B
Baphomet
Guest
WHAT'S NEXT: Drip, Drip, Zap: Electrical Current From Flowing Water
January 1, 2004
By IAN AUSTEN
N.Y. Times
MOST people are familiar with how water can be used to make
electricity. Allow it to flow downhill past the blades of a
turbine, turning them as it rushes by. Attach the turbine
to a generator, and power is generated - hydroelectric
power, the kind produced by the megawatt at dams around the
world.
But there is another, far less familiar way of generating
electricity from the movement of water. Dripping it through
microscopic channels - the kind found by the hundreds of
thousands in a standard ceramic laboratory filter, say -
creates a buildup of positive and negative charges. Tap
into these charges with electrodes, and current will flow.
Researchers at the University of Alberta in Canada have
made such an electrical generator, inserting a filter into
the bottom of a beaker, attaching two coils of wire to the
filter to serve as electrodes, and filling the beaker with
water.
Unfortunately, the amount of electricity produced by this
"electrokinetic" method is extremely small - it won't do
much more than nudge the needle of an extremely sensitive
voltage meter. But the researchers say the method holds
promise and may someday be used to power small electronic
devices. If the materials can be successfully scaled up to
giant proportions, they say, it might even be used to build
power plants free of both pollution and moving parts.
Larry W. Kostiuk, a professor of mechanical engineering at
the university and the co-author of a recent paper on the
water generator, said the process would never overtake
conventional ways of making electricity, including
electrochemical batteries. But he added, "We find it
exciting that we have revived an area of science that's
been forgotten."
Edmonton, site of the University of Alberta campus, is
better known for its links to the oil and gas industry than
for research on alternative sources of energy. Until
recently Dr. Kostiuk's research in his department was
devoted to studying flares used at oil wells to burn
surplus gases.
But after Dr. Kostiuk agreed during a sabbatical to become
the chairman of the mechanical engineering department, he
realized that he had one shortcoming for his new post. "I
was a bit of a lab rat," he said. "I wasn't the most social
of people. So when I came back I thought I had to find out
what everybody was doing in the department."
Dr. Kostiuk began stopping by the offices of other faculty
members, asking them to explain their work. A particularly
long session unfolded with Daniel Y. Kwok, an assistant
professor who studies the interaction between materials at
the molecular level as part of his research into
nanotechnology. Like other researchers in that field, he
measures voltage changes caused by the interaction of
liquids with solids.
To Dr. Kwok, such measurements were mostly a way to study
the interactions, not experiments in generating
electricity. But Dr. Kostiuk was interested in the
electrical characteristics of the interaction.
"If you draw current, does it kill the whole system? Does
it start strong but drop off rapidly?" Dr. Kostiuk recalled
asking. "The more I asked Daniel these and other questions,
the more uncertain he was about what the voltage
characteristics would be."
In an effort to address those questions, Dr. Kwok had a
graduate student search through scientific papers. When the
student came up empty-handed, the filter-in-the-beaker
experiment was born. "It was a really, really bad
experiment," Dr. Kostiuk said. "I'm not sure the best way
to build electrodes is by just coiling up a few inches of
wire."
But the experiment did show that the water passing through
the pores generated a current. As has long been known, the
movement of water past a solid like the filter causes ions
on the filter's surface to become negatively charged, while
adjacent ions in the water are positively charged. The
experiment revealed that the tiny channels of the ceramic
filter - it had about 450,000 - align the ions to create a
negative end and a positive end, allowing a current to
flow.
Despite the crudeness of their materials (Dr. Kostiuk said
the filter used in the experiment was chosen only because
it was at hand), the researchers found that several factors
affected the electricity that emerged from their
no-moving-parts generator. In particular, the type of water
used made a significant difference.
Distilled water, which has relatively few ions, created
higher voltages but very little current in comparison with
Edmonton's tap water. Salt water made lower voltages but
higher current. Perhaps more important, the experiment
suggested that the easiest way to create more power is
simply to run more water through more microchannels like
the openings in the filter.
After their paper - whose authors also included two
graduate students, Jun Yang and Fuzhi Lu - appeared in the
November issue of The Journal of Micromechanics and
Microengineering, Dr. Kostiuk became aware that the concept
of using water and tiny channels to create electricity had
been proposed in 1964 by J. Fletcher Osterle, a professor
of mechanical engineering at Carnegie Mellon University.
Dr. Osterle raised the idea in a paper that dealt mostly
with an effect that is the opposite of the one proposed by
the Alberta team: how, by applying electricity, the
electrokinetic effect could be used to make water flow.
While electrokinetic pumps that move liquids without any
moving parts are now in common use for testing drugs, the
study of electrokinetic generation seems to have all but
vanished.
Although Dr. Kostiuk cautions that much research remains to
be done, he suggested that electrokinetic generation on a
small scale might someday be used to power
micro-electro-mechanical systems, or MEMS, microscopic
machines that are fabricated by using silicon chip
technologies.
At the other extreme, he said it might be possible to
dribble huge quantities of water - perhaps at a treatment
plant - through an enormous porous surface to create
significant amounts of power. The low efficiency of the
current beaker generator, however, would have to be vastly
improved to make either use possible.
Ernest F. Hasselbrink Jr., an assistant professor of
mechanical engineering at the University of Michigan who
has long studied electrokinetic pumping, recently turned
his attention to using the effect for power generation.
While he thinks it has potential for powering small
objects, he said the extremely high efficiency of dynamos
will probably doom any efforts to create electrokinetic
power plants.
"I can't think of any situation where you have a large
amount of water and you can't install a turbine," Dr.
Hasselbrink said.
But Dr. Kostiuk said there was a good precedent for novel
forms of power generation that ultimately overcome initial
skepticism and shortcomings: solar panels. "Photovoltaics
were a curiosity with amazingly poor efficiency until the
U.S. space program needed them," he said.
January 1, 2004
By IAN AUSTEN
N.Y. Times
MOST people are familiar with how water can be used to make
electricity. Allow it to flow downhill past the blades of a
turbine, turning them as it rushes by. Attach the turbine
to a generator, and power is generated - hydroelectric
power, the kind produced by the megawatt at dams around the
world.
But there is another, far less familiar way of generating
electricity from the movement of water. Dripping it through
microscopic channels - the kind found by the hundreds of
thousands in a standard ceramic laboratory filter, say -
creates a buildup of positive and negative charges. Tap
into these charges with electrodes, and current will flow.
Researchers at the University of Alberta in Canada have
made such an electrical generator, inserting a filter into
the bottom of a beaker, attaching two coils of wire to the
filter to serve as electrodes, and filling the beaker with
water.
Unfortunately, the amount of electricity produced by this
"electrokinetic" method is extremely small - it won't do
much more than nudge the needle of an extremely sensitive
voltage meter. But the researchers say the method holds
promise and may someday be used to power small electronic
devices. If the materials can be successfully scaled up to
giant proportions, they say, it might even be used to build
power plants free of both pollution and moving parts.
Larry W. Kostiuk, a professor of mechanical engineering at
the university and the co-author of a recent paper on the
water generator, said the process would never overtake
conventional ways of making electricity, including
electrochemical batteries. But he added, "We find it
exciting that we have revived an area of science that's
been forgotten."
Edmonton, site of the University of Alberta campus, is
better known for its links to the oil and gas industry than
for research on alternative sources of energy. Until
recently Dr. Kostiuk's research in his department was
devoted to studying flares used at oil wells to burn
surplus gases.
But after Dr. Kostiuk agreed during a sabbatical to become
the chairman of the mechanical engineering department, he
realized that he had one shortcoming for his new post. "I
was a bit of a lab rat," he said. "I wasn't the most social
of people. So when I came back I thought I had to find out
what everybody was doing in the department."
Dr. Kostiuk began stopping by the offices of other faculty
members, asking them to explain their work. A particularly
long session unfolded with Daniel Y. Kwok, an assistant
professor who studies the interaction between materials at
the molecular level as part of his research into
nanotechnology. Like other researchers in that field, he
measures voltage changes caused by the interaction of
liquids with solids.
To Dr. Kwok, such measurements were mostly a way to study
the interactions, not experiments in generating
electricity. But Dr. Kostiuk was interested in the
electrical characteristics of the interaction.
"If you draw current, does it kill the whole system? Does
it start strong but drop off rapidly?" Dr. Kostiuk recalled
asking. "The more I asked Daniel these and other questions,
the more uncertain he was about what the voltage
characteristics would be."
In an effort to address those questions, Dr. Kwok had a
graduate student search through scientific papers. When the
student came up empty-handed, the filter-in-the-beaker
experiment was born. "It was a really, really bad
experiment," Dr. Kostiuk said. "I'm not sure the best way
to build electrodes is by just coiling up a few inches of
wire."
But the experiment did show that the water passing through
the pores generated a current. As has long been known, the
movement of water past a solid like the filter causes ions
on the filter's surface to become negatively charged, while
adjacent ions in the water are positively charged. The
experiment revealed that the tiny channels of the ceramic
filter - it had about 450,000 - align the ions to create a
negative end and a positive end, allowing a current to
flow.
Despite the crudeness of their materials (Dr. Kostiuk said
the filter used in the experiment was chosen only because
it was at hand), the researchers found that several factors
affected the electricity that emerged from their
no-moving-parts generator. In particular, the type of water
used made a significant difference.
Distilled water, which has relatively few ions, created
higher voltages but very little current in comparison with
Edmonton's tap water. Salt water made lower voltages but
higher current. Perhaps more important, the experiment
suggested that the easiest way to create more power is
simply to run more water through more microchannels like
the openings in the filter.
After their paper - whose authors also included two
graduate students, Jun Yang and Fuzhi Lu - appeared in the
November issue of The Journal of Micromechanics and
Microengineering, Dr. Kostiuk became aware that the concept
of using water and tiny channels to create electricity had
been proposed in 1964 by J. Fletcher Osterle, a professor
of mechanical engineering at Carnegie Mellon University.
Dr. Osterle raised the idea in a paper that dealt mostly
with an effect that is the opposite of the one proposed by
the Alberta team: how, by applying electricity, the
electrokinetic effect could be used to make water flow.
While electrokinetic pumps that move liquids without any
moving parts are now in common use for testing drugs, the
study of electrokinetic generation seems to have all but
vanished.
Although Dr. Kostiuk cautions that much research remains to
be done, he suggested that electrokinetic generation on a
small scale might someday be used to power
micro-electro-mechanical systems, or MEMS, microscopic
machines that are fabricated by using silicon chip
technologies.
At the other extreme, he said it might be possible to
dribble huge quantities of water - perhaps at a treatment
plant - through an enormous porous surface to create
significant amounts of power. The low efficiency of the
current beaker generator, however, would have to be vastly
improved to make either use possible.
Ernest F. Hasselbrink Jr., an assistant professor of
mechanical engineering at the University of Michigan who
has long studied electrokinetic pumping, recently turned
his attention to using the effect for power generation.
While he thinks it has potential for powering small
objects, he said the extremely high efficiency of dynamos
will probably doom any efforts to create electrokinetic
power plants.
"I can't think of any situation where you have a large
amount of water and you can't install a turbine," Dr.
Hasselbrink said.
But Dr. Kostiuk said there was a good precedent for novel
forms of power generation that ultimately overcome initial
skepticism and shortcomings: solar panels. "Photovoltaics
were a curiosity with amazingly poor efficiency until the
U.S. space program needed them," he said.