Venko Beschkov

By Venko Beschkov

Nowadays the world economy is based mainly on petrol as an energy source and raw material for chemical products. The global economic growth in the past century has led to high energy consumption, mainly from fossil fuels, such as coal, oil, and natural gas. The extensive use of fossil fuels formed and stored underground for millions of years has made impossible for the present vegetation on Earth to treat the emitted carbon dioxide by photosynthesis, leading to strong emissions of carbon dioxide and greenhouse effect with the consequent climate changes. One of the ways to cope with this global problem is to close the carbon cycle in nature by the use of renewable biofuels enabling recycling the sources of biological origin by energy production and consumption of the resulting carbon by photosynthesis. Some of these biofuels are biogas (a mixture of methane and carbon dioxide) generated from organic waste; ethanol, produced by fermentation of carbohydrates; and biodiesel, produced by transesterification of lipids. Another feature of this approach is the utilization of organic waste as energy, thus leading to multiple benefits for the environment: waste treatment with energy production, closing the natural carbon cycle, and saving of fossil fuels. Biofuels with their feedstock also serve as raw materials for new technologies for chemicals being now produced from petrol, natural gas, and coal.

Part of the book: Frontiers in Bioenergy and Biofuels

By Sonia Damyanova and Venko Beschkov

The global economic development in the twentieth century has led to extensive use of fossils, such as oil, natural gas, and coal as fuels and chemical feedstocks. This extensive use of fossil fuels has led to enormous emissions of carbon dioxide as final product of combustion. The high absorption rate of infra-red rays by carbon dioxide has led to the so-called “greenhouse” effect. Nowadays, the renewable energy sources based on biomass have become very important with a trend to replace oil consumption at least partially and hence to remediate the emissions of greenhouse gases in atmosphere. Biofuels could be used as alternative raw material for chemical production. One of these biofuels is biogas released at anaerobic digestion of different natural organic waste. Another feature of biogas applications is its utilization as feedstock for the production of synthetic fuels and chemicals being now produced from oil and coal. A new approach is to use biogas as a fuel in fuel cells as a very promising option for energy production from renewable sources. The present review summarizes the applications of biogas for chemicals, starting with dry reforming and Fischer-Tropsch syntheses and as a source of energy, as heat and electricity production by co-generation and fuel cells.

Part of the book: Biorefinery Concepts, Energy and Products

By Venko Beschkov and Elena Razkazova-Velkova

Industrial fermentation and biological wastewater treatment are usually based on redox processes taking place in living cells and on enzyme processes. The practical application of these redox processes is usually associated with electricity generation in microbial fuel cells or process enhancement in microbial electrolysis cells. The microbial fuel cell approach leads to straightforward wastewater treatment with less energy demand. Additional advantages of these processes are the direct removal of various pollutants and the avoidance of addition of chemical agents with the resulting waste products of treatment as it is familiar with the traditional chemical methods. Another option for the use of bioelectrochemical processes in practice is the approach of microbial electrolysis cells. The application of electric field on fermentation or microbial wastewater treatment processes might result in different aspects: either in purely electrochemical processes on the electrodes or in different types of bioelectrochemical stimulation of enzyme activity in the living cells. These applications are associated with the combination of enzyme activity with electrochemical processes to produce or remove certain compounds rapidly at high concentrations with no additions of other chemicals. In the present chapter, both approaches (microbial fuel cells and microbial electrolysis cells) are presented and discussed. Some practical applications and experimental examples of such bioelectrochemical redox processes stimulated by constant electric field are demonstrated.

Part of the book: Energy Storage Battery Systems

By Venko Beschkov

Biogas is an excellent example of renewable feedstock for energy production enabling closure of the carbon cycle by photosynthesis of the existing vegetation, without charging the atmosphere with excessive carbon dioxide. The present review contains traditional as well as new methods for the preparation of raw materials for biogas production. These methods are compared by the biogas yield and biogas content with the possible applications. Various fields of biogas utilization are discussed. They are listed from simple heating, electricity production by co-generation, fuel cell applications to catalytic conversions for light fuel production by the Fischer-Tropsch process. The aspects of carbon dioxide recycling reaching methane production are considered too.

Part of the book: Biogas