**3. Obtention of gaseous hydrogen for energy production**

The International Energy Agency (IEA) estimates that world demand for energy should suffer an increase of 45% by 2030 (Birol, 2008). Based on the projections presented, one can expect a worsening of global warming, if no measures are taken that result in significant reduction of CO2 emissions. In addition, we expect a worrying shortage of fossil fuels, if alternative sources of energy are not being widely used.

Among the alternative energy sources, H2 is a very attractive option, as it concentrates high energy per unit mass – 1.0 kg of hydrogen contains approximately the same energy furnished by 2.7 kg of gasoline, which facilitates the portability of energy (Smith & Shantha, 2007). Besides, its combustion generates no contaminants.

Experts have pointed out three major obstacles to the expansion of consumption of hydrogen taking into consideration the technology available at the moment: clean production, low cost, storage and transportation. As a result, most efforts to expand the use of hydrogen as a source of cheap energy has been based on the development of new materials and processes of production.

Among the technologies for hydrogen production, biomass gasification (Albertazzi et al., 2005; Smith & Shantha, 2007), photocatalysis (Ni et al. 2007; Patsoura et al.,2007; Jing et al., 2010), and biological processes (Peixoto, 2008), have been focus of many studies for being routes clean and renewable. The heterogeneous photocatalysis and hydrogen generation by decomposition of water using concentrated solar radiation as primary source energy are between the most promising having gain attention due to their potential.

The great expectation of the global market for the use of hydrogen gas as an important input in the production of energy has been driven by the sectors of energy generation and distribution, which moves large numbers of capital around the world, and is in frank expansion, due to the enormous demand for energy by all sectors (Steinfeld, 2005; Preguer et al., 2009; Pagliaro et al., 2010). Most efforts to expand the use of hydrogen as a renewable energy source has been based on the development of fuel cell technology, both for expansion of its service life, by minimizing costs. Volumes of hydrogen gas have already been produced, both in EU-funded projects, such as the United States.
