Salman's Infobahn

An anaerobic digestion plant produces two outputs, biogas and digestate; both can be further processed or utilized to produce secondary outputs. Biogas can be used for producing electricity and heat, as a natural gas substitute and also a transportation fuel. A combined heat and power plant system (CHP) not only generates power but also produces heat for in-house requirements to maintain desired temperature level in the digester during cold season. CHP systems cover a range of technologies but indicative energy outputs per m3 of biogas are approximately 1.7 kWh electricity and 2.5kWh heat. The combined production of electricity and heat is highly desirable because it displaces non-renewable energy demand elsewhere and therefore reduces the amount of carbon dioxide released into the atmosphere. In Sweden, compressed biogas is used as a transportation fuel for cars and buses. Biogas can also be upgraded and used in gas supply networks. The use of biogas in solid oxide fuel cells is bei...

The conversion of organic waste material to energy can proceed along three main pathways – thermochemical, biochemical and physicochemical. Thermochemical conversion, characterized by higher temperature and conversion rates, is best suited for lower moisture feedstock and is generally less selective for products. Thermochemical conversion includes incineration, pyrolysis and gasification. The incineration technology is the controlled combustion of waste with the recovery of heat to produce steam which in turn produces power through steam turbines. Pyrolysis and gasification represent refined thermal treatment methods as alternatives to incineration and are characterized by the transformation of the waste into product gas as energy carrier for later combustion in, for example, a boiler or a gas engine. Bio-chemical conversion processes, which include anaerobic digestion and fermentation, are preferred for wastes having high percentage of organic biodegradable (putrescible) matter and hi...

Every energy conversion system wastes a portion of its input energy. For biomass to electricity conversion systems, 50% or more of the energy input can be lost - even up to 90% for some small-scale and alternative technologies. However, the energy rejected from a conversion system can often be used productively for industrial or residential heating purposes in place of burning fuels separately for that purpose. When this is done the overall efficiency can jump to 75-80%. Most systems must reduce their electricity production somewhat to make cogeneration feasible. Thermal applications are the most efficient conversion technology for turning woody biomass into energy and should be considered in the development of a national Renewable Portfolio Standard (RPS). Thermal applications for woody biomass can be up to 90% efficient, compared to 20% for electricity and 50-70% for bio-fuels. Thermal systems can be applied at multiple scales, and are often more economically viable, particularly in...

Ultrasound activated sludge disintegration could positively affect sludge anaerobic digestion. Due to sludge disintegration, organic compounds are transferred from the sludge solids into the aqueous phase resulting in an enhanced biodegradability. Therefore disintegration of sewage sludge is a promising method to enhance anaerobic digestion rates and lead to reduce the volume of sludge digesters. The addition of disintegrated surplus activated sludge and/or foam to the process of sludge anaerobic digestion can lead to markedly better effects of sludge handling at wastewater treatment plants. In the case of disintegrated activated sludge and/or foam addition to the process of anaerobic digestion it is possible to achieve an even twice a higher production of biogas. Here are few examples: STP Bad Bramstedt, Germany (85,000 PE or 4.49 MGD) First fundamental study on pilot scale by Technical University of Hamburg-Harburg, 3 years, 1997 - 1999 • reduction in digestion time from 20 to 4 day...

There are many ways to generate electricity from biomass using thermo-chemical pathway. These include directly-fired or conventional steam approach, co-firing, pyrolysis and gasification. 1. Direct Fired or Conventional Steam Boiler Most of the woody biomass-to-energy plants use direct-fired system or conventional steam boiler, whereby biomass feedstock is directly burned to produce steam leading to generation of electricity. In a direct-fired system, biomass is fed from the bottom of the boiler and air is supplied at the base. Hot combustion gases are passed through a heat exchanger in which water is boiled to create steam. Biomass is dried, sized into smaller pieces and then pelletized or briquetted before firing. Pelletization is a process of reducing the bulk volume of biomass feedstock by mechanical means to improve handling and combustion characteristics of biomass. Wood pellets are normally produced from dry industrial wood waste, as e.g. shavings, sawdust and sander dust. Pelle...

The electricity generation capacity of renewable resources reached an estimated 240 gigawatts worldwide in 2007. Renewable resources represent 5 percent of global power capacity and 3.4 percent of global power generation. Renewable energy supplies 18 percent of the final energy consumption worldwide, counting traditional biomass, large hydropower, and "new" renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels). Traditional biomass, primarily for cooking and heating, represents about 13 percent and is growing slowly or even declining in some regions as biomass is used more efficiently or replaced by more modern energy forms. Large hydropower represents 3 percent and is growing modestly, primarily in developing countries. New renewables represent 2.4 percent and are growing very rapidly in developed countries and in some developing countries. Clearly, each of these three forms of renewable energy is unique in its characteristics and trends. Biomas...