In spite of increased utilization of energy-saving technologies, the global energy consumption will rise dramatically in the next few years. Particularly, rapid industrialization of developing and threshold countries, as well as increasing global human population contribute to excess energy consumption. Fossil fuels, currently constituting the main energy sources, will reach a conveyance maximum level. After transcending this level, the post-fossil age is beginning.
This scenario causes, that special formulations of political intentions have to be made, which ensure not only future energy supplies, but also reduce greenhouse-gas emissions. Those intentions can be achieved by reducing energy consumption, increased utilization of renewable energy sources as well as by use of hydrogen and fuel cells. The European Union agreed to the obligatory rate of 20 % of renewable energy source supply until 2020. Hydrogen as alternative energy source should account for 5 % (Schindler et al., 2008).
Hydrogen is the smallest chemical element with the lowest density. Hydrogen is the most abundant element in the universe, as 90 % of all atoms are hydrogen. Despite of the simple constitution, including only one proton and one electron (most common form), hydrogen possesses an high mass-specific energy content (figure 1). The basic calorific value is with 33,33 kWh/kg higher than that of fossil energy sources. The energy content of 1 kg hydrogen corresponds with 2.75 kg petrol (Jungmeier, 2006).
Figure 1: Chemical demonstration of the smallest and simplest element: Hydrogen. It has an electron configuration of 1s1 in its ground state.
Hydrogen is like electricity an universal, secondary energy source. It can be produced of a variety of primary energy sources. Electrical energy can only be storaged limited, however, by liquefaction and condensation hydrogen can be storaged easily with only low storage and transport deficit.
Hydrogen can be produced in different processes, which use either fossil or renewable energy sources. The fermentative hydrogen production of biomass certainly is less energy intensive and therefore environmentally more compatible, compared to the thermo-chemical gasification process. Additionally, the potential of biomass is ensured in most countries, also being advantageous for developing countries. Hydrogen production of biomass could also facilitate integration of Eastern European countries, because of the excessive supply of agro-area.
However, Hydrogen is environmentally much more compatible and enduring than fossil fuels. By use of hydrogen in transport and stationary sector, no contaminants are emitted, as only water is released during conversion.
Utilization of hydrogen can effectively reduce the dependency of fossil energy imports, including crude oil and petroleum gas, resulting in political independency and further economical development in Europe.
The EU-project "Hyvolution" is an integrated project in the course of the 6. European General program about sustainable energy-systems. The full title of this project is: "Not-thermic absolute hydrogen production of biomass". The aim of this project is the schematic development of an industrial bioprocess for the local production of hydrogen. This process should be applicable in small-scale plants, using locally produced biomass. Therefore, 10-25 % of the hydrogen demand of the EU for electricity production and/or for fuel usage should be covered. The project should be done in an alternative form, which is divided into two processes:
Firstly, hydrogen, carbon dioxide and intermediate products are produced during thermophilic dark fermentation.
The indermediate products constitute organic acids (e.g. acetate and lactate), which are then – in the second process step, called photoheterotrophic fermentation, decomposed into hydrogen and carbon dioxide. Due to this multi-stage process, a 75 %-biomass conversion rate to hydrogen should be achieved.
22 partners from the research and industry sector (13 countries, mostly EU-countries) contribute to this project. In figure 2, an outline of several project parts, including all aspects of hydrogen production of biomass, is shown.
- Workpackage 1 includes allocation of technologies for pre-treatment and logistic of energy-plants and biogenic waste materials in order to facilitate optimal biodegradation.
- Workpackage 2 and 3 contain optimization of particular fermentation processes, including rate of yield and productivity. Additionally, the development of appropriate reactor systems, as well as improvement of process parameters and fermentation processes are part of workpackage 2 and 3.
- Workpackage 4 includes optimization of gas purification and further processing, important for being used in fuel cells.
- Workpackage 5 covers energy-demand minimization and product yield maximization by system-integration for creating an optimal overall process.
- Workpackage 6 includes social integration. Therefore, public consciousness and acceptance for hydrogen and hydrogen production of renewable feedstocks should be increased.
Figure 2: Organization of "Hyvolution project" (source: Claassen et al., 2006)