A Global Village
Issue 4 » Energy & Environment

Biofuels: Not just ‘Food vs Fuel’, but ‘Drink vs Drive’ too

Andrew Purcell, Imperial College London

During the past few years, biofuels have gained much attention as a potential source of renewable energy in the pursuit of climate change mitigation and reduction of GHG emissions. In 2008, biofuels provided 1.8% of the world’s transport fuel in anticipation of continuing growth. Yet, the rapid increase in agricultural and food prices leading to the 2008 global food crisis, partially fuelled by the use of grains and oilseeds for the production of ethanol and biodiesel, has raised concerns regarding the ethical implications of diverting agricultural land and crops to energy production. There are further concerns that a vast increase in agricultural cultivation could have environmental implications that would paradoxically have a negative impact on any attempt to reduce GHG emissions.

So is the reality of this ‘green’ technology that it is simply fraught with too many drawbacks – both social and environmental – to make it a desirable future energy solution? 

With the current wave of protests sweeping the oil-rich regions of North Africa and the Middle East, Brent crude oil prices have risen to well over $100 per barrel. This has led to increasing speculation that biofuels and other currently expensive renewable energy sources may be back on the agenda. Biofuels have become very attractive in the past few years due to the relative abundance of feedstocks, their easy utilisation in combustion engines for transportation and also due to compatibility with the existing fuel distribution infrastructure providing a new end market for agricultural commodities. Biofuels are believed to have the potential to substantially decrease GHG emissions, however, several factors may limit this effort. Any calculation of a reduction in GHG emissions due to biofuel production must take into account not only the alternative fossil fuel consumption but also input fossil fuel consumed during biomass cultivation and any GHG released due to clearing of land with high carbon storage value. Depending on the biofuel type and production pathway, biofuels can have estimated net GHG savings of up to 80% compared to fossil fuels. Indeed, the total CO2 emissions from 10% of the global diesel and gasoline consumption during 2030 were estimated at 0.84 Gt CO2, of which biofuels could substitute 0.17 to 0.76 Gt CO2 (20-90%). However, the annual CO2 emissions from direct land conversion alone are estimated to be in the range of 0.75 to 1.83 Gt CO21 thus having a substantial impact on any perceived CO2 reduction. 

Food Crops vs. Fuel Crops
The land needed to grow energy crops competes with land used for food and wood production. In the case of bioethanol, there is direct competition between food and fuel, as the corn from which the ethanol is obtained is also a staple food for much of the world’s population. We saw in 2008 that the price of oilseeds went up 94% compared with 2007 and wheat prices increased by 126% in the period January-April 2008, as compared to the same period in 20071 leading to a global food crisis. 

The larger the area dedicated to
biofuel crops, the less land that
remains for growing food crops

Biofuels can still drive up food prices even when the plants in question aren’t those usually consumed by either humans or cattle. As biofuels in general face higher costs compared to fossil fuels, governments have largely supported biofuel development with mechanisms such as subsidies, tariffs and tax exemptions. These incentives and benefits were the main driver of development of energy farming and the biofuel industry. However, there’s a risk that too many farmers choose to produce biofuels rather than food. Quite simply: the larger the area dedicated to biofuel crops, the less land that remains for growing food crops. The global land use for the production of fuel crops covered about 2% (36 Mha) of the global cropland in 20081. Even with more land cleared for farming, there is a limit to the amount of land that can sustainably and profitably be cultivated. With the global population expected to reach 9 billion by 2050, there is already great pressure on available agricultural land to produce enough food to sustain our rapidly growing numbers.

The End of Biodiversity
Clearing of land for biofuel crops can be a major driver for deforestation causing environmental degradation and loss of biodiversity. Furthermore, crop plantations tend to absorb significantly less carbon dioxide than forests. In fact, destroying forests to make way for biofuels leads to a destabilization of the ecosystem and, due to decreased productivity, may lead to an increase in the net release of carbon dioxide. One particular case for concern is the increase in palm oil cultivation in South East Asia leading to a clearing of the rainforest there. About two thirds of the current expansion of palm oil plantations results from deforestation while only one third is based on existing agricultural land. Moreover, a quarter of these converted areas contained peat soil with a high carbon content thus releasing CO2 when drained for oil palms. By 2030, the total rainforest area of Indonesia is projected to have decreased by 29% in comparison to 2005 levels1.

About 118 to 508 Mha would be required to provide 10% of the global transport fuel demand with first generation biofuels in 2030 – it is estimated that this would equal 8% to 36% of current cropland, including permanent cultures. Increased biofuel production is therefore expected to have a significant impact on biological diversity in the coming decades, mostly as a result of habitat loss, increased invasive species and nutrient pollution. Studies of the ‘Insurance Hypothesis’, or the effect of environmental fluctuations on ecosystems and biodiversity, have shown that diverse plant ecosystems will tend to photosynthesise at a greater rate than ecosystems with fewer species present. 

Destroying forests to make way for
biofuels leads to a destabilization of the
ecosystem and, due to decreased
productivity, may lead to an increase
in the net release of carbon dioxide

The idea behind the ‘Insurance Hypothesis’ is simple: when different species are present, they are able to fulfil a variety of different ecological niches within a given ecosystem. By contrast, with monocultures, all of the individual plants are competing for the same resources held within one specific ecological niche. Consequently, the overall rate of photosynthesis in biodiverse ecosystems tends to be much higher than that of monocultures, which means biodiverse ecosystems, usually natural ones, are much better at helping us tackle climate change.

In addition, monocultures are much more susceptible to disease than biodiverse ecosystems; plant viruses are usually specific in attacking a particular species, genus, or family of plants. Consequently, it is possible for one viral strain to destroy an entire monoculture plantation of biofuel crops, thus reducing the photosynthesis rate of this area of land to zero. In stark contrast to this, should a virus destroy any given type of plant within a biodiverse ecosystem, the gap created will quickly be filled by the other plant species present. Thus, the clearance of forests, in order to make way for biofuel crop plantations, is not only detrimental in terms of the animal species lost, for whom this forest was their habitat, but it can also cause a net increase in atmospheric carbon dioxide levels over time. 

Further ecological concerns include excessive use of pesticides as well as overexploitation of water resources. Whilst nitrogen fertiliser is in relatively abundant supply, its increased usage will inevitably lead to an intensification of problems such as eutrophication and soil acidification and degradation. Furthermore, of particular concern is the increased water usage which widespread biofuel production may entail. Agricultural activities already use around 70% of the global freshwater supply and, with the proportion of the world’s population living in water-stressed areas set to rise to two thirds by 2025, this is of significant concern. Furthermore, many of the processes involved in farming biofuel crops produce a substantial amount of carbon dioxide. This is not only in terms of the carbon dioxide produced by farming machinery, but also the carbon dioxide emitted through the process of distributing the biofuels produced throughout the world, both overseas and overland. 

Is Algae the Answer?
However, there are developments on the horizon that could make biofuels a much more appealing proposition. One solution would be to use degraded, marginal, or abandoned land for biofuel production. In addition, certain crops, such as switchgrass, may even restore productivity of degraded land. There are woody and herbaceous non-food crops, such as Miscanthus, which have low maintenance costs and can easily be combusted to produce relatively large amounts of energy. Whilst these crops do not directly drive up food prices, as they are not usually crops we would consider edible; they still suffer from many of the issues detailed in this article. More promising, perhaps, is the prospect of using biofuels produced from algae, which experiments have shown can produce up to fifty times more energy per hectare than some land crops4. In addition, significant levels of funding are currently being directed towards researching organisms that may be genetically modified to secrete hydrocarbons. Furthermore, developments in cellulosic ethanol production techniques have recently been a cause for measured optimism. These second and third generation biofuels require significantly less water per gallon of fuel produced and tend to avoid the more severe land-usage problems associated with traditional biofuels.

Ecological concerns include
excessive use of pesticides
as well as overexploitation
of water resources

Thus, whilst biofuels may contribute to the future energy mix, there are many concerns regarding their social, environmental and ecological cost. Hence, as rising oil prices ignite the debate on biofuels once again, we must think carefully before commiting ourselves to further investment in this technology. Perhaps economic measures may be put in place to help us reduce the effect of biofuel crops on world food prices, but the environmental issues are somewhat more difficult to tackle. Of particular concern is land usage, and associated costs due to a decrease in biodiversity. Indeed, calculating and modelling future biodiversity for the next couple of decades has shown that GHG reductions from biofuel production would often not be enough to compensate for the biodiversity losses from increased land use conversion1.

So, perhaps it is time to finally abandon the idea of using hydrocarbons as fuels, whether these are obtained from oil, gas, or biological sources. Instead, ought we not start turning our attention to developing transport infrastructure powered solely by electrical means? If so, the next question to be answered is: what are the relative roles for renewable sources such as wind and solar power in generating this electricity? And what role, if any, will nuclear energy play?

Andrew Purcell is a postgraduate MSc Science Communication student and editor of I, Science magazine.

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[1] United Nations Environment Programme, UNEP (2009). Assessing Biofuels.
[2] Naeem, S. & Li, S. (1997). Biodiversity enhances ecosystem reliability. Nature.
[3] Yachi, S. & Loreau, M. (1999). Biodiversity and ecosystem productivity in a fluctuating environment: The insurance hypothesis. Proceedings of the National Academy of Sciences of the United States of America.
[4] US Department of Energy. Production of Biofuels from Biomass http://www.science.energy.gov/sbir/solicitations/FY%202009/18.EE.Biomass.htm