Ser ou não ser…verde

Dario Castillejos, «Dario La Crisis»

É um assunto já um pouco esquecido, mas esta semana a The Economist volta ao etanol e aos combustíveis verdes, que talvez não sejam tão verdes. Segundo a The Economist, o etanol do Iowa poderá estar a provocar desflorestação no Brasil:

HOW green is ethanol? The Renewable Fuels Association (RFA), an American lobby for the stuff, obviously wants voters and politicians to think it is very green indeed. The association’s cool-coloured website plays down claims that ethanol may actually harm the environment. The biggest target of those claims these days is that growing maize to make ethanol causes indirect changes in land use by altering the incentives of other, often foreign, farmers.

Adding ethanol to the traditional markets for maize (food and fodder) inevitably pushes the price up. That encourages farmers, including those in poor countries, to boost production. If some of those farmers plough up savannah or cut down forest to grow the extra crops, the carbon dioxide released from the plants destroyed and soil ploughed up reduce the benefits of substituting the ethanol produced for petrol. If forests that are still growing are cleared, the environment loses the effect of their future uptake of carbon dioxide, too.

[…] The American farmer can understandably disclaim responsibility for what a Brazilian logger does. But the RFA’s attitude borders on being in denial. Crop yields almost certainly cannot increase fast enough to make up for the diverted maize, and any tilling of virgin land does release carbon dioxide in large quantities.

[…] A bigger problem, though, is the unstoppable desire of politicians to pick green winners—and not necessarily for green reasons. Ethanol, like “clean coal”, has a habit of being among them not because of its inherent virtues, but rather its political geography. Maize grows in crucial states, some of them “swing” states like Iowa and Ohio. Barack Obama thus recently renewed his support for American, maize-based ethanol. Letting Brazilian ethanol, made from sugarcane, into the market tariff-free would be cheaper and probably greener. But that, of course, is not on. Eventually, new crops such as switchgrass and new technologies that allow whole plants to be converted into ethanol, rather than just their sugar- or starch-rich parts, will change the equation by boosting yields. In the meantime, the truth about ethanol is murky.

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