Beyond, the fermentation process also yielded significant amounts of other lower alcohols that were also fed to the chemical industry. This was not feasible during war time and new, extensive cane plantations supplied ethanol that went into the production of acetic acid, ethyl acetate, diethyl ether, ethyl chloride and other derivatives. Later in 1942, a large plantation of sugarcane was established in the Campinas region in São Paulo, by the Rhodia company that previously used to import ethanol from Germany, for its chemicals production in Brazil. Indeed, cars that could not be fueled with the hardly imported gasoline in Brazil used water gas ( gasogênio) as a fuel, a very ineffective solution. However, the production of fuel ethanol was not significant and it remained insufficient to benefit from the opportunity created by the scarcity of oil, during the Second World War. In the 1920s, a fuel factory named Usga operated in the Brazilian northeast, delivering a mixture of ethanol, ethyl ether and castor oil that was used to fuel cars. Mother liquor resulting from sugar crystallization was fermented and distilled to produce beverages like the lower grades of cachaça. Until the 1970s, ethanol was just a sugar byproduct. It was introduced in South and Central Americas by the Portuguese (in the 16 th century), Spanish and French, becoming the major global source of food sucrose. There are many examples of their use in the past and an outstanding case is sugarcane that underwent a large change in its role, during the past four centuries. In Brazil, the amount of agricultural residues is now in excess of 1 billion metric tons every year, whose energy content is roughly equivalent to 200 million metric tons of oil.Īgricultural residues are thus an interesting possibility to increase the use of renewable resources as energy and industrial feedstocks. In some cases, residues largely exceed the amounts of edible material and they are especially significant in large food producers. On the other hand, food production is necessarily accompanied by the production of a huge amount of crop residues. This is demonstrated by the rapid growth of this industry in the Middle East, since the 1980s and even more spectacularly by the upturn of the American industry since shale gas availability increased steeply, for the past 10 years. The viability of the petrochemical industry is critically dependent on the prices and availability of its current inputs, oil or gas. This means that saving oil for the chemical production will necessarily make it much more expensive. This looks logical but we should recall that petroleum extraction, refining and petrochemical production are process industries whose viability is strongly dependent on the production scale. The high value of petrochemical products suggests that oil and other fossil fuels should be saved for chemical production, largely extending the duration of existing reserves. For instance, recent publications describe decision support systems to minimize purchase costs and to maximize profits by production planning, as well as the optimization of the use of resources. Petrochemical industry has been highly successful for many decades and this is due to a number of factors, including the intensive efforts to improve its economics. 40% of the global oil and gas industry revenue. This means that petrochemical industry is based on a small fraction of the overall fossil carbon used, but its annual output is ca. Current production of petrochemicals is based on naphtha (from oil) or natural gas. For this reason, they can only partially replace the current fossil carbon products, especially the fuels that have lower unit value than petrochemicals. However, neither solar- or wind-to-electricity technologies contribute directly to raw materials production. Specific answers to these concerns call for a shift towards renewable resources that can be used without the risk of depletion, and great successes were achieved in recent years thanks to new technologies in solar and wind energy production, to the growing use of biomass for energy and raw materials production and to other promising but less-developed technologies. Growing demands of the ever increasing human population coupled to non-renewable resource depletion led many researchers and policy-makers to issue warnings like those expressed in the well-known book “Limits of Growth”, and its more recent update.
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