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Biomass as an Alternative Fuel for Generating Electricity
Written by : Eng. Fahad A. Rafai
Electrical energy has many different sources and can be produced in different ways. However, countries are competing to produce energy and trying to have unlimited sources for producing it. Moreover, producing electrical energy using normal fossil fuels, such as, oil, coal and so on has some major problems, from the cost of fuel to the pollution. At the end of the last century, engineers have started looking for new sources which have the same advantages as the fossil fuels while avoiding their disadvantages. In fact, there some sources were already known from the natural, one of them is called renewable energy. It called renewable because it will not run out and can be reproduced . This kind of energy has different types and can be found in different forms, for instance, wind energy, solar energy, hydroelectric energy, biomass energy and so on.
"In the United States, since 1973 there has been a dramatic increase in biomass use, especially in thermal and electrical applications of wood residues" . This article will examine the using of biomass energy as an alternative fuel in the electricity industry. Initially, it will cover a brief background on biomass and include its sources and history. Secondly, the using of biomass for generating electricity in power plants will be investigated. Then, some of the advantages and disadvantages of using biomass will addressed . A conclusion will complete the article.
Biomass in Brief
Biomass is one of the oldest sources of energy in the world. Although we have been using it all the time, it may have been never heard about its scientific name. Biomass known as living material or specifically, it is the conversion of the stored energy in the dead trees, tree branches, wood, crops and even animals into energy so that we can use it. For example, "The major categories of biomass fuels used in the United States today include, wood processing residues, in-forest residues, agricultural residues and urban wood residues" .
As a result, biomass energy can be found easily in any place and any time. In fact, biomass will not be useful for producing electrical power energy unless converted into another form. Consequently , if any company wants to use biomass as a source of energy instead of oil or gas, it will need to collect the biomass ( plants, wood and so on ) and burn it in special places, then the heat of this burning can be used in a steam turbine to generate electricity. In the same way, power plants can use biomass in a different process which called Gasification. In this case, biomass is going to be heated at very high temperature degrees to produce flammable gases which can be used to rotate the turbine and produce electricity. According to the California Energy Commission web site, California produces about 60 million tons of biomass every year, which means around 2,000 megawatt of electrical power. In fact, this power is enough to market and could supply about two million homes. 
Although biomass energy has been used many years ago, some countries still use it as a fuel in electrical power generation until now. In contrast, some countries stopped using it because of its environmental impacts. It has been said that biomass has been contributing to the environmental pollution. However, the benefits of this energy encouraged some societies to use it, for instance, "BEG (The Biomass Energy Group) has concluded that a biomass industry in Scotland has the potential to supply as much as 450 MW of electricity from the wood fuel resource while employing over 2,000 people and stimulating other sectors of the Scottish economy" . In addition EIA (The Energy Information Administration) estimation of biomass resources shows that there are 590 million wet tons (equivalent to 413 million dry tons) of biomass available in the United States on an annual basis . In fact, biomass can be used in power plants using different methods and each method has its own efficiency and productivity.
Electrical Power Generation from waste
Generating electricity in power plants using fossil fuel is the most popular method in the world. However, using biomass to generate electricity can be efficient with some regulations and limitation . There are four main types of biomass power systems: direct-fired, co-fired, gasification, and modular systems. Most of the power plants which use biomass are direct-fired systems which use the same technique of fossil-fuel fired power plants. Figure1 shows how to use biomass as fuel in power plants.
The biomass is burned in a boiler to produce high-pressure steam. This steam is introduced into a steam turbine, where it flows over a series of aerodynamic turbine blades, causing the turbine to rotate. The turbine is connected to an electric generator, thus, as the steam flow causes the turbine to rotate, the electric generator turns and electricity is produced. Biomass power boilers are typically in the 20-50 MW range, compared to coal-fired plants in the 100-1500 MW range . Therefore, it was suggested that in some power plants, such as, the Bay Front Station in Ashland in the United States it would beneficial to operate the units ( turbines) using coal in the peak periods and using biomass in the low load periods . However, direct combustion of wood to generate electrical power is the most advanced method at present. Also, it might be not competitive unless used in combination with other sources, such as coal and gas .
Figure 1: Using Biomass to produce electricity in power plants. 
Advantages of using Biomass:
Using biomass as an alternative energy to generate electrical power has some economical benefits. Moreover, it can be a useful source for energy in the small societies or small industrial areas. In contrast, even developed countries can use this source to compensate for the lack of the other sources, such as, oil, gas or coal. One of the most important advantages of biomass is its cheap prices; also it is a readily available source of energy. In addition, it is a continuous and long term source, it can be found easily, any time and almost anywhere. One more advantage for biomass power plants is helping to reduce the unemployment in various countries, Shiona Baird, MSP, the Scottish Green Party's energy spokeswoman, said to The Scotsman:
"The new power station, and the considerable number of jobs that it will create, is good news" . This contribution by establishing a biomass power plant at Lockerbie, Dumfriesshire in Scotland it will support the economy in the UK and will help the government in its fight against unemployment.
Disadvantages of using Biomass
Like any renewable source, biomass has some disadvantages for using it to generate electrical power. Does biomass affect the environment? This question has been asked many times. In fact, many people are concerned about the contribution of biomass in the global warming because the combustion of biomass will produce carbon into the air. However, this point of view could be wrong if you understand the biomass cycle. Figure 2 describes the carbon cycle and how biomass plays main role in it. Although biomass can be found anywhere in the world, some places like desert areas in the middle east such as Saudi Arabia, possibly will face difficulties to get enough plant and trees to be used as a biomass source. As a result, the transportation of the plant and tress to theses areas will be costly and using biomass in this case will be worthless.
Figure2: Carbon cycle .
To sum up, this article has shown that using biomass in industry and specifically in power plants to produce electrical power, would help many people to find jobs and could help the governments to diminish the unemployment rates. Moreover, every year, countries spend billions of dollars to sell oil or gas for generating electricity, for this reason, it will be more economical and useful if biomass has been used. In the electricity markets it can be said: energy is money. And by using biomass this saying can be verified. Moreover, biomass can be used in different methods which mean more flexibility. Although the power plants which use biomass will produce less power than that power plant which uses fossil fuel, still using small biomass units in the villages and small towns would be more economical than using normal fossil units.
1. Black, E (2005) Wood-fuelled power station to be UK's first, The Scotsman, http://thescotsman.scotsman.com (28 August 2006)
2. Haq, Z, (2002) The Energy Information Administration, Biomass for Electricity Generation
3. Morris, G. (1999) The Value of the Benefits of U.S. Biomass Power, National Renewable Energy Laboratory, Berkeley, California, USA.
4. Overend, R.P. (1996) Production of Electricity from Biomass Crops – US Perspective. National Renewable Energy Laboratory, Golden, Colorado, USA
5. Slesser, M & Lewis, C (1979) Biomass as a Nonfossil Fuel Source, A Halsted Press Book, p. 141.
6. (2005) Promoting and Accelerating the Market Penetration of Biomass Technology in Scotland, Scottish Executive
7. Biomass, Energy matters
http://library.thinkquest.org/20331/types/biomass/ ( 28 August 2006)
8. ( 2002) Biomass Energy, Energy Quest
9. Figure 1 : BBC website : http://news.bbc.co.uk/1/hi/sci/tech/4948052.stm