Agence France-Presse: Brazilian government chief-of-staff Dilma Roussef opened the five-day event as a last-minute stand in for President Luiz Inacio Lula da Silva. Brazil is keen to see ethanol — the carburant derived from processing organic materials — used more frequently in vehicles around the world. The South American country is the biggest exporter of ethanol, which it makes from sugarcane, and the second-biggest producer, after the United States. The plummeting price of oil in recent …