Perspective
Rediscovering Fire
in the 21st Century
The discovery of fire gave early humans invaluable tools in
a hostile world: the gift of light, and the ability to make
food more palatable through cooking. Fire continues to be an
essential part of daily life in many developing countries —
including those with transitional economies, such as Brazil,
China and India.
In India, a country with an active space and nuclear
program, around 60 per cent of the rural population lacks
electricity, relying instead on primitive wood stoves, which
carry a heavy health risk. A 2003 report by the Intermediate
Technology Development Group suggested that indoor air
pollution from cooking stoves results in nearly 1.6 million
deaths worldwide every year.
Clean, modern technology, including the emerging fields of
biotechnology and nanotechnology, could greatly improve the
quality of life for nearly 60 per cent of humankind by
providing cleaner, safer and more effective alternatives.
As cooking and lighting account for some 75 per cent of the
total energy that rural households consume, the challenge
for scientists and technologists trying to develop cooking
and lighting technologies that meet the needs of the rural
poor is a large one. Light and heat are fundamental human
needs, but the cost of providing them to the rural poor has
been high — until now.
Three billion people in the world earn $ 1-2/day. Majority
of them live in rural areas with very primitive quality of
life. For example in India, which boasts of a very active
space and nuclear program, around 60% of rural population
have no electricity, use 180 million tons of biomass/year
for cooking via primitive wood stoves and have no clean
drinking water.
Fuelling rural stoves
Some forms of biomass, such as vegetation or animal dung, can
provide safe and convenient energy sources in the form of gaseous
and liquid fuels, although there are technological hurdles to
overcome in this area.
Biogas — a mixture of methane and carbon dioxide — for instance,
has been used for past 80 years as a fuel in rural India. The gas
is produced by mixing biomass with water in a special gas producer
or 'digester'. As the biomass degrades, the gas is given off and
can be collected. Biogas can be produced in the home, but the
systems used are inefficient. They also require considerable
amounts of cow dung and other nitrogen-rich material, which makes
them unsuitable for households with fewer than three or four
cattle.
The challenges of biogas production don't end there. Cold weather
slows fermentation and if the different types of biomass are
poorly mixed, the digestion is less efficient. Because biogas
cannot be liquefied and requires very high pressure (more than 100
atmospheres — 100 times greater than the air pressure at the
Earth's surface) to compress it, it cannot be stored for long
periods.
Research and development are needed in two areas. One is in
developing extremely efficient biogas reactors, to get as much gas
as possible from the biomass. Genetically engineered microbes, for
instance, might substantially increase the efficiency of gas
production. The second area is the development of appropriate
materials for storing biogas at medium pressures.
Recent experiments by P. Pfeifer and colleagues affiliated to
France's National Centre of Scientific Research (CNRS) show that
biogas can be stored at medium pressure (fewer than 40
atmospheres). These findings could pave the way for small utility
companies to be set up, revolutionizing the way cooking is done in
rural areas.
These companies could buy cow dung and other locally available
biomass, and use them in a high-tech biogas reactor with
sophisticated electronics-based controls and biochemical
engineering technology, to generate biogas efficiently. The
companies could then store the gas in small metal cylinders much
like the familiar propane or butane cylinders, which could be
transported to households.
Although much too costly for most rural households in countries
such as India, the entire system would be affordable for a small
rural utility company.
Such companies could also use biomass to produce liquid fuels such
as ethanol and bio-diesel — which is obtained from plant oils.
Another fuel is pyrolysis oil, produced when dry biomass is
rapidly heated to about 600 degrees Celsius in the absence of air.
The vapors condense to form the pyrolysis oil, which is similar to
diesel.
Such a
project could be made feasible by local activities including
planting crops such as sweet sorghum that can be used for both
food and fuel, meaning that food production is not compromised.
Another option is to cultivate high-yielding hybrids of bio-diesel
crops, such as Karanja and Jatropha, whose seeds yield oil.
But stoves need to be adapted to run on bio-diesel and pyrolysis
oil. These fuels are sticky and tend to form a lot of soot, so
sophisticated combustion science and technology is required to
produce an efficient blue flame.
Getting such stoves to burn with a clean flame will also help in
developing 'combustors' that produce light by a flame heating up a
lace-like envelope of material, called a mantle, which surrounds
it. This heated mantle glows to produce light.
Looking for light
Adequate lighting is a basic human requirement and should be a
part of any government's minimum needs program. Light is produced
either by electricity, or by burning a fuel such as kerosene or
oil to produce a glowing flame.
Many rural people rely on lights that burn liquid fuel. One of the
best systems is a pressurized lamp with a mantle, which is lit by
kerosene gas. Amazingly, these mantles (made of an oxide called
thoria mixture) have not changed at all since they were developed
in Germany in the late 1880s.
The mantles are about one-third as efficient as a 100-watt light
bulb at generating light.
With today's level of materials technology, it should be possible
to develop new materials for more efficient mantles. In the 1980s,
researchers found that coating the mantles with alternative
materials like ytterbium, a metal used in lasers and x-ray tubes,
produces promising results. With the latest advancement of
materials technology it will be much easier to tailor-make the
materials for mantles.
Current mantles are also brittle and break easily. Having to
replace them increases the cost of running a lantern. So there is
a need to develop stronger and more durable materials such as
those based on ceramics and carbon composites. These materials can
withstand high temperatures and hence will not break. With such
mantles, liquid-based lighting could become robust as well as
efficient.
It might even be possible to develop mantles that are as efficient
as light bulbs. A liquid fuel lamp with an efficient mantle and
running on locally made fuels like ethanol, bio-diesel or
pyrolysis oil could be an excellent distributed light source for
rural areas.
One of the most efficient lighting systems in the world is the
glow of the firefly, created when two chemicals called luciferase
and luciferin react. The energy from this reaction is converted
directly into light. Scientists estimate that it is around 85-90
per cent efficient at converting chemical energy into light. A
light bulb's efficiency is just 7-10 per cent.
Imitating this mechanism could produce the ultimate light source.
At the moment it is no more than a dream, but a solar-powered unit
producing luciferase and luciferin from biomass could one day be a
reality.
As most rural areas have no access to grid electricity, much
research and development around the world is being directed at
developing decentralized sources of electricity, which range from
5-10 kilowatt (providing light to 30-60 rural households) to 10
megawatt capacity (enough power for a rural population of
200,000).
These systems include: county-level power plants, biomass-gasifier-based
(gasifiers produce a mixture of carbon monoxide and hydrogen gas
which is used to run an internal combustion engine) equipment and
innovative technologies such as gas-powered 20-30 kilowatt
micro-turbines and steam engines with a small 30 kilogramme unit
that can produce six kilowatts of electric power.
Small but perfectly productive
As well as electricity from local organic materials, there is
promising research and development in three micro-technologies for
producing electricity. These are human muscle-powered lighting
systems, thermoelectric devices and miniature 'nano-engines'.
For example, recent advances in lightweight and highly efficient
'permanent magnet direct current' (PMDC) motors have made it
possible for people to use physical effort to produce a small
amount of electricity. This electricity, when combined with
rechargeable batteries, can power some of the most efficient and
long-lasting light-producing devices — light-emitting diode (LED)
systems.
Two companies — Freeplay in Europe and Light up the World in
Canada – have pioneered this system. At the moment, the technology
is expensive, with a handheld flashlight costing US$50. Research
is needed to develop three specific components: cheap LED units,
lighter and more efficient PMDC motors, and efficient ways of
storing the electric charge so it can be discharged slowly.
Using this approach, bicycle-powered units on which household
members can take turns to charge the battery, could produce 3-4
hours' worth of light.
The simple biomass cooking stoves now prevalent in rural areas —
inefficient and smoky, with about 10-15 per cent cooking
efficiency — could also be given a radical overhaul by new
developments. Attaching a device that converts heat into
electricity to such a stove, for instance, could generate 50-60
watts of power for lighting.
This power could be used to generate light or to run a small fan
to increase the stove's efficiency, as well as ensure that less
soot is produced.
Recent developments in nanotechnology and new materials have also
shown that efficient devices that also convert heat directly into
energy can be developed. For instance, coin-sized 'nano-engines'
that can produce ten watts of energy from biomass fuels such as
ethanol, are already being developed by researchers at the
US-based Massachusetts Institute of Technology and University of
California, Berkeley for defence purposes and to power mobile
phones..
The devices could also power LED lamps, revolutionizing rural
lighting. Such a compact system would bypass the need for bulky
and costly batteries, since the liquid fuel itself would store the
energy. This could result in an extremely compact and lightweight
decentralized lighting source.
Any technology becomes attractive if it is economically viable,
and increasing the efficiency of a technology can make it more
economical. This is true for cooking and lighting technology for
rural areas. Once the technology is available, industry can find
ways to reduce the cost of production and bring the price within
reach of the rural poor.
In rural India, preliminary economic analyses show that lighting
and cooking technologies based on liquid and gaseous fuels could
become a US$6 billion a year industry. The same could be true for
other developing countries.
These technologies could help increase the quality of life of
rural people, and create wealth through fuel production and use.
Investing in such technology could help to bring three billion
people into the mainstream of development — which is the best way
to create a just and sustainable world.
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