The introduction of biofuels into the domestic fuel market in Australia has been a vexed issue in the environmental debate. In Europe, the initial call to use biofuels and reduce dependence on fossil fuels was followed a few years later by calls to ban some biofuel sources, such as palm oil, after the environmental consequences of land change and orangutan habitat loss became public knowledge. European nations have led the way by developing sustainability credentials that must accompany biofuel production.

Food versus fuel

Diverting food for use as fuel is another issue. Fortunately, technology is developing at a rate which has seen the biofuels sector reduce its dependence on food crops, such as corn and sugarcane, in favour of biomass from residues and waste. Using crop residues such as wheat stubble and sugarcane bagasse to produce biofuels has removed the food versus fuel argument. However, in terms of sustainability credentials, that is only part of the story.

While the biofuel industry in Australia is small (less than 0.5 per cent of total fuel use) and based largely around co-products from other agricultural markets, the low levels being produced means that environmental sustainability is not currently a pressing issue. Increasing the production of domestic biofuels in the future will, however, increase the amount of feedstock needed to sustain the market, meaning new sustainable feedstocks will need to be sourced.

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Not surprisingly, the question of sustainability principles is arising in Australian conversation about the biofuel industry, particularly around how much secondary generation is available in Australia for biofuel production.

"Sustainability may differ according to the type of feedstock, how much feedstock there is, the technology being used and the region from where the feedstock is sourced," said Dr Deborah O’Connell of CSIRO’s Energy Transformed Flagship at the 2010 Bioenergy Australia conference in Manly, New South Wales.

Separating the wheat from the chaff

The use of residues from the wheat sector provides an example of the complexity of defining sustainability.

Removal of wheat stubble from a field after harvest is the first unknown in terms of how to establish a standardised sustainability credential. Most assumptions include an allowance to remove some stubble and retain some for environmental reasons. However, this allowance may not be sufficient for all types of wheat or all wheat producing areas. Retention of stubble may be necessary to prevent soil erosion and to leave some carbon in the soil. The removal of stubble is not a universal practice either – in some areas of Australia, the norm is to retain all of the stubble as part of zero-till wheat farming.

Dr Alexander Herr from the Sustainable Biomass Production project at CSIRO said “We have assessed stubble production at a fine spatial resolution across Australia. We have then attempted to assess how much of this could be removed for energy, using a series of constraints such as retention for protection from soil erosion.

“However, we have very little empirical data on the impact of stubble removal on carbon levels in the soil, and this is definitely an area which requires further research to provide better assessments.”

Additional sustainability issues arise where the feedstock needs to be transported long distances. Transport increases the greenhouse gas emissions of the feedstock substantially. The use of waste wood diverted from landfill is one such feedstock where this issue is pronounced, particularly in regional areas where numerous residue sources are used to provide the amount of feedstock necessary for a viable industry.

International sustainability credentials

Although no scheme of sustainability credentials has yet been achieved in Australia, there are several being developed overseas, such as the Roundtable of Sustainable Biofuels (RSB) initiated by the École Polytechnique Fédérale de Lausanne. There are numerous other schemes, directives and policies in place overseas which aim to address sustainability issues. However, the RSB scheme is one of the first to recognise that sustainability criteria may reduce the impact of the activities directly associated with the biofuel industry, but that indirect impacts, such as changes in land use or food versus fuel, are the domain of the government itself and not a sustainability criterion.

According to CSIRO’s Dr Andrew Braid, also from the Sustainable Biomass Production project: “Direct impacts are usually divided into environmental, social and economic, however, there are crossovers between these divisions. It is the indirect impacts, like the effect on food security or changes in land use, which are making the headlines. Addressing the direct impacts on the environment and community is just as important.”

An Australian sustainability standard?

Australia does not currently have a sustainability standard, although New South Wales has used the developing RSB standard in its legislation. Developing a national standard will be important for industry and governments.

“A well-founded national standard, which is internationally recognised, will help the industry to demonstrate its sustainability credentials to Australian consumers, as well as to access certain markets such as the European one which legislates a minimum standard,” says Dr Braid.

“In addition, it will help to prevent Australia becoming the dumping ground for fuel or biomass produced in other countries that does not meet those international sustainability standards.”

How much biomass is out there?

Assessment of biomass potential in Australia is complicated by varying definitions not only of how to scientifically assess the theoretical potential of biomass, but also the meaning and calculations for the real potential. The key is to integrate what is physically achievable with the environmental and economic potential, and what is able to be implemented with current policy and infrastructure settings.

Returning to the wheat example, although we can calculate the theoretical potential, being all of the wheat stubble which may grow in Australia in any given year, we then need to assess the other concepts behind real potential. This takes into account things such as the variation of productivity from one year to the next, the harvestable amount of wheat, retention of stubble, achievable transport distances, costs of nutrient replacement to the soil and numerous other factors.

Again, these principles hold true for every other cropping or plantation system in Australia, including sugarcane bagasse and plantation forests, which could potentially provide biomass feedstock for biofuels. The answers to these complex questions cannot be answered on a national scale, but instead paddock-by-paddock, making modeling of the potential biomass a complex and time-consuming task.

Trying to put a number on the amount of technically available biomass across Australia at any given time is a moving target.

Dr O’Connell said “[The] CSIRO uses a whole range of data and models to assess how much biomass is produced, and where. However, only a fraction of this biomass is potentially available to divert to a second generation biofuels industry. We apply a series of constraints, which are like filters, to assess the technical, environmental, policy and economic feasibility of each biomass type.

“Each set of applied constraints reduces the available bucket of biomass. However, it also reduces the variability of the results, increasing confidence and hopefully reducing the uncertainty and risk to a point where investors have confidence to invest in developing a new industry,” she said.

Biofuels and greenhouse gas

“We have identified that we have significant biomass for current production in Australia and that we could produce more in a way sympathetic to current land use,” Dr O’Connell said.

Additionally, in the analysis done by CSIRO based on assumptions made, use of current and new sources of biomass in the next 20 years could potentially scale up the second generation biofuels industry in Australia to “replace more than 30 per cent of current liquid fuel use, [and] use of the biofuel would concurrently reduce greenhouse gas emissions from road transport by more than 30 per cent,” said Dr O’Connell.

An interesting concept produced by the CSIRO research is that greenhouse gas emissions could be reduced by greater than that 30 per cent if the feedstock was used to replace coal for electricity production instead of liquid fuel for road transport. This is because there is less energy lost in the conversion of feedstock to electricity than conversion to liquid fuel, and because the feedstock is replacing coal, which is emissions intensive, rather than a liquid fuel.

However, given the high use of transport in Australia, as well as overseas, our reliance on liquid fuels cannot be discounted. The ability to produce larger quantities of biofuel is limited by feedstock. Therefore, a future biofuel industry may rely heavily on new sources of feedstock and oil producing seeds, the production systems of which have yet to be proven both environmentally and economically in Australia.

Both current and future feedstock assessment of sustainability is dependent on the type of feedstock, how much feedstock there is, the technology being used and the region from where the feedstock is sourced.

At what cost?

Further research being done by the Sustainable Biofuel Production project at CSIRO integrates the technical availability of biomass with economics and demonstrates that using currently available biomass, the production of ethanol from second generation technologies in at least one regional area of Australia could be economically viable and compete in price with petrol.

“Our study shows the break-even price and abundance of biomass for ethanol production in the Green Triangle of South Australia (a 6 million hectare forest region spanning the border area between the states of South Australia and Victoria). However, much of the low cost feedstock is already committed to other markets or serves other purposes,” said Dr Luis Rodriguez, an economist at CSIRO.

The amount of affordable biomass and transport costs are two limiting factors for the size of a potential biofuel plant. Under the current conditions of zero-fuel excise and oil prices (approximately $US80 per barrel), ethanol production is viable using biomass with a plant gate cost (the price of goods charged by manufacturers) of up to $A74 per tonne. However, other factors such as oil prices, exchange rates and government excise might affect the viability of the industry. In the future, the price of fossil fuel is expected to increase as well as the excise rate for biofuels, including ethanol.

The future of biofuels

An interesting finding is that the forecasted increase in oil prices has a higher impact on the price of petrol than the increased ethanol excise on the pump price of the biofuel. Therefore, by 2016, assuming an oil price of $US175 per barrel1 and feedstock with a plant gate cost (the price of goods charged by manufacturers) of up to $A190 per ton might be used for ethanol production, representing a flow of 1.7 million tonnes of biomass per year. Using a simplified greenhouse gas accounting system based on a 2011 study2, this could potentially mitigate up to 1.2 million tonnes of CO2 by replacing fossil fuels with ethanol.

Answering the question of how much feedstock may be available in Australia for biofuels is obviously the short answer to a very long question. Work by the CSIRO continues to assess the technical availability of current and new feedstock systems in Australia which could contribute to a biofuels industry in a sustainable manner.

1 Deutsche Bank, 2009. The Peak Oil Market: Price dynamics at the end of the oil age.

2 Farine, D.R., O'Connell, D.A., Grant, T. and Poole, M.L., 2010. Opportunities for energy efficiency and biofuel production in Australian wheat farming systems. Biofuels, 1(4).