The current edition of Science focuses on energy and sustainability with a terrific online collection of notes, comments, and essays. Some notes from an article in this week’s edition of Science. The article is titled “Ethanol for a Sustainable Energy Future” by Jose Goldemberg. Some notes:
…exhaustible fossil fuels represent ~80% of the total world energy supply. At constant production and consumption, the presently known reserves of oil will last around 41 years, natural gas 64 years, and coal 155 years (2). Although very simplified, such an analysis illustrates why fossil fuels cannot be considered as the world’s main source of energy for more than one or two generations.
Today, ethanol production from sugarcane in [Brazil] is 16 billion liters (4.2 billion gallons) per year, requiring around 3 million hectares of land. The competition for land use between food and fuel has not been substantial: Sugarcane covers 10% of total cultivated land and 1% of total land available for agriculture in the country. Total sugarcane crop area (for sugar and ethanol) is 5.6 million hectares.
Subsidies for ethanol production are a thing of the past in Brazil (Fig. 2), because new ethanol plants benefit from the economies of scale and the modern technology available today, such as the use of high-pressure boilers that allow cogeneration of electricity, with surpluses sold to the electric power grid.
There's a large debate on biofuel (ethanol or biodiesel). for example, we should consider that the consumption of oil for the US is 3.2 billions of oil *a day* (10 times the consumption of Brazil) ! With the current production of ethonal of Brazil, the US economy could not even last a week… Brazil has the vast and very productive land compared to the rest of the world. If a country like the United state wanted to fulfill their needs with biofuels, the cultivable lands would not be enough. (Plus : to increase their cultivable lands, brazilians authorites accept to cut rain forest, as they do in Indonesia… is it what we want ?).
In Mexico for example, there's competition between food and energetic use of land. It gave birth to what is known as the tortilla crisis (http://www.washingtonpost.com/wp-dyn/content/article/2007/01/26/AR2007012601896_pf.html) : the current explanation of this crisis is that the US buy corn to produce bioehtnaol and rised the price of corn. Consequently, the price of tortilla, the basic element of nutrition in Mexico for poor families has doubled. Brazilian are lucky if there not such a concurrence, but other countries may face bigger problem.
Add to this that increasing the production of corn, sugarcane or anything else has an impact on the environment. Given the actual knowledge, it seems that adding a low percentage of biofuel in gasoline (up to 20%, maybe less) is realistic without large environmental and economic impact. If countries like the U.S or Canada try to go further, the solution might have perverse effects.