Evaluating the economics
- the capital expenses of land acquisition
- plantation establishment
- operational costs include mechanical harvesting; fertiliser and weed control, pests and diseases
- crushing plant construction
- transporting raw oil to a plant for further processing to biodiesel or aviation fuel.
|Cost Category||Scenario A||Scenario B|
|land $/ha over 40 years||Oil Cents/litre||land $/ha over 40 years||Oil Cents/litre|
|Capital (excludes value of land)|
|Establishment of site, planting of trees, crushing plant, machinery||9,384||6.00||9,384||24.00|
|Foregone net returns from alternative land use (e.g. grazing)||656||0.42||656||1.68|
|Machinery – tractor, implements (fuel, oil, parts, repair and maintenance)||1,128||0.72||1,128||2.88|
|Fertiliser and mulch||3,975||2.54||3,685||9.42|
|Control and management of weeds, pests and diseases||2,237||1.43||2,237||5.72|
|Crushing seeds to extract oil||448||0.29||593||1.52|
|General repair and maintenace||267||0.17||267||0.68|
|Power, fuel and oil||347||0.22||347||0.89|
|Administration and wages of manager and staff||6,786||4.34||6,786||17.35|
|Total costs less carbon||32,445||20.74||30,506||78.01|
|Equivalent Annual Value – Total Costs ($/ha/year)||2,677||2,532|
BenefitsPongamia is suited to the northern tropical and subtropical regions in Australia and can be grown in marginal conditions. As a legume, it produces its own nitrogen thereby displacing approx $200 per hectare/pa of nitrates applied as compound fertiliser. Decreased requirement of fertilisers and reduction of cultivation results in lessening of potential soil and chemical runoff. Research shows pongamia’s potential for increasing Australia’s current low level of plant oil production using a non-food crop [PDF, 2.5 MB]. Pongamia seeds contain oils and fatty acids. Pongamia oil has traditionally been used for lanterns, cooking stove fuel, medicines, fodder, beautification, shade, and environmental protection and is currently of major interest for biodiesel production and aviation fuel. Starch from the meal is also suitable for ethanol production. Other useful products from Pongamia trees include:
- Wood, which has been used for stove top fuels, poles, and ornamental carvings
- Bark, which has been used for paper pulp, twine and as a medicine to reduce swelling of the spleen
- Flowers, which are considered good sources of pollen for honey bees, and have been described as having anti-diabetic properties
- Leaves, which have been used as cattle fodder, as an infusion to relieve rheumatism and coughing, as an extract to treat itches and herpes and as a source of poison used by Australian Aborigines for fish spears
- Oil extracted from the seeds, which has been used as lipids for commercial processes, as an ointment for skin diseases, as a liver medicine, as a lamp fuel in India, and for the production of biodiesel (see below)
- Seed cake leftover after oil extraction, which has been used as ‘green manure’ as it is rich in protein and nitrogen.
SupplyingTo produce an efficient biomass, it is critical to minimise the supply chain and delivery costs of the oil to the refinery.
A model for growing Pongamia trees and harvesting, crushing and transporting the oil from its seeds to a refinery is described in the collaborative study Bioenergy in Australia: Status and opportunities [PDF, 9.1 MB], published by Bioenergy Australia in 2012. The study also outlines, potential markets for by products from the oil extruding process. Pongamia meal (also known as karajin cake) has been used successfully as green manure, a natural pesticide and a fungicide. There has also been extensive research into finding ways to use Pongamia meal as livestock feed however this has been less successful due to the cake being highly unpalatable. The University of Queensland are also investigating the potential to develop and establish new types of production systems for Pongamia, as well as the value chains – for example for conversion of oil to aviation fuel. The potential exists for exploring production systems combining Pongamia plantations, grazing and carbon farming which could provide enterprise diversification, reduction of risk, and reduced GHG emissions for the grower.
GrowingPongamia trees have a mature height of 10 to 15 metres. They prefer humid tropical and subtropical climates. In Australia, Pongamia are found in northern tropics and subtropical east coast ranging from the coastal fringe around Darwin through Cape York and as far south as northern NSW. Records further inland are from locations along major rivers including the Wenlock, Archer and Holroyd Rivers in the Cape York area, and the Norman River in the Gulf of Carpentaria. Origin Energy owns and operates the largest commercial trial site (300 ha) near Roma in central Queensland. The crop consists of 170,000 trees, which are irrigated with treated Coal Seam Gas water from the Spring Gully reverse osmosis treatment plant. Field trials have also been conducted to measure the growth of Pongamia in south-east Queensland, Western Australia and the Northern Territory. A Common View of the Opportunities, Challenges and Research Actions for Pongamia in Australia [PDF, 2.5 MB], published in Bioenergy Research in 2012, provides a comprehensive review of these trial’s results with regards to:
- Optimal rainfall
- Critical high and low temperatures
- Frost tolerance
- Suitable soil conditions
- Fertiliser application
- Best practices for managing pests, diseases and weeds.
After that period sheep can be introduced into the plantation to manage the grasses and weeds. This will in turn provide a secondary income from the plantation (Section 10.6.5 of Bioenergy in Australia: Status and opportunities [PDF, 9.1 MB], published by Bioenergy Australia in 2012). Table 2 is adapted from A Common View of the Opportunities, Challenges and Research Actions for Pongamia in Australia [PDF, 2.5 MB]. It shows that pod production starts around 4 to 14 years of age.
Trees can produce anywhere from 0 to 30 kg of seed each year which can be stored up to 12 months. Growers with trees that yield 20 kg of seed per year can expect to 7 tonnes seed per hectare per year on the basis that 350 trees are planted per hectare. Table 2. Summary of reproductive and yield variables based on Australian observations to date.
|Variable||Unit||Range based on all observations in Australia||Average|
|Time to reproductive maturity||Years||4 to >14||5 years|
|Full development of seeds||Months||10-11 months||10 months|
|Flowering episodes per year||Number||1-2||1|
|Seed production per tree||kg/year||0 – 30||20a|
|Seed oil content||%||31-45||40|
|Seed viability||months||< 12|
|Tree per hectare||Number||320-500||350b|
|Yield estimate (if all trees are productive)||tonnes/ha/yr||7*|
Harvesting the seedsPongamia plantations are not labour intensive. They require one harvest per year and minimal upkeep, especially if interrow cropping or livestock are employed to manage weeds. Mechanical harvesting is the cheapest and most efficient harvesting option. Growers can use either Collossus harvesters or umbrella harvesters, the same as those used in the olive and tree nut industry. Colossus harvesters with associated bins and trailers cost around $900,000. A single Colossus harvester is capable of harvesting a 500 hectare plantation (Section 10.8.4 of Bioenergy in Australia: Status and opportunities [PDF, 9.1 MB], published by Bioenergy Australia in 2012). Table 3. Operating costs of the harvester for 20 kg seed per tree yield scenario.
|Cost item for harvesting||Value|
|Total annual harvest cost (including cost of two drivers)||$202,677|
|Operating cost per hectare per year||$405|
|Operating cost per tree per annual harvest||$1.1|
|Average cost kilogram of seeds in shell||$0.06|
Crushing and transportingOil can be extruded from the seed using the same crushing equipment used in the oil and nut industry. As part of the Bioenergy in Australia: Status and opportunities study [PDF 9.1 MB], researchers estimated the operational costs for operating a seed crushing and oil extrusion plant. A crushing plant with a crushing capacity of 3,345 tonnes of seed in shell each year under the yield scenario of 20 kg of seed per tree is estimated to cost $716,000. This includes:
- building and plant housing
- storage bins for seed and meal
- mechanical press
- oil tanks
- power source for press
- civil works and costs of connection for electricity, water etc.
- seed dehuller and cleaner
- filtration equipment, valves, pumps and plumbing
50 Willowvale Drive, Willow Vale , Queensland 4209
Caboolture, Qld, 4510,
Phone: 0411 619 722
ARC Centre for Excellence for Integrative Legume Research
Queensland University of Technology, Brisbane, Queensland, 4072,
Phone: 07 3365 3550