Evaluating the economicsHarvest residues from hardwood and softwood plantations and native forests are considered to be a major potential source of biomass that can be used for energy and fuel.
- growing forests
- harvesting and chipping
- plant growth rates
- availability of substitutes or product (biomass) replacement e.g. woodchip for crop residues
- transport costs (distance, mode of transport, scale of transport loads, pre-treatment potential, fuel)
- fit for purpose of the biomass (e.g. specific plants oils)
- import potential of pulp as a precursor to transformation
- the scale of the value add by the biorefinery (e.g. high value chemicals vs. energy vs. commodity chemicals).
- energy demand
- interest rate
- moisture content
- transport distance
- truck payload.
BenefitsPlantations can be integrated into farm operations, and can be a form of farm forestry. Farm forestry can be a tool of land management, ensuring that agricultural land is both productive and kept in good condition. Plantations can also be integrated into a range of different land uses. How forest plantations affect agricultural land and water availability is discussed in Chapter 5 of the 2011 report of an inquiry into the future of the Australian forestry industry, Seeing the forest through the trees [PDF, 4.5 MB]. Careful siting of plantations in the landscape can maximise timber production while minimising impacts on catchment water yield, according to a CSIRO submission to the forestry report. The benefits of farm forestry, both on-farm and for the local environment, according to the report, fall into three categories: 1) Land and water quality benefits
- improving biodiversity and ecology
- reducing windspeed
- preventing and mitigating wind erosion
- protecting crops and providing shelter for stock
- producing seed and controlling pests
- reducing evaporation
- preventing and mitigating water erosion
- addressing excess groundwater and dryland salinity
- preventing and mitigating land degradation
- sequestering carbon.
- opportunity for diversification
- risk management
- longer rotation crops for superannuation (more than 20 years)
- biofuels – such as biodiesel, methane or ethanol
- biomass – as direct fuel, such as for combustion
- carbon sequestration.
- using land profitably
- achieving catchment targets for increasing native vegetation
- conserving biodiversity
- combating salinity and erosion
- protecting water quality and mitigating some of the impacts of climate change.
- native forest regrowth
- wood-processing residues.
Supply chainForest biomass supply chains have been well defined and researched in Europe and are operating effectively to convert forest biomass to commercial products—including an alternative energy source. Work is needed to adapt these systems to Australian forest operating conditions. The supply chain is a particular barrier for producers of harvest residues to be able to supply power stations for co-firing. This report by AgirFutures, Facilitating the adoption of biomass co-firing for power generation, looks specifically at these barriers. There are barriers for producers of residues from agriculture, agroforestry, forest plantation and native forests. The report also provides information on supply chain logistics and costs with specific concern for supplying power stations with the residue for co-firing. AFORA’s freely available industry bulletins and reports and industry tools also offer information on supply chain.
Growing a plantationPlantations must be carefully and actively managed over their life-cycle to produce particular timber and wood-products: this management is commonly referred to as ‘silviculture’. There is considerable silvicultural expertise in Australia, but, as discussed in Chapter 8 of the 2011 Australian Government report, Seeing the forest through the trees [PDF, 4.5 MB], Australia relies on foreign-trained forestry professionals. The length of time a tree is grown before being harvested is commonly referred to as the rotation length. A plantation goes through a cycle of planting, growing, harvesting, and then replanting. The length of time between planting and replanting may be from 10 years up to 70 or 80 years. This is commonly referred to as the ‘rotation length’. Both softwoods and hardwoods can be grown for short- and long-rotation: in general, short-rotation (perhaps 10 to 15 years) suits trees that are to be chipped or pulped, and long-rotation (more than 20 years) suits trees that are to be grown for sawlogs. The pros and cons of short- and long-term rotations, in the context of Australia’s timber and wood product needs, are described in Chapter 5 of Seeing the forest through the trees [PDF, 4.5 MB].
Harvesting and transporting residueThe method of harvesting trees can have a large affect on the costs and benefits of using plantation residue for biomass production. Bioenergy Australia’s 2012 publication, Bioenergy in Australia: Status and Opportunities [PDF, 9.1 MB], reviews methods and options for:
- drying biomass fuel.
- truck configuration
- road grade, width, surface material
- horizontal curve radius, and vertical alignment.
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