May 21, 2019
The next day in the field of energy lies in biomass. Biomass is the oldest and most widespread Renewable Energy Source. The primitive man used to heat and cook, used Heat from the burning of wood. Until today, mainly the rural populations of Africa, India, Latin America and Europe, to warm up and cook using wood, plant residues (straw, sawdust, nuts or pits, etc.) and animal waste manure, animal fat, waste, etc.).
By biomass we designate any material produced by plant or animal organisms and can be used as fuel for energy production. Biomass has stored Energy, either directly from the Sun (Photosynthesis – plant-based biomass) or indirectly (animal-derived biomass – energy-using animal waste). This stored energy is exploited in the cogeneration units of electric and thermal energy.
Examples of biomass are as follows:
-Articles of agricultural crops, such as branches, leaves, straw, logging or forest cleansing, woodworking etc.
-Options of agricultural processing units, such as olive kernels, fruit kernels, cotton gin, olive presses etc.
– Animal waste, such as waste dumplings, pigs, poultry, slaughterhouses, food industries, etc.
-Energy plants of one year or perennial, such as sorghum, oilseed rape, wild boar, eucalyptus.
Biomass, as a renewable source, is subject to the favorable provisions of the existing electricity generation legislation. The electricity generated by it is sold to the Electricity Market Operator (LAGIE) for 20 years at a particularly privileged and stable price. On the other hand, whatever form of biomass we choose as a raw material for our productive unit, it will have a low energy content compared to fossil fuels. Therefore, large quantities of raw material are required, especially in volume. We also have to deal with the expected difficulties in collecting and transferring it to our production unit. Periodicity in the appearance of biomass, depending on its origin, necessitates the construction of storage systems. Finally, the cost of converting the raw material into more user-friendly forms often costs the overall operating cost. However, research and technological progress over the last 10 years, coupled with securing guaranteed market prices for energy produced, have made biomass energy conversion technologies extremely attractive globally. The prospects for bioenergy are becoming ever greater and more promising. In the most advanced economies, it is expected to cover a significant portion of energy production in the future.
Disadvantages related to conventional fuels
At each biomass plant, irrespective of technology, the economic viability of the investment is primarily based on the solution of the following fundamental parameters:
The biomass energy utilization technologies for the production of electricity and thermal energy are divided into three general categories, which are summarized below.
Anaerobic digestion is a natural process of degradation of organic substances with the help of a wide range of microorganisms, in the absence of oxygen. The products produced are a mixture of flammable and non-gaseous and a solid soil nutrient-rich nutrient for plants. The gas mixture contains inter alia methane (CH4), carbon dioxide (CO2) and water vapor (H2O), and in smaller amounts ammonia (NH3), nitrogen (N2), hydrogen (H2), hydrogen sulfide (H2S, These gases, after being cleaned and dehumidified, are driven to an internal combustion engine to produce electric and thermal energy, and could be fed into the natural gas network, as is the case in some European countries.
An abundance of agricultural crops, energy crops, stockpiles of livestock and poultry farms, slaughterhouses, olive mills, etc. can be used to feed the anaerobic digester. It is the most expensive and the oldest method of cogeneration of biomass energy and, according to legislation, ensures a higher feed-in tariff than the other two methods that follow.
By gasification we convert any carbon-rich organic feedstock (C) into fuel gas. Gasification is a relatively new biomass energy utilization technology, although the overall technology is quite old with more than 180 years of life. During the B? World War and Occupation, in the absence of oil, many cars were driven by gas produced from wood or gas (gasozen). The total installation cost of such a unit is lower than a corresponding anaerobic digestion unit, while the electricity and heat yields are comparable. However, there is a limitation on the feedstocks of the gasifier. Vegetable residues or waste which are specially processed (dried and chopped) are usually used, so that they have a moisture content of less than 20% before being introduced into the gasifier.
The whole process is based on limiting the amount of oxygen inside the gasifier to incomplete combustion of the biomass. This process, which is characterized as partial oxidation, also imparts the required heat to the system. The raw material is broken down by the existing heat inside the gasifier, resulting in a series of chemical reactions that eventually produce a flammable gas mixture. This mixture contains inter alia carbon monoxide (CO), hydrogen (H2), methane (CH4) and smaller amounts of carbon dioxide (CO2) and nitrogen (N2). After purification, the mixture can feed a generating set for cogeneration of electricity and heat.
By the method of direct combustion of biomass, heat is produced which vaporizes water. The steam then drives a gas turbine coupled with an electric generator, generating electricity. Although cheaper to a total installation cost than the two previous methods, biomass burning is characterized by a lower efficiency factor for electricity generation than the previous two technologies. This method is more cost-effective for the production and utilization of heat (heating of industrial units, settlements, greenhouses, etc.) Due to relatively low installation costs, in colder than our own countries, where the heat produced can be utilized for several months, the economic returns of such units are quite attractive