, dried, and pressurised for geological storage. …
- Gasification involves reacting coal with controlled amounts of oxygen and water at high temperature and pressure to produce raw syngas.
- Post-combustion capture involves reacting the flue gas … with a chemical solvent to capture the CO2 before the flue gas is emitted.
The chemicals are regenerated and reused.
The [concentrated] CO2 … can be cleaned, dried, and pressurised for storage.
[Postcombustion capture] can be retrofitted to existing coal plants.
[Some] elements of the technology chain currently exist [however, there has yet to be a] demonstration of an integrated process at a commercial large-scale power station.
[Other] ways to ['lock up' CO2 are also] being investigated:
- Mineralisation, where CO2 is reacted with naturally occurring minerals to form very stable carbonate rocks that can be stored in mines, or even used in building materials.
- Algal cultures, where the CO2 and added nutrients are used to grow algae with a high lipid content for the production of biodiesel for transport fuels …
[Fossil fuel based] developments … include:
- Gas, which is seen largely as a ‘transitional fuel’ for peak power generation …
[Natural] gas is in high demand worldwide [resulting in] fluctuations in supply, demand, and price.
[Rapid] development of coal seam gas [is proceeding] in Australia …
- Hybrid technologies …
- coal-fired power supplemented by solar thermal energy [and]
- solar/gas systems.
- [More] efficient ways of converting the chemical energy in coal to electricity. …
- large diesel engines fired with specially prepared slurries of fine coal and
- the direct carbon fuel cell.
4. Transport sector
Over the next 10 years … diesel, electricity, liquefied petroleum gas (LPG), and natural gas (particularly in freight) will all increase their share of the transport fuel market …
[Beyond] 2020, advanced biofuels [and synthetic fuels are] are expected to come into wider use once production infrastructure has had time to scale up
How widely they are adopted will depend on primary fuel prices and greenhouse gas emission targets. …
Biofuels could … supply around one-quarter of transport needs without having a significant impact on food production or soil nutrient quality.
In the short term, ethanol and biodiesel blends will continue to be available, using crop wastes, tallow, and cooking oil.
[From] around 2020-25, the principal future sources of biofuels will be lignocelluloses and plant oils (from crop stubble and forestry residues or special energy crops such as algae) …
Biofuels are not completely emission-free because … they use fossil fuels in the biomass feedstock production process. …
LNG is a niche fuel more likely to suit long-distance transport operators, because the cost of converting vehicles is high and can only be re-couped by significant fuel savings. …
Electricity may emerge as the … fuel of choice for the majority of motorists and transport operators in the longer term.
It is expected that the share of vehicles drawing electricity from the grid will increase … to at least 10% by 2030.
As hybrid vehicle technology matures, it will enable drivers to achieve 80% of their (city) mileage using electricity: using fossil fuel only for the 20% of trips that are outside battery range.
The rate of electrification will depend … on world oil prices relative to electricity prices and battery costs.
[Successful] electrification of the transport fleet will [depend on the large scale] introduction of CCS and/or renewables.
[Synthetic] fuels made from coal and natural gas [would] involve large greenhouse gas emissions [without] carbon capture and storage …
Synthetic fuel plants also suffer from the same investment risks as large-scale coal power generation, being multi-billion-dollar investment projects dependent on uncertain revenue drivers …
Hydrogen … can be made from fossil fuels or by splitting water into … hydrogen and oxygen.
[The] development of a cost-effective vehicle fuel cell to convert hydrogen into electrical power is lagging behind other sources of power …
In the medium term … the batteries in an electric vehicle [could be replaced] with a hydrogen fuel cell.
The availability of hydrogen fuel could be fairly easily achieved by locating small units that use electricity to split water into hydrogen and oxygen at service stations, car parks, and elsewhere.
Australia’s greatest need is for low-emissions technologies that are competitively priced, resilient, and flexible enough to cope with a range of possible future energy challenges and demands.
Technologies whose costs fall quickest will tend to predominate, even though they may be more expensive at present.
All options are still in the mix for a future energy system [and] it will be important … to identify the most advantageous combinations of solutions.
Australia has more energy options than almost any other country …
REDUCING ENERGY DEMAND: THE IMPERATIVE FOR BEHAVIOURAL CHANGE
Peta Ashworth: CSIRO Energy Transformed Flagship
To date … the actions of the majority of Australians to reduce their personal greenhouse gas emissions have been minimal.
To achieve a significantly greater rate of change will require a major alteration in public attitudes.
Australian attitudes to energy technologies
[Research] has established that the Australian public:
- agrees that climate change is an important issue to Australia …
[In] the 18–25 age group [82% agree] that global warming has been established as a serious problem and immediate action is necessary, or that there is enough evidence that global warming is taking place and some action should be taken …
- still has limited knowledge about the causes of climate change and what can be done to mitigate it [e.g.] many people [don't] see the link between their own energy consumption and greenhouse gas emissions …
- can be quite concerned and depressed about the enormity of the problem
- recognises there is a role for government, industry, and themselves in responding to climate change
- is willing to pay for necessary changes.
Most participants … indicated that they would be prepared to pay up to AU$50 more a quarter for electricity.
A significant number already subscribe to green power, ranging from 49% in Brisbane to 13% in Perth.
Changing individual behaviour
[Research has highlighted] the importance of face-to-face communication and knowledge sharing to overcome the gaps in knowledge about the issue and technologies. …
Energymark works by engaging those citizens who are determined to do something to reduce their own personal carbon footprint, to work with CSIRO to convene a group of friends, family, or work colleagues to contemplate the topic of climate and energy over an 8- to 12-month period.
In the first 12-month trial carried out [in] Newcastle, New South Wales, 172 citizens managed to reduce their collective greenhouse gas emissions by 27%.
[Average] household electricity consumption … fell from 14 420 to 9029 kilowatt hours, with participants managing to cut their power use by 35% …
[Think of your carbon footprint] in terms of domestic garbage bags, each holding 100 g of CO2 (or its equivalent). …
(p 131)Adapted from The CSIRO Home Energy Saving Handbook
Small steps with a big impact Bags avoided Dry clothes on a line 3000 Turn off spare fridge 4000 Replace incandescent lights with low-energy bulbs 7000 Change to cold water clothes washing 8000 Eat foods with lower carbon content 10,000 Improve heating and cooling of home up to 12 000 Reduce purchases by 10% 14,000 Grow your own vegetables and compost waste 17,000 Car pooling and cycling 20,000 Smart investments Buy an energy efficient fridge or washing machine 6,000 Go for low-wattage lighting 10,000 75% of your journeys by bike or public transport 20,000 Adopt passive heating and cooling up to 24 000 Use solar, gas, or heat pump for hot water up to 34,000 Replace electric heaters with natural gas up to 80,000 Giant leaps Buy a hybrid car 19,000 Base house design on the surrounding environment up to 37,000 Install solar, wind power, or micro-hydro for domestic electricity up to 50,000
Target audiences and processes
[The] four main audience groups are:
- influential stakeholders, such as politicians, media, NGOs, chief executives …
- the general community …
- the education sector — not only schools and universities, but also through museums, science centres [— and]
- communities or groups affected by particular energy projects.
…‘Carbon Kids’ [is] an educational program developed by CSIRO Education to enable primary and secondary school classes to work together to achieve reductions in their carbon footprint.
[Citizens’ panels can] provide an excellent framework for tackling complex issues that can be applied in various contexts at the local, national, or international level. …
The public has made it clear in numerous polls that it wants action, but it is also looking to others in positions of influence to lead it in what to do and which technologies to support. …
Action on climate change will only be successful through the combined efforts of government, industry, and the public at large.