Biohidrogeno

E C O LO GIC AL C H E M IS T R Y AN D E N GIN E E R IN G S Vol. 16, No. 3 2009

Adam SMOLIŃSKI*1 and Natalia HOWANIEC*

SUSTAINABLE PRODUCTION OF CLEAN ENERGY CARRIER - HYDROGEN
ZRÓWNOWAśONA PRODUKCJA CZYSTEGO NOŚNIKA ENERGII - WODORU

Abstract: The state-of-the-art in biological hydrogen production methods is presented with a special focus on the process of the anaerobic fermentation oforganic wastes. The recently reported levels of hydrogen yields in laboratory scale bioreactors and main challenges on the way to commercial implementations of biological, fermentative hydrogen production systems are given. Keywords: hydrogen, biological production, anaerobic fermentation, organic waste

Introduction
Nowadays, over 80% of the global energy production is based on fossil fuelscombustion processes, inherently combined with emission of contaminants, such as COx, NOx, SOx, CxHy, carbon black, ash, tars and organic compounds. Depletion of global fossil fuels resources as well as an increasing environmental awareness made the research society search new, environmentally friendly, economically attractive and commonly accessible energy carrier. According to analysts hydrogen islikely to become such an ideal energy carrier in the medium-term perspective. Hydrogen is the most abundant element in the universe, the lightest one (0.09 g per dm3) and of a considerably heat of combustion (10 MJ/m3) [1]. Furthermore, water is the only hydrogen combustion product, which makes it an extremely attractive fuel in terms of environmental protection. Hydrogen may be stored in gaseous,liquid or solid (metal hydrides) form and transported by pipelines, with losses smaller than in case of electricity transport. Up to date hydrogen is widely used in hydrogenation processes, chemical removal of oxygen traces (corrosion prevention), as a rocket engine fuel and as a cooling medium in electric generators systems [2, 3]. Hydrogen production is based mainly on fossil fuels, biomass andwater. Natural gas comprises over 90% of the first group of hydrogen production
*

Department of Energy Saving and Air Protection, Central Mining Institute, pl. Gwarków 1, 40-166 Katowice 1 Corresponding Author: email: smolin@gig.katowice.pl, tel. 032 259 22 52, fax 032 259 65 33

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Adam Smoliński and Natalia Howaniec

base. Steam reforming of methane is conducted catalytically atthe temperature of 1100°C and results in generation of hydrogen and carbon dioxide. These gases are also the main products of coal gasification. At present, the technologies of coal gasification combined with separation of hydrogen and sequestration-ready carbon dioxide constitutes the subject of extensive research works worldwide. However, energy demanding and emission generating thermochemical andelectrochemical hydrogen production processes can hardly be considered sustainable. An alternative solution may lie in an application of biological methods, which means employing natural microorganisms, which produce hydrogen as one of their metabolic products. These processes in majority are conducted at ambient temperature and pressure, which implies lower system energy demand. They also createnew possibilities for renewable energy resources utilization. The most promising in these terms seems to be an anaerobic fermentation process, combining renewable-based clean energy carrier production with organic waste utilization in environmentally friendly way.

Biological methods of hydrogen production
Biological hydrogen production has been scientifically recognized for over a centurynow. Basic research on microbiological hydrogen production processes were undertaken in the twenties and applied in the seventies of the 20th century. Although these were mainly focused on photosynthesis systems, among the microbiological methods of hydrogen production besides water biophotolysis (microalgae) and photofermentation (photosynthesizing bacteria) one can also distinguish a very...