How to convert waste material into Energy!! Waste to Energy Conversion Technology!!

Waste to Energy Conversion Technology

Wastes can be converted to fuel by means of numerous processes. The actual selection of a method can rely upon the kind and amount of available waste feedstock, the desired energy carrier(s) (end-use), environmental standards, economic conditions, and other factors. For example, wastes can be directly burned as fuel. However, this fashion of use is thought to be a supply of terribly substantial pollution. Therefore, it is necessary to convert waste into liquid or gaseous fuels which can replace oil. A large variety of liquid and gaseous fuels can be derived from wastes.

There are several methods available to convert wastes into a useable form of energy. The foremost among them is thermal conversion where combustion, gasification, and pyrolysis are used to retrieve energy from the biomass. The next is biochemical conversion where microorganisms during fermentation, anaerobic digestion and esterification release energy from the wastes. Biochemical conversion is usually preferred for wastes with high water content.

1. Thermal Conversion of Waste to Energy

Thermal conversion processes are divided into 3 totally different categories; combustion, gasification, and pyrolysis with each the process being dependent on the concentration of oxygen. Combustion takes place in an environment with an excess of oxygen, gasification is a partial oxidation process requiring an oxygen concentration slightly below the stoichiometric level. Pyrolysis occurs in the absence of oxygen.

    1.a. Direct Combustion Technology

Biomass is burned directly in waste-to-energy plants with none chemicals process to supply steam for creating electricity. Direct combustion and co-firing with coal for electricity production from biomass has been found to be a promising methodology within the nearest future. Also, biomass is burned to produce heat for industries and houses.

    1.b. Gasification Technology

Gasification is a partial oxidation process, in which most of the carbon and hydrogen in the waste is converted into the gaseous form (called syngas), leaving a solid residue (ash or char). There are many different designs of the core gasification reactor such as fluidized bed, rotary kiln, updraft and downdraft reactors, each of which is tailored to give certain benefits when gasifying various types of wastes.

Gasification offers a variety of benefits over direct combustion of the fuel as a result of it interprets concerning eightieth of the energy within the waste fuel into energy within the gas part. The resulting syngas can be utilized in a range of applications, including steam boilers and gas engines for conversion to heat and electricity with potentially increased efficiency.

        1.c. Pyrolysis Technology

Pyrolysis could be a method during which oxygen is excluded from the reactor, which is heated externally to produce the elevated temperature environment that causes the organic solids (waste input) to breakdown via physical and chemical processes into 3 products; solid char, pyrolysis oil and pyrolysis gas with the proportions of each being governed by the operating temperature within the pyrolysis reactor.

There is a definite quantity of bewilderment regarding the variations between transformation and chemical change with some individuals basic cognitive process that they're an equivalent. The true transformation could be a low-temperature thermal conversion technology that operates with an air-free atmosphere and produces a primary liquid product additionally as gas and solid part product. If pyrolysis is operated at high temperature (>800ᵒC) then the primary product becomes syngas, but the process will also produce liquid and solid phase products in lesser amounts.

      2. Biochemical Conversion of Waste to Energy

The biochemical conversion uses biocatalysts, such as enzymes, in addition to heat and other chemicals, to convert the carbohydrate portion of the biomass (hemicellulose and cellulose) into an intermediate sugar stream. These sugars square measure intermediate building blocks which will then be soured or with chemicals catalyzed into a variety of advanced biofuels and added chemicals.

          2.a Anaerobic Digestion

Anaerobic digestion is a process where biodegradable material is breakdown through microbes in the absence of oxygen. Special reactors are used for digestion process and controlled specific conditions are provided inside reactors such as pH, moisture content and temperature, etc. The purpose of these conditions is to provide a favorable environment to microbes and allow them to increase their number and to enhance the degradation process to produce methane.

Anaerobic digestion basically consists of three steps. In the first step, organic material is prepared through sorting, segregation and size reduction. In the second step, favorable environmental conditions are provided to ensure digestion process through microbes such as pH up to 6.7 and maintain temperature about 55-60 ᵒC. These components are well mixed for approximately 5-10 days, but in colder climate slurry is mixed at low temperature for a long time. In the third step, the residual sludge is disposed of, if it is contaminated, after treatment it is disposed of and it is an extra step.

           2.b. Fermentation

At its most basic, fermentation is the use of yeasts to convert carbohydrates into alcohol, most notably ethanol, also called bioethanol. The total process involves several stages. In the initial stage crop materials are fine or ground and combined with water to make a suspension. Heat and enzymes are then applied to break down the ground materials into a fine slurry. Other enzymes are added to convert starches into glucose sugar. The sugary slurry is then pumped into a fermentation chamber to which yeasts are added. After about 48-50 hours, the fermented liquid is distilled to divide the alcohol from the solid materials left over.