From Wikipedia, the free encyclopedia.
This article is about the general topic of biofuel. For an
article on the specific type used in vehicles, see Biodiesel.
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.
Agricultural products specifically grown for use as biofuels
include corn
and soybeans,
primarily in the United
States, as well as flaxseed
and rapeseed,
primarily in Europe.
Waste from industry, agriculture,
forestry,
and households can also be used to produce bioenergy; examples
include straw,
lumber,
manure,
sewage,
garbage
and food leftovers. Most biofuel is burned to release its stored
chemical energy, though research is active into more efficient
methods of converting biofuels and other fuels into electricity
utilizing fuel
cells.
Biomass can be used both for centralized production of
electricity and district heat, and for local heating. As of 2005,
bioenergy covers approximately 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% [1]
respectively, of their energy needs with bioenergy, a high figure
for industrialized countries.
The production of biofuels to replace oil and natural gas is in
active development, focusing on the use of cheap organic matter
(usually cellulose,
agricultural and sewage waste) in the efficient production of liquid
and gas biofuels which yield high net
energy gain. 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.
 | 1 Classes
of Biofuels
 | 1.1 Solid |
| 1.2 Liquid |
| 1.3 Gaseous |
| 1.4 Other |
|
| 2 Energy
content of Biofuel |
| 3 Examples
| 3.1 Problems
and solutions |
| 3.2 International
efforts |
| 3.3 See
also |
| 3.4 References |
| 3.5 External
links |
|
|
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:
| Oils and gases can be produced from various wastes:
|
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. Coal is a black mineral made by fire.
]
Energy content of Biofuel
Examples
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.
"American homeowners are turning to burning corn in special
stoves to reduce their energy bills. Sales of corn-burning stoves
have tripled this year [...] Corn-generated heat costs less than a
fifth of the current rate for propane and about a third of
electrical heat" [3].
- Use on farms
In Germany small scale use of biofuel is still a domain of
agricultural farms. It is an official aim of the German government
to use the entire potential of 200,000 farms for the production of
biofuel and bioenergy. (Source: VDI-Bericht "Bioenergie -
Energietrδger der Zukunft".
Problems and solutions
Unfortunately, much cooking with biofuels is done indoors,
without efficient ventilation, and using fuels such as dung causes
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 2000 2. 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 is done through improving
ventilation, switching to different uses of biomass such as the
creation of biogas from solid biomatter, or switching to other
alternatives such as micro-hydro
power.
International efforts
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
- Biomass
Technical Brief, Simon Ekless, Intermediate
Technology Development Group, retrieved 1
January 2005
from http://www.itdg.org/docs/technical_information_service/biomass.pdf.
- 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
- 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
