Proponents of clean energy will soon have a new source to add to their existing array of solar, wind, and hydropower: osmotic power. Or more specifically, energy generated by a natural phenomenon occurring when fresh water comes into contact with seawater through a membrane.
Researchers at EPFL's Laboratory of
Nanoscale Biology have developed an osmotic power generation system that
delivers never-before-seen yields. Their innovation lies in a three atoms thick
membrane used to separate the two fluids. The results of their research have
been published in Nature.
The concept is fairly simple. A
semipermeable membrane separates two fluids with different salt concentrations.
Salt ions
travel through the membrane until the salt concentrations in the two fluids
reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater
and fresh water, salt ions in the seawater pass through the membrane into the
fresh water until both fluids have the same salt concentration. And since an
ion is simply an atom with an electrical charge, the movement of the salt ions
can be harnessed to generate electricity.
A 3 atoms thick, selective membrane
that does the job
EPFL's system consists of two
liquid-filled compartments separated by a thin membrane made of molybdenum
disulfide. The membrane has a tiny hole, or nanopore, through which seawater
ions pass into the fresh water until the two fluids' salt
concentrations are equal. As the ions pass through the nanopore, their
electrons are transferred to an electrode - which is what is used to generate
an electric current.
Thanks to its properties the
membrane allows positively-charged ions to pass through, while pushing away
most of the negatively-charged ones. That creates voltage between the two
liquids as one builds up a positive charge and the other a negative charge.
This voltage is what causes the current generated by the transfer of ions to
flow.
"We had to first fabricate and
then investigate the optimal size of the nanopore. If it's too big, negative
ions can pass through and the resulting voltage would be too low. If
it's too small, not enough ions can pass through and the current would be too
weak," said Jiandong Feng, lead author of the research.
What sets EPFL's system apart
is its membrane. In these types of systems, the current increases with a
thinner membrane. And EPFL's membrane is just a few atoms thick. The material
it is made of - molybdenum disulfide - is ideal for generating an osmotic
current. "This is the first time a two-dimensional material has been used
for this type of application," said Aleksandra Radenovic, head of the
laboratory of Nanoscale BiologyPowering 50'000 energy-saving light bulbs with 1m2 membrane
The potential of the new system is
huge. According to their calculations, a 1m² membrane with 30% of its surface
covered by nanopores should be able to produce 1MW of electricity - or enough
to power 50,000 standard energy-saving light bulbs. And since molybdenum
disulfide (MoS2) is easily found in nature or can be grown by
chemical vapor deposition, the system could feasibly be ramped up for
large-scale power generation. The major challenge in scaling-up this process is
finding out how to make relatively uniform pores.
Until now, researchers have worked
on a membrane with a single nanopore, in order to understand precisely what was
going on. '' From an engineering perspective, single nanopore system is ideal
to further our fundamental understanding of membrane-based
processes and provide useful information for industry-level
commercialization'', said Jiandong Feng.
The researchers were able to run a
nanotransistor from the current generated by a single nanopore and thus
demonstrated a self-powered nanosystem. Low-power single-layer MoS2 transistors
were fabricated in collaboration with Andreas Kis' team at at EPFL, while
molecular dynamics simulations were performed by collaborators at University of
Illinois at Urbana-Champaign
Harnessing the potential of
estuaries
EPFL's research is part of a growing
trend. For the past several years, scientists around the world have been
developing systems that leverage osmotic power to create electricity. Pilot
projects have sprung up in places such as Norway, the Netherlands, Japan, and
the United States to generate energy at estuaries, where rivers flow into the
sea. For now, the membranes used in most systems are organic and fragile, and
deliver low yields. Some systems use the movement of water, rather than ions,
to power turbines that in turn produce electricity.
Once the systems become more robust,
osmotic power could play a major role in the generation of renewable energy.
While solar panels require adequate sunlight and wind turbines adequate wind,
osmotic energy can be produced just about any time of day or night - provided
there's an estuary nearby.
Researchers
at EPFL's Laboratory of Nanoscale Biology have developed an osmotic
power generation system that delivers never-before-seen yields. Their
innovation lies in a three atoms thick membrane used to separate the two
fluids. The results of their research have been published in Nature.
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
Researchers at
EPFL's Laboratory of Nanoscale Biology have developed an osmotic power
generation system that delivers never-before-seen yields. Their
innovation lies in a three atoms thick membrane used to separate the two
fluids. The results of their research have been published in Nature.
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
Researchers
at EPFL's Laboratory of Nanoscale Biology have developed an osmotic
power generation system that delivers never-before-seen yields. Their
innovation lies in a three atoms thick membrane used to separate the two
fluids. The results of their research have been published in Nature.
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.
If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
Proponents of clean
energy will soon have a new source to add to their existing array of
solar, wind, and hydropower: osmotic power. Or more specifically, energy
generated by a natural phenomenon occurring when fresh water comes into
contact with seawater through a membrane.
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
Read more at: http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.html#jCp
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