Renewable and Sustainable Energy Reviews
Biofuels: Environment, technology and food security
Introduction
Today, mankind is facing as once did the mythological Orestes—the harassment of three Furies or Erenias: hunger, the lack of energy and the deterioration of the environment.
The point is that it is mandatory to defeat all these three Furies simultaneously, because any one of them, by itself, is able to wipe out our civilization. Today, for the first time in history, the human race may be the victim of its own genius. Talking about energy, when we think about the whole problem, it is evident to everyone that saving it is the strategic approach to be privileged by reducing the enormous and irrational levels of consumption and increasing the efficiency of the use of conventional fuels, because it gives the best cost/benefit relation; but it is important not to forget the need to find new fuel sources.
Fossil fuels account for over 80.3% of the primary energy consumed in the world, and 57.7% of that amount is used in the transport sector [1]. This way, it is possible to conclude that fossil fuels are responsible for the emission of a significant amount of pollutants in the atmosphere, including greenhouse gases (GHG).
The intensive and low-efficient use of fossil fuels for supplying humans’ energy needs over the past century reduced its reserves considerably, resulting in the prognosis of its exhaustion within the next decades. This phenomenon, known as ‘Peak-Oil’, will probably be characterized by the reduction in the world's oil production that may already start in 2010. This situation is causing a rise in the prices, bellicose conflicts, making some governments considerably concerned towards assuring their energy security. There is a unanimous opinion that says that the era of cheap energy is long gone.
Climatic changes, as a result of global warming caused by greenhouse gases, mainly carbon dioxide (CO2) produced during the burning of fossil fuels, have been causing significant changes in the ecosystems and leading to nearly 150,000 additional deaths every year [2]. The constant rise in Earth's average temperature, threatens millions of people with the growing risk of hunger, floods, water shortage and diseases such as malaria.
Taking the aforementioned problems into account, the use of biomass, particularly biofuels, for energy purposes becomes increasingly interesting.
As a general conception biofuels are products that can be used for powering internal combustion engines. Obtained from natural sources, they are renewable and can recycle the CO2 from their combustion through photosynthetic ways.
They can be direct and immediate replacements for the liquid fuels used in transport and can be easily integrated to the logistic systems that are operating today.
Replacing a percentage of gasoline and diesel, for example, for biofuels (biodiesel or bio-ethanol) is the simplest way to increase the availability of the fuels in the transport sector [3]. The efficient use of the resources involved in the biodiesel and ethanol-producing chain is an indispensable aspect to be studied, which deserves as much attention as the development of alternative fuels.
Given the large extensions of land demanded to grow biofuels crops, the assessment of the impacts that extensive biofuel production programs may cause to food supply and to the environment has considerable importance.
Section snippets
Current panorama of the oil reserves in the world
The world's oil reserves are distributed extremely irregularly. Only some areas have exceptional geological features that allowed the formation and the accumulation of significant amounts of oil. The Middle East concentrates about 65% of the world's reserves, whereas Europe and Eurasia have 11.7%, Africa 9.5%, Central and South America 8.6%, North America 5%, and Asia and the Pacific 3.4% [4] (Fig. 1).
A recent study [5] presents the projection of the world energy demand for the near future (
Conclusions
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From the whole panoramic view for the biofuels production, market and consumers showed above, it is clear that to qualify and to judge biofuels in a generic way conducts to a very notable mistake. The possibilities for use landfarm in each country, the assessment of the food security for the population, the goals for improving air quality in the main cities and the determination of raw materials costs depends (between others factors) of local economies, regional political constraints and mainly
Acknowledgments
The authors want to express their gratitude to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) and Conselho Nacional de Pesquisas (CNPq) for the financial support received.
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