Ambitious biofuels targets have been agreed in major automobile markets. In the US, a goal of 35 billion gallons of biofuels, replacing approximately one fifth of oil-based transport fuels, is proposed by 2017. Current production is just 4.2 billion gallons. The European Union (EU) Biofuels Directive demands that 5.75 per cent of European fuel comes from biomass by 2010, increasing to 10 per cent by 2020. Even more ambitious targets are being discussed (Doornbosch and Steenblik, 2007).
Bioethanol is the most widely used biofuel for transport and accounts for more than 94 per cent of global biofuel production, the rest being mostly biodiesel from various oil plants such as palm oil, soy and rapeseed (IEA, 2008, p 161). About 60 per cent of the world's bioethanol comes from sugarcane and 40 per cent from other crops. Germany is the market leader in biodiesel where bioethanol is insignificant. With sales at approximately 1.5 million tonnes, biodiesel currently supplies more than 4 per cent of the demand for diesel. The planned increase to 2 million tonnes would allow biodiesel to cover approximately 6 per cent of the current demand. Germany currently has about 750,000ha for biodiesel production; the land available for biodiesel production cannot, however, be extended to more than 1 million hectares. The international trade in biodiesel is only beginning.
Another question is whether plant oils have to be refined into diesel at all. Vehicles can also run on pure plant oil. The energy (and agricultural) balance of pure plant oil from perennial plants such as Jatropha on marginal land is much better, particularly when used for rural electrification in diesel generators.
The biofuel of choice is clearly Brazilian ethanol made from sugarcane, since both in terms of production costs and greenhouse gas balance it tops most other biofuels currently being used. Brazil is by far the largest bioethanol producer and also the largest exporter supplying about half of the global market. However, despite the rhetoric of the Brazilian government about massive exports, Brazil's sugarcane producers themselves put their increased export potential in the near future, at 20 per cent over present levels (Carvalho, 2007).
Brazil produces ethanol first and foremost for its own domestic market. Europe and the US are protecting their own biofuel industries with heavy tariffs and subsidies against cheaper imports. At the same time, Brazilian bioethanol is much more competitive than bioethanol from corn/maize made in the US, for instance, and its energy and greenhouse gas balance is also much better. The question, then, is why protect economically and environmentally inefficient American or European producers from international competition?
Neither bioethanol nor biodiesel are the best option to reduce emissions and oil dependence in the transport sector. It is impossible to supply a major share of today's global market of liquid transport fuels based on bioethanol and biodiesel. Not only is the production of these fuels too inefficient, but so is the transport system itself. There is no way to get out of petroleum's grip without addressing the way in which mobility is organized today. It should be pointed out that the EU biofuels target of 10 per cent by 2020 can be achieved by reducing the consumption of fossil fuels in the transport sector and, thus, automatically increasing the share of biofuels without actually increasing their absolute amount.
This requires a modal shift in the transport sector. The automobile-centred transportation system dominant today is energy inefficient and cannot be extended to the whole world. It is not possible to produce the enormous amount of fuel needed for this transport system in a sustainable manner. The removal of the many counterproductive subsidies for aviation and road transport is a prerequisite for a reduction of absolute transport demand by discouraging excessively dispersed production cycles and settlement patterns. Modern and attractive public transport systems, including massive expansion of railways, for both passenger and freight transport, are the cornerstones of a sustainable transport system of the future.
Taking all that into account, there will still be a need for biofuels for motorized vehicles. Strict fuel-efficiency criteria and policies to take gas guzzlers off the market, increasingly implemented in places such as California and China, will be inevitable. This will have much more impact for reducing the petroleum consumption of the transport sector than any shift to alternative fuels. To put it bluntly: 1000 people using public transport powered by conventional electricity are emitting much less greenhouses gases than 1000 people driving biofuel-powered sports utility vehicles (SUVs).
Biogas: The biofuel of choice
For alternative fuels, we need to look beyond ethanol or biodiesel. More and more studies show that biogas is more efficient than bioethanol produced from sugarcane (Brazil) and even more efficient than bioethanol from maize or sugar beets. Biogas (biomethane) is even more impressive as a fuel when net energy yields per hectare are compared. The gross biofuel yield from 1ha of agricultural land is 4977 litres of fuel equivalent for biogas, 4179 litres for ethanol from Brazilian sugarcane, 4054 litres for ethanol from sugar beet, 3907 litres for biomass to liquid (BTL, so-called second-generation liquid biofuels), a lousy 1660 litres for bioethanol from corn, and 1408 litres for biodiesel from rapeseed.
The picture is even more pronounced when you look at the net energy balance - when you take into account the amount of energy necessary to obtain the energy stored in bioenergy. Today, biogas from silage maize, Sudan grass and other productive energy plants already produces a net energy yield of 42,000 to 62,000 kilowatt hours (kWh) per hectare. In contrast, BTL can only produce around 33,600kWh. The energy-intensive process of distilling bioethanol from whatever source generally produces an even less impressive net energy yield, depending upon the kind of energy input. In terms of carbon dioxide saving costs, biogas is the most favourable of all biofuels. In addition, second-generation biofuels are produced by transforming biomass in a high temperature (energy-intensive) chemical industrial process into liquid fuels. This does not allow for the recycling of plant materials as fertilizers, thus requiring chemical fertilizers with a corresponding additional energy input. The residues from second-generation biofuels are essentially industrial waste. In contrast, biogas production takes carbon out of the agricultural cycle and the residues with all the nutrients can be recycled to the agricultural system. In principle, biogas production is compatible with organic agriculture. Compared to bioethanol and biodiesel as well as to the second-generation liquid biofuels, biogas is more efficient. The biofuel of choice should therefore be biomethane/ biogas, and the biofuels quota should be primarily met with biogas.
Biogas for transport is a technology already available worldwide since biomethane is physically identical with natural gas. Today there are more than 6 million natural gas/compressed natural gas (CNG) vehicles already operating globally. Biogas production is also an interesting component for sanitation systems. Coupling sanitation systems with biogas production can provide the necessary water for biogas production (important in arid regions) and make an important attractive link between energy and sanitation.
More attention has recently been placed on electric vehicles. Depending upon the way in which the electricity to run them is produced; they may well be in the longer run the most promising option for motorized vehicles. However, in a future electricity mix a considerable part will be produced from biomass, so even for electric vehicles there will be a substantial bioenergy component. A shift to both biogas and electric vehicles will have enormous economic and political consequences because such a shift will take the powerful oil companies completely out of fuel production and perhaps even out of fuel distribution. It is also not the optimal choice of most automobile companies who have all invested in other options. The biogas option would mean a dramatically increased role of farmers and natural gas companies, at the expense of the oil companies. The shift to electric vehicles would leave no role for oil companies at all. Don't be surprised if there is a substantial resistance from this sector against these options.
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