Biofuel

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(Redirected from Biomass fuel)

Biofuel is any fuel that derives from biomass — recently living organisms or their metabolic byproducts, such as manure from cows. It is a renewable energy source, unlike other natural resources such as petroleum, coal and nuclear fuels. The carbon in biofuels was recently extracted from atmospheric carbon dioxide by growing plants, so burning it does not result in a net increase of carbon dioxide in the Earth's atmosphere. As a result, biofuels are seen by many as a way to reduce the amount of carbon dioxide released into the atmosphere by using them to replace non renewable sources of energy.

Agricultural products specifically grown for use as biofuels and waste from industry, agriculture, forestry, and households — including straw, lumber, manure, sewage, garbage and food leftovers — can be used for the production of bioenergy. Currently, most biofuel is burned to release its stored chemical energy. Research into more efficient methods of converting biofuels and other fuels into electricity utilizing fuel cells is an area of very active work. Bioenergy covers about 15% of the world's energy consumption. Most bioenergy is consumed in developing countries and is used for direct heating, as opposed to electricity production. However, Sweden and Finland supply 17% and 19% respectively, of their energy needs with bioenergy, quite high for industrialized countries. Biomass can be used both for centralized production of electricity and district heat, and for local heating.

Contents

Classes of Biofuels

Solid

There are many forms of solid biomass that are combustible as a fuel1 such as:

Dried compressed peat is also sometimes considered a biofuel. However it does not meet the criteria of being a renewable form of energy, or of the carbon being recently absorbed from atmospheric carbon dioxide by growing plants. Though more recent than petroleum or coal, on the time scale of human industrialisation it is a fossil fuel and burning it does contribute to atmospheric CO2.

Liquid

There are also a number of liquid forms of biomass that can be used as a fuel:

Gaseous

Other

One company, GreenFuel Technologies Corporation, has developed a patented bioreactor system that utilizes nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, bio-gas (similar to natural gas), and a dry fuel comparable to coal.

Energy content of Biofuel

fuel type Specific Energy Density (J/kg) Volumetric Energy Density (J/l)
wood fuel  16 × 106 - 21 × 106  
dried plants    
animal waste    
chaff    
bagasse  9.6 × 106  
ethanol  23.4 × 106 - 26.8 × 106  23.4 x 106
gasoline (comparison)  45.0 x 106  32.0 x 106
methanol  19.9 × 106 - 22.7 × 106  15.9 × 106
butanol  36.0 × 106  29.2 x 106
vegetable oil    
Biodiesel  37.8 x 106  33.3 x 106 - 35.7 x 106
Methane  55 × 106 - 55.7 × 106  Compression Dependent
Hydrogen  120 × 106 - 142 × 106  Compression Dependent

Dissemination mechanisms

Most biofuels have a low specific energy density compared to fossil fuels. This means that biomass energy schemes must work at a local level as their success depends on well-structured and sustainable fuel supply networks from local producers.

Small scale use of biofuels

One widespread use of biofuels is in home cooking and heating. Typical fuels for this are wood, charcoal or dried dung. The biofuel may be burned on an open fireplace or in a special stove. The efficiency of this process may vary widely, from 10% for a well made fire (even less if the fire is not made carefully) up to 40% for a custom designed charcoal stove1. Inefficient use of fuel may be a minor cause of deforestation (though this is negligible compared to deliberate destruction to clear land for agricultural use) but more importantly it means that more work has to be put into gathering fuel, thus the quality of cooking stoves has a direct influence on the viability of biofuels.

Unfortunately, much cooking with biofuels is done indoors, without efficient ventilation, and using fuels such as dung which cause most airborne pollution. This can be a serious health hazard; 1.5 million deaths were attributed to this cause by the World Health Organisation as of 20002. There are various responses to this, such as improved stoves, including those with inbuilt flues and switching to alternative fuel sources. Most of these responses have difficulties. One is that flues are expensive and easily damaged. Another is that alternative fuels tend to be more expensive, but the people who rely on biofuels often do so precisely because they cannot afford alternatives.3 Organisations such as Intermediate Technology Development Group work to make improved facilities for biofuel use and better alternatives accessible to those who cannot currently get them. This work be done through designing improved ventilation, a switch to different usage of biomass such as through the creation of biogas from solid biomatter, or a switch to other alternatives such as micro-hydro power.

Implementation of biofuels use on the national level

On the other hand, recognizing the importance of bioenergy and its implementation, there are international organizations such as IEA Bioenergy, established in 1978 by the International Energy Agency (IEA), with the aim of improving cooperation and information exchange between countries that have national programs in bioenergy research, development and deployment.

See also

References

  1. Biomass Technical Brief, Simon Ekless, Intermediate Technology Development Group, retrieved 1 January 2005 from http://www.itdg.org/docs/technical_information_service/biomass.pdf.
  2. Smoke — the killer in the kitchen, Intermediate Technology Development Group, 19 March 2004, retrieved 1 January 2005 from http://www.itdg.org/?id=smoke_report_1
  3. Reducing exposure to indoor air pollution, Intermediate Technology Development Group, 19 March 2004, retrieved 1 January 2005 from http://www.itdg.org/?id=smoke_report_3

External links

Retrieved from "http://en.freepedia.org/Biofuel.html"


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