THE Australian pork industry is kicking goals in the green space, with biogas capture and effluent recycling providing environmental benefits beyond the sty gate.
Pork was the only agricultural industry to be granted contracts under the federal government’s Emissions Reduction Fund (ERF) last month. The industry’s four successful projects recognised in the first ERF auction represent a commitment of 290,000 tonnes of carbon dioxide to be abated.
The piggery projects were focused on the capture of biogas, which is produced by the anaerobic digestion of organic matter in effluent systems. Effluent is collected from pig sheds and conveyed to an anaerobic treatment system (which could be a covered pond or a purpose-built digester) and the biogas can then be used in place of fossil fuel.
Credits generated through the ERF will assist producers significantly reduce payback periods for implementation of these biogas systems.
Over the seven-year life of these contracts the emissions reduction will be the equivalent of getting 11,571 average homes off the grid for one year, said an Australian Pork Limited (APL) spokesperson.
APL chief executive Andrew Spencer said the ERF results highlighted the innovative and progressive nature of Australian pork farmers.
“The industry is walking the talk when taking responsibility for environmental stewardship and reducing its carbon footprint,” he said.
“The pork industry in Australia only accounts for around 0.4 per cent of Australia’s greenhouse gas (GHG) emissions, however mitigation and utilisation of GHGs not only minimises the industry’s environmental footprint but also acts to offset production costs (and) significantly assists in reducing odour issues around intensive animal production systems.
“(It’s) a win-win situation all round,” Mr Spencer said.
APL and the Pork CRC Bioenergy support program have assisted, encouraged and supported producers take up the biogas initiatives.
Piggeries reaping biogas savings
An education and on-farm GHG mitigation piggeries program also yielded results well above expectations.
Over the past two years, producers representing 24 per cent of Australia’s pork production participated in workshops and one-on-one farm consultations as a part of the National PigGas Extension project, delivered by Ian Kruger Consulting. Profitable reductions of up to 84pc of total on-farm emissions have been planned or achieved on individual piggeries.
Baseline GHG emissions were calculated on participants’ farms using the PigGas Calculator, and mitigation strategies were identified.
The average potential to mitigate total on-farm greenhouse gas emissions across all piggeries was 54pc. On a national basis, this is equates to a maximum abatement potential of 588,500 tonnes of carbon dioxide equivalents per year.
Project leader Mr Kruger said this was “a good news story for agriculture”.
“Nearly all pork producers could identify potential emissions savings (and) about half of those in the study have implemented some reduction strategies already, particularly where there was a clear financial return,” he said.
“For example, reducing feed wastage or increasing feeding efficiency by 5pc resulted in about a 10pc reduction in greenhouse gas emissions.
"Modifying existing waste treatment and reuse systems could result in 15-25pc emissions reductions. Housing pigs in deep litter pig sheds resulted in about 40pc lower emissions compared with housing in conventional flushed sheds.”
Mr Kruger said the maximum emissions mitigation was found in conventional piggeries that treated manure in covered anaerobic ponds or tank digesters.
“These digesters capture and burn biogas methane to generate electricity for farm use and sales to the grid," he said.
In these cases, 75-84pc of total on-farm greenhouse gas emissions could be mitigated and the emissions intensities fell from a calculated average of four to below 1 kilogram of carbon dioxide (CO2) equivalents per kilogram of pork produced.
"Over 100,000 tonnes of CO2 have been abated so far from these digester systems installed on over 10pc of pork production.”
Some of the on-farm mitigation options such as reducing feed wastage resulted in direct cost savings, while other mitigation options such as covering ponds generated new farm income streams such as Australian Carbon Credit Units and electricity sales and offsets.
The project is due for completion in May 2015.
Pig waste could provide more for farmers
Meanwhile, Murdoch University researchers have been investigating whether the effluent from piggeries can be effectively treated with micro and macroalgae so that species of the organism can be safely fed back to pigs.
The Co-operative Research Centre for High Integrity Australian Pork (Pork CRC) has invested $300,000 with the Algae Research and Development Centre at Murdoch University to investigate the proposals, which would cut costs, recover energy from waste and reduce the potential for groundwater contamination at piggeries.
Dr Navid Moheimani and his team from the School of Veterinary and Life Sciences have so far discovered three different types of microalgae that can grow on untreated piggery anaerobic digestate effluent, which typically contains extremely high levels of ammonium.
Anaerobic digestion in lagoons or ponds on farms is currently the most common method used to process piggery waste. The discovery is a world first and offers a potentially cost effective means of remediating piggery effluent.
The team has found that microalgae remove ammonia, other nutrients and potentially reduce the pathogen load in the effluent, meaning that the treated waste water can be reused.
The algal biomass produced is potentially a protein rich food source for pigs and other animals, although Dr Moheimani said extensive testing would be required.
“We have high hopes that this method of treating effluent will ensure the algal biomass produced can be fed back to the pigs which will make Australian piggeries much less wasteful and more cost competitive,” Dr Moheimani said.
“Of course if this works for pigs, it could also work for different livestock.
“Pig slurry could well be viewed by the industry as a resource rather than a waste management issue.”
Dr Moheimani and his colleagues are now looking at methods to optimise the growth of the microalgae on the effluent and are bioprospecting for suitable species of macroalgae to grow on piggery effluent. Macroalgae are larger and easier to harvest than microalgae.
The anaerobic digestion process currently used in piggeries produces a low quality fertiliser. A byproduct of this process is the creation of biogas, which is a renewable energy source consisting mostly of methane and carbon dioxide. This is often used to generate electricity on farms.
If they find the micro and macroalgae grown on effluent is unfit for consumption by pigs, Dr Moheimani said his team will investigate how algae can help to maximise biogas production from piggery effluent.
Pork CRC program leader, Rob Wilson, said this was an exciting area of research for the industry and agriculture.
“Australian pork producers are a resourceful group, as demonstrated by the successful uptake of energy replacement by the capture and use of biogas on-farm," Dr Wilson said.
"This work complements the environmental credentials of pork producers while exploring the possibility of producing a food source or a co-digestion product for bioenergy output.”