Biobrandstof      (27 januari 2007)

Op 18 december j.l. was er een interessant debat in Wageningen onder de titel: "Toekomst Biodiesel een illusie?"  Voor zij die in deze materie geïnteresseerd zijn: Er staat onder de link wat materiaal dat nuttig is als men zich in dit onderwerp wat nader wil verdiepen.

Toekomst Biodiesel een illusie?

Verder is er een studie door senter/novem verschenen, waarin de mate van duurzaamheid van de bio-ethanol uit rietsuiker wordt bezien.  Daarin komt men tot de conclusie dat er geen doorslaggevende redenen zijn om bio-ethanol uit suikerriet als niet "duurzaam" te beschouwen.

Maar helaas, de materie is weerbarstig blijkens de volgende brief in Nature:

Luiz Antonio Martinelli (a) and Solange Filoso (b)
a. Centro de Energia Nuclear na Agricultura, Avenida Centenàrio 303, 13416-000, Piracicaba, SP, Brazil
b. Department of Entomology, University of Maryland, 4112 Plant Sciences Building, College Park, Maryland, 20742-4415, USA

As Brazilian environmental scientists, we believe that the Business Feature "Drink the best and drive the rest" (1) understates the serious environmental and social problems associated with Brazil's sugar-cane ethanol industry. For instance, although you say that soil erosion is a "potentially" damaging side-effect of sugar-cane cultivation, there is abundant scientific evidence already that environmental degradation from soil erosion in sugar-cane fields is widespread (2). In the state of São Paulo, which is the core of the ethanol industry in Brazil, estimated rates of soil erosion in sugar-cane fields are up to 30 tonnes of soil per hectare per year. Moreover, despite laws to protect the riparian buffers that prevent soil inputs to rivers and streams, only 30% of riparian zones have been preserved in river basins.

The burning of sugar-cane fields before manual harvesting twice a year is another serious environmental problem related to the ethanol industry in Brazil. Although a law passed in 2002 by the state of São Paulo decrees that, by 2006, 30% of the sugar-cane fields with slopes lower than 12% (called mechanizable areas) should not be burned, farmers have been reluctant to replace cheap manual labour with more expensive mechanized harvesting. The deadlines imposed to reduce the burning of sugar-cane fields have been postponed several times, under pressure by sugar-cane farmers. Thus, it is likely that smoke pollution from sugar-cane fields will continue to be a major problem in São Paulo and other Brazilian states for many years, leading to further acidification of the already poor tropical soils (3). Additionally, high particulate concentrations in the atmosphere from sugar-cane burning have been associated with a growing number of human respiratory diseases in sugar-cane regions (4,5).

Last but not least, although the sugar-cane industry generates jobs in Brazil, working conditions, especially for manual harvesters, are extremely poor and often associated with causes of death. Thus — although we agree that Brazil's ethanol industry is "able to get better" — from an environmental and social standpoint, it is far from being as good as you portray.

We believe that the present ethanol industry and proposals for expansion of ethanol production in Brazil and worldwide should be carefully evaluated, to avoid environmental and social problems far outweighing long-term economic gains.

1. Nature 444, 670–672 (2006)
2. Sparovek, G. & Schnug, E. Soil Sci. Soc. Am. J. 65, 1479–1486 (2001)
3. Krusche, A. V. et al. Environ. Pollut. 121, 389–399 (2003)
4. Arbex, M. A. et al. J. Air Waste Manag. Assoc. 50, 1745–1749 (2000)
5. Cançado, J. E. D. et al. Environ. Health Persp. 114, 725–729 (2006)

Één van de achillushielen van bio-brandstof is de mate van duurzaamheid van de gebruikte landbouw methoden.  Ik denk dat daar grote aandacht aan besteed moet worden.  Anders wordt het een doodlopende weg.

Mazzel & broge, Evert

Zie ook: Donkerzwarte brandstof