Biomass briquettes

[edit] What are biomass briquettes?

Biomass briquettes are a biofuel substitute made of biodegradable green waste with lower emissions of greenhouses gases and carbon dioxide then traditional fuel sources. This fuel source is used as an alternative for harmful biofuels. Briquettes are used for heating, cooking fuel, and electricity generation usually in developing countries that do not have access to more traditional fuel sources. Biomass briquettes have become popular in developed countries due to the accessibility, and eco-friendly impact. The briquettes can be used in the developed countries for producing electricity from steam power by heating water in boilers.

The briquettes are fired with coal in order to create the heat supplied to the boiler. Biomass briquettes are built from recycled green waste, producing less greenhouse gas admissions because the matter has already completed part of the carbon cycle.

[edit] Composition of biomass briquettes

Biomass briquettes, mostly made of green waste and other organic materials, are commonly used for electricity generation, heat, and cooking fuel. These compressed compounds contain various organic materials, including rice husk, bagasse, ground nut shells, municipal solid waste, agricultural waste. The composition of the briquettes varies by area due to the availability of raw materials. The raw materials are gathered and compressed into briquette in order to burn longer and make transportation of the goods easier.These briquettes are very different from charcoal because they do not have large concentrations of carbonaceous substances and added materials. Compared to fossil fuels, the briquettes produce low net total greenhouse gas emissions because the materials used are already a part of the carbon cycle.

[edit] Production of biomass briquettes

One of the most common variables of the biomass briquette production process is the way the biomass is dried out. Manufacturers can use torrefaction, carbonisation, or varying degrees of pyrolysis. Researchers concluded that torrefaction and carbonisation are the most efficient forms of drying out biomass, but the use of the briquette determines which method should be used.

Compaction is another factor affecting production. Some materials burn more efficiently if compacted at low pressures, such as corn stover grind. Other materials such as wheat and barley-straw require high amounts of pressure to produce heat. There are also different press technologies that can be used. A piston press is used to create solid briquettes for a wide array of purposes. Screw extrusion is used to compact biomass into loose, homogeneous briquettes that are substituted for coal in co-firing. This technology creates a toroidal, or doughnut-like, briquette. The hole in the center of the briquette allows for a larger surface area, creating a higher combustion rate.

[edit] The use of biomass briquettes in co-firing

Co-firing relates to the combustion of two different types of materials. The process is primarily used to decrease CO2 emissions despite the resulting lower energy efficiency and higher variable cost. The combination of materials usually contains a high carbon emitting substance such as coal and a lesser CO2 emitting material such as biomass. Even though CO2 will still be emitted through the combustion of biomass, the net carbon emitted is nearly negligible.

This is due to the fact that the material gathered for the composition of the briquettes are still contained in the carbon cycle whereas fossil fuel combustion releases CO2 that has been sequestered for millennia. Boilers in power plants are traditionally heated by the combustion of coal, but if co-firing were to be implemented, then the CO2 emissions would decrease while still maintaining the heat inputted to the boiler. Implementing co-firing would require few modifications to the current characteristics to power plants, as only the fuel for the boiler would be altered. A moderate investment would be required for implementing biomass briquettes into the combustion process.

Co-firing is considered the most cost-efficient means of biomass. A higher combustion rate will occur when co-firing is implemented in a boiler when compared to burning only biomass. The compressed biomass is also much easier to transport since it is more dense, therefore allowing more biomass to be transported per shipment when compared to loose biomass. Some sources agree that a near-term solution for the greenhouse gas emission problem may lie in co-firing.

[edit] Biomass briquettes compared to coal

The use of biomass briquettes has been steadily increasing as industries realise the benefits of decreasing pollution through the use of biomass briquettes. Briquettes provide higher calorific value per dollar than coal when used for firing industrial boilers. Along with higher calorific value, biomass briquettes on average saved 30–40% of boiler fuel cost. But other sources suggest that co-firing is more expensive due to the widespread availability of coal and its low cost. However, in the long run, briquettes can only limit the use of coal to a small extent, but it is increasingly being pursued by industries and factories all over the world. Both raw materials can be produced or mined domestically in the United States, creating a fuel source that is free from foreign dependence and less polluting than raw fossil fuel incineration.

Environmentally, the use of biomass briquettes produces much fewer greenhouse gases, specifically, 13.8% to 41.7% CO2 and NOX. There was also a reduction from 11.1% to 38.5% in SO2 emissions when compared to coal from three different leading producers, EKCC Coal, Decanter Coal, and Alden Coal. Biomass briquettes are also fairly resistant to water degradation, an improvement over the difficulties encountered with the burning of wet coal. However, the briquettes are best used only as a supplement to coal. The use of co-firing creates an energy that is not as high as pure coal, but emits fewer pollutants and cuts down on the release of previously sequestered carbon. The continuous release of carbon and other greenhouse gasses into the atmosphere leads to an increase in global temperatures. The use of co-firing does not stop this process but decreases the relative emissions of coal power plants.

--Richimachinery

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[edit] External References

^ "Feed Biomass." Productieproces van biomassapellets. Web. 30 Nov. 2010.

^ Chohfi, Cortez, Luengo, Rocha, and Juan Miguel. "Technology to Produce High Energy Biomass Briquettes." Techtp.com. Web. 30 Nov. 2010.

^ Mani, Sokhansanj, and L.G. Tabil. "Evaluation of compaction equations applied to four biomass species.Web. 30 Nov. 2010.

^ "Biomass Briquetting: Technology and Practices - Introduction." Centre for Ecological Sciences INDIAN INSTITUTE OF SCIENCE BANGALORE. Web. 04 Dec. 2010.