BIOMASS ENERGY BY SIENG LY & JOHN DEBUQUE

ADVANTAGES OF BIOMASS  Biomass used as a fuel reduces need for fossil fuels for the production of heat, steam, and electricity for residential, industrial and agricultural use.  The crops used to produce biofuels can be grown almost anywhere.  Help most countries reduce their dependence on imported oil.  Can make use of agricultural, timber and urban waste.  The rate of harvesting and conversion of these plants to biofuels does not exceed the rate at which they are replenished by new plant grow and there is no net increase in Carbon Dioxide emissions. BBiomass used as a fuel reduces need for fossil fuels for the production of heat, steam, and electricity for residential, industrial and agricultural use. TThe crops used to produce biofuels can be grown almost anywhere. HHelp most countries reduce their dependence on imported oil. CCan make use of agricultural, timber and urban waste. TThe rate of harvesting and conversion of these plants to biofuels does not exceed the rate at which they are replenished by new plant grow and there is no net increase in Carbon Dioxide emissions.

DISADVANTAGES  Land used for energy crops maybe in demand for other purposes, such as faming, conservation, housing, resort or agricultural use.  Expanding the area of land devoted to growing biofuels crops can degrade and decrease the Earth’s biodiversity  There could be growing competition between using land to grow crops for food and for biofuels.  Ethanol, as a biodiesel is terribly inefficient when compared to gasoline, and it often has to be mixed with some gasoline to make it work properly anyway  Not only does it take a lot more fuel to do the same job as using conventional fuels, but it also creates environmental problems of its own. To produce enough lumber to power a nation full of vehicles or even a power plant, companies would have to clear considerable forest area..  Combustion of biomass products require some land where they can easily be burn.

CONSUMPTIO AND USAGE

CONSUMPTION AND USAGE

SOURCES

EFFICIENCY AND COST

EFFECIENCY AND COST

EQUIPMENT (EXTRACTION)  There are two methods of generating energy out of biomass materials; wet and dry process.  Dry processes; Combustion and Pyrolysis. Wet processes; Gasification, fermentation, and anaerobic digestion.  Combustion: The most obvious way of extracting energy from biomass is combustion. Combustion systems come in a wide range of shapes and sizes burning virtually any kind of fuel, manure, to tree trunks, and scarp materials. Its mostly use for cooking and heating industrial buildings. One problem with this method is its very low efficiency. With an open fire most of the heat is wasted and is not used to cook or whatever.  Pyrolysis: Biomass energy can be produced by roasting dry woody matter like straw and woodchips. The process has been used for centuries to produce charcoal. The material is pulverized then fed into a reactor vessel and heated in the absence of air. One of the most useful products is methane, which is a suitable fuel for electricity generation using high-efficiency gas turbines.  Anaerobic digestion: Biogas is produced when wet sewage sludge, animal dung or green plants are allowed to decompose in a sealed tank under anaerobic (oxygen-free) conditions. The residue left after digestion is a potentially valuable fertilizer or compost.  Fermentation: Ethanol is produced by the fermentation of sugar solution by natural yeasts. Suitable feed stocks include crushed sugar beet and fruit. After about 30 hours of fermentation, the brew contains 6-10 per cent alcohol, which can be removed by distillation as a fuel.  Gastification: using wood produces a flammable gas mixture of hydrogen, carbon monoxide, methane and other non flammable by products. This is done by partially burning and heating the biomass (using the heat from the limited burning) in the presence of charcoal (a natural by- product of burning biomass). The gas can be used instead of petrol and reduces the power output of the car by 40%. It is also possible that in the future this fuel could be a major source of energy for power stations

ECOLOGICAL PROBLEMS  Environmental Problems Some of the common ways biomass energy is used and has been used for generations produce a high level of carbon dioxide. This occurs when wood is burned. biomass energybiomass energy It becomes more of the a problem when the wood is cut for the purpose of burning as we create more carbon dioxide while removing a living plant that helps control carbon by its very existence. Cutting down forests to use wood as a biomass fuel has damaged many third world countries that did not plan for any forest conservation or renewal. Trees in a forest capture and hold carbon. By cutting live trees and burning the wood, we double the negative affect on the environment. This is now understood and accepted but for some areas the knowledge comes too late. There are countries where the forest has been clear-cut to burn wood for heat and cooking. The resulting living conditions in a poor country are even worse once the trees are gone as land is open to flooding and erosion.  Pollution of Biomass Energy Biomass fuels such as ethanol are no less a pollutant than fossil fuels. Combustion of ethanol is incomplete and this produces the black carbon which is known to increase global warming. Use of ethanol as a gasoline additive is promoted as reducing our reliance on fossil fuels. An entire prosperous industry has grown in recent years around the production and distribution of ethanol. Though some experts claim ethanol has a damaging effect on automobile engines over time and is not better for the environment, the product continues to be used as the profits are too high to abandon.