Is there really no trouble in a biofuelled sky?

Renewable Transport Fuels

Biomethane
In the previous post I discussed the renewable transport fuel bio-methane, produced through the purification of biogas after anaerobic digestion. In addition to bio-methane, other transport fuels include biodiesel and biomethanol.

Bio-methanol
Biomethanol is produced using plants such as wheat, sugar beet, maize and sugar cane through the process of fermentation, distillation and dehydration. The largest produced of biomethane is currently Brazil where almost half of the fuel used for transport is biomethane fuel. New EU regulations permit blends of up to 10% with biomethanol and 5% blends with petrol are permitted - engine modification may be required however.

Bio-diesel
Biodiesel is produced through the process of transesterification. Through the separation of glycerine from vegetable oil biodiesel is produced. The glycerine can be used in other products such as soap while biodiesel can be used as a straight fuel - alternatively it can be blended with mineral diesel to create a diesel blend - engine modification is not required for either type.

The transportation and energy sectors are major anthropogenic sources of greenhouse gas emissions (GHG). Agriculture is also a large source, representing about 9% of total GHG  emissions, the most important being nitrous oxide and methane (Mata et al, 2010). With future growth inevitable, the global consumption of energy thus poses a serious threat in terms of environmental change - affecting the atmosphere and thus global warming but also the oceans too.

Finding clean and renewable energy sources is thus one of the most important but also the most challenging problems facing mankind. Biofuels offer new oppotunities to diversify income and fuel supply sources, they promote employment in rural areas, offer of long term replacement of fossil fuels, reduce GHG emissions, boost the decarbonisation of transportation fuels and increase the security of energy supplies (Mata et al., 2010). In this regard, they undoubtedly offer promise for the future and sequentially the production of biofuels has increased.

The global production of biofuels is estimated to be over 35 billion litres and this figure is expected to grow due to policy measures and biofuel production targets (COM, 2003). In the EU the main alternative to diesel is biofuel and as a result it represents 82% of the total production of biofuels. In Brazil and the United States political and economic objectives are encouraging a growth in biofuel production.

Unfortunately, however, a number of potential limitations of renewable transport fuels have been highlighted by academics and as a result the potential of biofuels is hindered.

Firstly, the price of biofuels in comparison to diesel has been highlighted as a key set backs. Biodiesel, for example, is produced from vegetable oils and animal fats and as the former can also be used for human consumption the production of biodiesel poses a major threat in terms of increasing the price of food-grade oils and biodiesel. In such a case, despite its advantages, the cost of biodiesel would prevent its usage. Thus in order for biodiesel to become an alternative, it must compete economically with other fuels and not compete with edible vegetable oils. Economically, biodiesel prices depend heavily upon the cost of feedstocks used to produce the fuel as these account for 65-70% of the total price (Canakci and Sanil, 2008). Thus to be low cost and profitable the feedstocks must have low costs. In addition to this, the must be produced from non-edible oils, animal fats, soap stocks and greases to not affect the price of edible oils. Additionally, biodiesel and thus biofuels need to have lower environmental impacts whilst ensuring the same level of performance of existing fuels (Reinhardt et al., 2008).

Before the latter is even assessed, the feasibility of biofuel production presents a hurdle that would be difficult to overcome in that the quantities of waste oils and animal fats available today are not enough to meet the demands for biodiesel, nor are there enough feedstocks for the production of biomethane and bioethanol to meet demands.

In addition to this, the total land required for biofuel production exceeds the amount of available arable land for bio-energy crops. In order to meet demands more land for bio-fuel production would therefore be needed (Scarlet et al., 2008). This poses a possible threat as pressures for land use change and increases of cultivated land will lead to land competition and biodiversity loss through deforestation and the use of ecologically important areas (RFA, 2008). Moreover, biofuel production presents a threat to food security when it involves replacing crops used for human consumption.

The sustainability of renewable transport fuels are thus complicated by issues of feasibility in the face of current energy demands. On balance, they present the opportunity to diversify sources of energy and in doing so the threats towards energy security are relieved, however, in terms of being an option to be adopted in the future to address climate change, renewable transport fuels simply do not have the capacity to fully meet demands and thus replace the use of fossil fuels. Increasing the capacity of biofuels to meet demands entails social and economic issues such as price increases and food security.