For all of humanity’s impressive innovations, sometimes, Mother
Nature really does know best. And as such, we’ve learned everything we
can from her, including this latest graphene solar cell breakthrough
inspired by none other than moth eyes. According to new reports,
researchers from the United Kingdom’s University of Surrey carefully
examined these insects’ eyes in order to create graphene sheets that
they say are “the most light-absorbent material ever created.” Best of
all, the graphene based cells won’t have to be outside in order to
harvest the sun’s energy — rather, it’ll be able to absorb indirect
sunlight as well as ambient energy from everyday items found at home. Related: Solar gadgets will make charging less frequent, not eliminate it forever
“We realized that the moth’s eye works in a particular way that traps
electromagnetic waves very efficiently,” Professor Ravi Silva, head of
the Advanced Technology Institute at the University of Surrey, told Newsweek.
“As a result of our studies, we’ve been able to mimic the surface of a
moth’s eye and create an amazingly thin, efficient, light-absorbent
material made of graphene.”
Speaking with Electronics Weekly,
Silva added, “Moths’ eyes have microscopic patterning that allows them
to see in the dimmest conditions. These work by channelling light
towards the middle of the eye, with the added benefit of eliminating
reflections, which would otherwise alert predators of their location. We
have used the same technique to make an amasingly thin, efficient,
light-absorbent material by patterning graphene in a similar fashion.”
The incredibly thin sheets of graphene are actually just one-atom
thick and are comprised of carbon atoms arranged in a honeycomb lattice.
But don’t let the delicate arrangement and rubber-like flexibility fool
you — the material is 200 times stronger than steel and is also more
conductive than copper. The hope is that graphene and these moth
eye-inspired sheets will be able to unlock new possibilities within the
Internet of Things, or power a host of different devices. As Newsweek
notes, everything from flexible smartphones to artificial retinas could
benefit from the new material.
“For many years people have been looking for graphene applications
that will make it into mainstream use,” said Silva. “We are finally now
getting to the point where these applications are going to happen. We
think that with this work that is coming out, we can see an application
very close because we’ve done something that was previously thought
impossible: optimizing its incredible optical properties.”
GE has a crazy new plan to harvest CO2 from the atmosphere and use it to store solar energy
http://www.digitaltrends.com/
By Lulu Chang
7 hours ago
If there’s one “resource”
the planet has too much of, it’s carbon dioxide. One of the primary
components to the greenhouse gases thought to be responsible for climate
change, CO2 has long been the bane of our environment’s health. But
now, GE thinks
it may have found a way to repurpose this gas into a useful energy
source — harvesting CO2 to actually create new solar batteries. It’s the
ultimate 180 on carbon dioxide’s harmful effects, and while scientists
have long captured and stored CO2 emissions, it’s been unclear as to how
best to utilize these massive reserves. That is, until now.
Effectively, GE hopes to use the CO2 as an enormous battery whose chief purpose would be to store solar energy.
Although the sun is a great source of energy, it’s rather undependable —
after all, the sun has to be out in order for us to capture its rays.
“That’s the grand challenge,” Stephen Sanborn, senior engineer at GE
Global Research said in a statement. “We need to make renewable energy
available to the grid when it is needed.”
And that’ll happen with the help of the significant CO2 reserves
scientists have been storing for ages. The process would work in two stages
— first, solar energy would be captured and kept in a liquid of molten
salt. Then, extra energy from the power grid would cool CO2 into dry
ice. When power is needed, the salt would turn the dry ice CO2 into what
is known as a “supercritical” fluid, which is matter that does not have
specific liquid or gas phases. The supercritical fluid would in turn
flow into a CO2 turbine called a sunrotor, whereupon energy would be
disseminated as needed. Related: Alaska Airlines delays flight so passengers can see solar eclipse at 37,000 feet
It sounds plenty complicated, but according to Sanborn, it’ll
actually be incredibly cost-effective. “It is so cheap because you are
not making the energy, you are taking the energy from the sun or the
turbine exhaust, storing it and transferring it,” he says. The scientist
claims that sunrotors could operate with 68 percent efficiency, which
is significantly better than today’s most effective gas power plants,
which are only 61 percent effective. “The result is a high-efficiency,
high-performance renewable energy system that will reduce the use of
fossil fuels for power generation,” Sanborn says.
We’re still around five to ten years away from seeing these babies in
action, but don’t despair, environmental activists — there is a way to
fight greenhouse gasses. And in a way, it’s with greenhouse gases
themselves.
If there’s one “resource” the planet has too
much of, it’s carbon dioxide. One of the primary components to the
greenhouse gases thought to be responsible for climate change, CO2 has
long been the bane of our environment’s health. But now, GE thinks
it may have found a way to repurpose this gas into a useful energy
source — harvesting CO2 to actually create new solar batteries. It’s the
ultimate 180 on carbon dioxide’s harmful effects, and while scientists
have long captured and stored CO2 emissions, it’s been unclear as to how
best to utilize these massive reserves. That is, until now.
Effectively, GE hopes to use the CO2 as an enormous battery whose chief purpose would be to store solar energy.
Although the sun is a great source of energy, it’s rather undependable —
after all, the sun has to be out in order for us to capture its rays.
“That’s the grand challenge,” Stephen Sanborn, senior engineer at GE
Global Research said in a statement. “We need to make renewable energy
available to the grid when it is needed.”
And
that’ll happen with the help of the significant CO2 reserves scientists
have been storing for ages. The process would work in two stages
— first, solar energy would be captured and kept in a liquid of molten
salt. Then, extra energy from the power grid would cool CO2 into dry
ice. When power is needed, the salt would turn the dry ice CO2 into what
is known as a “supercritical” fluid, which is matter that does not have
specific liquid or gas phases. The supercritical fluid would in turn
flow into a CO2 turbine called a sunrotor, whereupon energy would be
disseminated as needed.
It
sounds plenty complicated, but according to Sanborn, it’ll actually be
incredibly cost-effective. “It is so cheap because you are not making
the energy, you are taking the energy from the sun or the turbine
exhaust, storing it and transferring it,” he says. The scientist claims
that sunrotors could operate with 68 percent efficiency, which is
significantly better than today’s most effective gas power plants, which
are only 61 percent effective. “The result is a high-efficiency,
high-performance renewable energy system that will reduce the use of
fossil fuels for power generation,” Sanborn says.
We’re
still around five to ten years away from seeing these babies in action,
but don’t despair, environmental activists — there is a way to fight
greenhouse gasses. And in a way, it’s with greenhouse gases themselves
These Solar Farms Help—Not Harm—Birds and Bees
By Taylor Hill | Takepart.com
6 hours ago
TakePart.com
These Solar Farms Help—Not Harm—Birds and Bees
In the United Kingdom, threatened animals need all of the habitat they can get—even if it’s under solar panels.
That’s the idea behind a joint project by
conservation group Royal Society for the Protection of Birds and
alternative energy firm Anesco that aims to create and restore natural
habitats at solar farm sites in the U.K.
By planting wildflower
meadows and restoring natural grasslands in the “unused” margins between
solar panel rows, the team hopes to attract insects, bees, and
butterflies to the sites and provide food and nesting spots for birds.
It
could be a boon to the region’s threatened bird species, which have
seen marked declines in the last 40 years, with tree sparrow populations
dropping 93 percent, turtledoves declining 89 percent, and skylarks
falling 51 percent.
The U.K. has lost nearly 44 million breeding birds since the late 1960s, according to the British Trust for Ornithology’s The State of the UK's Birds 2014 report. And populations for 60 percent of all native species have declined over the last 50 years, the RSPB reported.
One reason is the continued loss of habitat because of agriculture and urbanization.
Solar farms—while providing emission-free renewable power—aren’t
known for protecting wildlife. Placing thousands of photovoltaic panels
in rows along the ground will inevitably affect wildlife, says
Stephanie Dashiell at the Nature Conservancy. RELATED: U.K. Renewables Beat Coal Power for the First Time Ever
But the size of the project and the amount of land clearing and grading is a big factor.
“For
smaller facilities [less than 50 megawatts], such as the facilities
that Anesco develops, this type of mitigation is a promising way to
minimize impacts to wildlife from the development of solar facilities,”
said Dashiell, who is an energy associate project director for the
conservancy in California. “However, the success of such measures
greatly depends on the size of the facility, the ability to install
panels without grading and fencing the land, and the ecosystem in which
the facility is being sited.”
Dashiell has researched the impacts
of large-scale photovoltaic facilities in California that have displaced
thousands of desert tortoises in the Mojave Desert and kit foxes and
giant kangaroo rats in the San Joaquin Valley. She said there haven’t
been any good examples of habitat restoration in California sites,
noting that solar companies often make up for wildlife impacts by
restoring habitat elsewhere.
Anesco operates more than 500
megawatts’ worth of ground-mounted solar panels across the U.K. and
Wales, meaning thousands of acres of habitat could soon be restored. In
the first phase of the project, RSPB experts are visiting solar farm
sites to help identify habitat restoration measures that would benefit
animals deemed to be under the most serious threat.
“Over the next
few years, we will be working with Anesco to further improve the
habitats created at their solar farm sites across the U.K.,” Darren
Moorcroft, RSPB’s head of species and habitats conservation, said in a
statement. “It is an excellent opportunity to develop habitats for
nature in need of our help, showcasing how a renewable energy business
and wildlife conservation can be delivered in unison.”
The
recommendations by RSPB’s research team will also be implemented in
Anesco’s biodiversity management plans for future solar farm sites.
“It’s
promising to see this type of collaboration occur for smaller-scale PV
projects in wetter ecosystems that can easily be restored,” Dashiell
said, adding that she hopes monitoring is done to compare the wildlife
differences between sites that are restored and those that are not.
In California, which has half of the United States’ entire solar capacity,
the arid landscapes aren’t as easy to restore once they’ve been
disturbed and would require water—a scarce resource in the region.
“Due
to the difference in ecological conditions, and the difference in the
scale of the solar PV projects in the U.K. versus California, the Nature
Conservancy continues to support an approach to solar energy
development that directs projects to locations that have the least
impact to wildlife, thus avoiding the greatest impacts to wildlife,”
Dashiell said.
http://www.takepart.com/
This European Country Is Set to Get Half Its Electricity From Renewables in 2016
Scotland is showing how other nations can ramp up carbon-free energy
without compromising the power grid.
Wind turbines at Whitelee Wind Farm in East Kilbride,
Scotland. (Photo: Jeff J. Mitchell/Getty Images)
Jan 28, 2016
Emily J. Gertz is an associate editor for environment and wildlife at TakePart.
Scotland
is poised to generate more than 50 percent of its electricity from wind
power and other renewable sources this year, according to a government
report released Thursday.
The report—Energy in Scotland 2016—confirmed
that the country generated 49.7 percent of its energy from onshore wind
and other renewable sources in 2014 and saw a 16 percent increase in
energy from those sources between January and September of 2015.
October to December figures were not included in the report. But the
trend suggests that Scotland has surpassed the government’s official
target of generating half its annual electricity consumption, or about
19 thousand gigawatt hours, from carbon-free sources by 2015—averting
the emission of more than 12 million tons of greenhouse gas pollution in
the process. Scotland’s
renewable energy production has surged since 2013—when renewables made
up 44.4 percent of the electricity supply—in parallel with three years
of sustained economic growth. Four of Europe’s 10 biggest land-based
wind farms are located in Scotland.
That puts the United Kingdom’s northernmost country among the top producers of renewable energy in the European Union. Norway
is powering its grid almost exclusively with hydropower and is a net
exporter of wind energy, while Austria and Sweden each generate more
than 60 percent of demand from renewables. Germany,
the world’s fourth-largest economy, produces about a third of its
annual electricity supply from wind, solar, and other renewables. Denmark last week announced that wind power supplied 42 percent of its electricity in 2015—a world record for wind.
“What we’re finding from countries like Scotland, Denmark, and
Germany is that you can have a high percentage of renewable generation
on your grid, and it won’t affect reliability,” said Scott Clausen, a
policy and research associate at the American Council on Renewable
Energy.
Scotland has pledged to generate the equivalent of 100 percent of its
electric power demand with renewables by 2020, and 30 percent of
overall energy demand, including transportation and heat.
Lang Banks, director of World Wildlife
Fund-Scotland, noted that Scotland’s renewable energy growth was at risk
of stalling in 2016 because policy shifts in London have created
uncertainty among investors.
U.K. Prime Minister David Cameron last year effectively canceled
government subsidies meant to encourage solar and wind power
investments. “The impact has been an unnerving of the industry,” Banks
said
“That’s not the way to reassure investors who are trying to invest
millions of pounds in renewable energy development,” he added. “You add
to that a government that is hell-bent on imposing nuclear power on the
U.K., and it’s like they’re looking two ways at the same time. They say
renewables are too expensive but are willing to use taxpayer money to
support even more expensive nuclear power.”
Clausen sees lessons for the United States in Scotland’s renewable
power progress, as well as a cautionary tale of how shifting government
policies might slow it down. The U.S. now gets about 17 percent of its
electricity from renewables. Wind, solar, geothermal, and other sources
generate about 10 percent, while hydropower supplies the rest.
“I think Scotland, even though they have crafted their goal in an
interesting way, sent a signal that got their market going,” Clausen
said. “It demonstrates the effectiveness that policy can play in
encouraging renewable energy development.”
Noting that in 2015 Congress extended two important tax credits for
green energy development, Clausen said the U.S. is poised for “very big
gains in renewable generation.”
Renewable power is growing faster than either natural gas or coal in
the U.S., with the federal Energy Information Agency forecasting a 9.5
percent increase in green energy in 2016.
With 29 states, Washington, D.C., and Puerto Rico enacting mandates
for renewable energy, the costs for both solar and wind power have
dropped sharply in the past five years, Clausen said. These “renewable
portfolio standards” require utilities to increase the percentage of
wind, solar, and other carbon-free sources of power by anywhere from 10
to 30 percent. California has set a target of 33 percent by 2020, and it aims to get half its electricity from renewables by 2030.
Efforts in state legislatures to roll back
renewable energy requirements, spearheaded by conservative groups such
as the American Legislative Exchange Council, have been largely
unsuccessful, although Nevada recently slashed incentives for solar energy.
But a big expansion of solar and wind energy in the U.S. would likely
pay for itself when taking into account the jobs and tax revenue
created by new power projects, as well as the public health benefits of
reducing air pollution and cutting the carbon dioxide emissions driving
climate change, Clausen said.
“We now get to make the low-cost argument,” he said. “You want to save money? You should build renewables.” This post has been revised to reflect the following correction: Correction 1/29/16: An earlier version of this
article misstated how much of Scotland's annual electricity demand is
likely to have been met by renewables in 2015. That amount is 19
thousand gigawatt hours.
Government-Backed Solar Plant Producing Only a Fraction of the Energy Promised
A solar power plant in California, built with a $1.6 billion
taxpayer-guaranteed loan, is in danger of being shut down entirely
because it is producing only a fraction of the energy that the owners
promised. The plant only generated 45 percent of expected power in 2014
and only 68 percent in 2015, according to government data.
What's
more, it is producing electricity at a cost of $200 per megawatt hour --
six times the cost of electricity produced by a natural gas-fired
plant. The Daily Caller:
These
disappointing results at high prices could be the solar plant’s
undoing. California Energy Commission regulators hoped the plant would
help the state get 33 percent of its electricity from green sources, but
now the plant could be shut down for not meeting its production
promises.Ivanpah — which is owned by BrightSource Energy, NRG
Energy and Google — uses more than 170,000 large mirrors, or heliostats,
to reflect sunlight towards water boilers set atop 450-foot towers that
create steam to turn giant turbines and generate electricity.
The
plant was financed by $1.6 billion in loan guarantees from the
Department of Energy in 2011. When the solar plant opened in 2014, it
was hailed as a great achievement by Energy Secretary Ernest Moniz.
“This
project speaks for itself,” Moniz said when the project went online in
early 2014. “Just look at the 170,000 shining heliostat mirrors and the
three towers that would dwarf the Statue of Liberty.”
“Ivanpah is
the largest solar thermal energy facility in the world with 392 MW of
capacity — meaning it can produce enough renewable electricity to power
nearly 100,000 homes,” Moniz said.
Moniz’s optimism aside, the
project faced huge problems from the beginning. NRG Energy asked the
federal government for a $539 million federal grant to help pay off the
$1.6 billion loan it got from the Energy Department.
NRG Energy
said the plant had only produced about one-quarter of its expected
output in the months after it opened. The company needed an infusion of
cash to help keep the project afloat.
That was only the beginning
of the company’s problems. Environmentalists quickly attacked the
project for killing thousands of birds since it opened. Many birds were
incinerated by the intense heat being reflected off Ivanpah’s
heliostats.
he Associated Press cited statistics presented by environmentalists in 2014 that “about a thousand… to 28,000” birds are incinerated by Ivanpah’s heliostats every year.
“Forensic
Lab staff observed a falcon or falcon-like bird with a plume of smoke
arising from the tail as it passed through the flux field,” according to
a U.S. Fish and Wildlife Service report from 2014.
“Immediately
after encountering the flux, the bird exhibited a controlled loss of
stability and altitude but was able to cross the perimeter fence before
landing,” FWS reported.
There's also the problem that pilots have when flying over or near the plant:
Pilots have also reported seeing a “nearly blinding” glare emanating from Ivanpah
while flying over the solar plant. The Sandia National Laboratory
reported in 2014 Ivanpah was “sufficient to cause significant ocular
impact (potential for after-image) up to a distance of ~6 miles.”
The
reason the owners requested the government-guaranteed loan is because
no investor in their right mind would take a flyer on what amounts to
gigantic experiment. A two billion dollar plant and it's not supposed to
make a profit -- just to demonstrate that solar power can be generated
at industrial levels.
But this turkey of a power plant can't even
do that. I don't mind solar power at all and I can't wait until it
becomes economically viable. The photovoltaic systems are improving in
efficiency all the time and the price is coming down.
But once
again, government is deciding who wins and who loses and it gave the
Democratic Party contributors at Google a taxpayer-guaranteed loan that,
at present, looks like is going to turn around and bite us in our
sustainable buttocks.
When it's time to construct a solar
mega-plant, investors will be beating down the doors looking to get in
on it. That's not happening now, nor is it likely to happen anytime soon
http://www.gizmag.com/
Invelox wind turbine claims 600% advantage in energy output
SheerWind's Invelox wind power generation unit is said to increase energy output by 600 percent.
SheerWind, a wind power company from Minnesota, USA,
has announced the results of tests it has carried out with its new
Invelox wind power generation technology. The company says that during
tests its turbine could generate six times more energy than the amount
produced by traditional turbines mounted on towers. Besides, the costs
of producing wind energy with Invelox are lower, delivering electricity
with prices that can compete with natural gas and hydropower.
Invelox takes a novel approach to wind power
generation as it doesn’t rely on high wind speeds. Instead, it captures
wind at any speed, even a breeze, from a portal located above ground.
The wind captured is then funneled through a duct where it will pick up
speed. The resulting kinetic energy will drive the generator on the
ground level. By bringing the airflow from the top of the tower, it’s
possible to generate more power with smaller turbine blades, SheerWind
says.
As to the sixfold output claim, as with many
new technologies promising a performance breakthrough, it needs to be
viewed with caution. SheerWind makes the claim based on its own
comparative tests, the precise methodology of which is not entirely
clear.
"We used the same turbine-generator (with a
given load bank) and mounted it on a tower as is the case for
traditional wind mills," SheerWind told Gizmag. "We measured wind speed
and power output. Then we placed the same turbine-generator system
(subjected to the same load), again we measured free stream wind speed,
wind speed inside the INVELOX, and power. Then we used the power-speed
relationship over 5 to 15 days (depending on the test), and calculated
energy in kWh. Six hundred percent more energy was for one of the days.
[...] The improvements in energy production ranged from 81 percent to
660 percent, with an average of about 314 percent more energy."
All else being equal, it would seem to be the latter category that is the most useful indicator.
Besides power performance and the fact it can
operate at wind speeds as low as 1 mph, SheerWind says Invelox costs
less than US$750 per kilowatt to install. It is also claimed that
operating costs are significantly reduced compared to traditional
turbine technology. Due to its reduced size, the system is supposedly
safer for birds and other wildlife, concerns that also informed the
designers of the Ewicon bladeless turbine. Finally, the system also makes it possible for multiple towers to network, that is, to get power from the same generator.
Utility-scale availability of Invelox is slated for 2014.
Solar Wind Energy's Downdraft Tower generates
its own wind
That is directed down the hollow tower and through turbines
placed around its base.
When we think of wind power, we generally think of
huge wind turbines sitting high atop towers where they can take
advantage of the higher wind speeds. But Maryland-based Solar Wind
Energy, Inc. is looking to turn wind power on its head with the Solar
Wind Downdraft Tower, which places turbines at the base of a tower and
generates its own wind to turn them.
Described by the company as the first hybrid
solar-wind renewable energy technology in the renewable energy market,
the tower at the center of the system generates a downdraft that drives
the wind turbines positioned around its base. This is done by using a
series of pumps to carry water to the top of a tower standing up to
2,250 ft (685 m) tall, where it is cast across the opening as a fine
mist. The mist then evaporates and is absorbed by hot, dry air, thereby
cooling the air and making it denser and heavier than the warmer air
outside the tower.
This water-cooled air then falls through the
hollow tower at speeds up to and in excess of 50 mph (80 km/h). When it
reaches the bottom of the tower, the air is directed into wind tunnels
that surround the base, turning wind turbines that are contained within
the tunnels. Although the system requires large amounts of water, the
bulk of the water emitted at the top of the tower is captured at the
bottom and recirculated through the system, being pumped back up to the
top with some of the power generated by the wind turbines.
In this way, the company claims the system
can generate electricity 24 hours a day, 365 days a year, when located
in a hot, dry area – although electricity generation would be reduced in
winter. Depending on the tower's geographical location, electricity
generation could also be supplemented through the use of vertical "wind
vanes" that would capture the prevailing wind and channel it into the
tower.
Solar Wind Energy says it has developed
proprietary software capable of determining a tower's electricity
generation capabilities based on the climate in geographic regions
around the globe. Using the software, the company says it can predict
the daily energy outputs of a tower based on its location and size.
Based on the most recent design
specifications, the company says a tower designed for a site near San
Luis, Arizona, would have a peak production capacity on an hourly basis
of up to 1,250 MWh on sunny days. However, when taking into account the
lower generation capabilities during the winter months, the average
hourly output per day comes out to approximately 435 MWh.
The company points out that once built (using
conventional materials, equipment and techniques), its towers are
capable of operating throughout the year independent of wind speeds with
virtually no carbon footprint, fuel consumption or waste generation.
Earlier this year, Solar Wind Energy gained
the necessary local entitlements to pursue development of its first
tower near San Luis, Arizona. The project got a leg up earlier this week
when it announced a financing agreement with JDF Capital Inc., which
will provide up to US$1,585,000 to the company. Solar Wind Energy says
it is also exploring potential sites in Mexico, which along with the
Middle East, Chile and India, would be an ideal location for the
technology in terms of climate.
The video below explains how the Downdraft Tower works.
Source: Solar Wind Energy Inc.
http://www.csmonitor.com/
Recycling sunlight: a solar cell revolution?
Scientists have found a way to recycle sunlight and boost the amount of energy captured from the sun's rays.
Criss Hohmann/Courtesy of St John's College, University of Cambridge
View Caption
The world of solar cells could be on the cusp of a revolution, as
researchers seek to boost efficiency by harnessing the power to recycle
light.
A new study, published Thursday in the journal Science, considers the properties of hybrid lead halide perovskites,
a group of materials already making waves in solar cell technology, and
demonstrates their ability to absorb energy from the sun, create
electric charge, and then churn out some light energy of their own.
Moreover,
the researchers demonstrated that such these cells can be produced
cheaply, with easily synthesized materials, making the proposition much
more commercially viable.
“We already knew that these materials were good at
absorbing light and producing charge-carriers,” says co-author Felix
Deschler of Cambridge University, UK, in a telephone interview with The
Christian Science Monitor. “But now we have demonstrated that they can
also recombine to produce photons again.”
Solar cells work by absorbing the light
energy – photons – from the sun, converting this energy into electrical
charge, and then conveying that charge to electrodes, which take the
energy out into the power-hungry world.
Hybrid lead halide
perovskites were already known to do this task efficiently, but what Dr.
Deschler and his team have demonstrated is an ability to do more: the
perovskites are actually able to emit light themselves after creating
charge – and then reabsorb that light energy.
The result is a
solar cell that acts like a concentrator, able to produce more energy –
to boost the voltage obtained from a given amount of light – than would a
cell made of materials without this recycling ability.
“Why this
is now a big thing is because the current record of photo cell
efficiency rests at 20-21 percent, whereas the absolute limit is 33
percent,” says Deschler. “Our results suggest a route to achieve that
limit.”
The efficiency of a solar cell refers to the percentage of energy, given a certain amount of light, it can harness for use.
According to a widely accepted 1961 paper
by William Shockley and Hans Queisser, theoretical thermodynamics cap
solar efficiency at 33 percent. It is simply impossible to do better,
they argued.
Yet the beauty of this most recent work is not only
the hope of climbing closer to that theoretical ceiling, but the
materials used to do so.
“You wouldn’t expect photon recycling in
our materials because their fabrication is so much simpler than others,”
explains Deschler. “Our materials are very cheap to make, very
versatile.”
The reason for surprise, even skepticism, is founded
in the way these materials are made – via solution. This affords little
control over the way in which the structure forms.
If you have
impurities in a crystalline structure, you are left with a “defect
site”, which makes the material “messier,” in terms of light absorption.
Without such impurities, you have what is known as a “sharp absorption
onset,” allowing efficient and clear absorption of the light.
“So,
while they are very efficient,” says Deschler, “we’re still trying to
understand why and how they’re better than other materials.”
The
researchers expect considerable interest from solar cell producers
looking for a cheaper, more efficient way to harness the power of the
sun.
http://www.computerworld.com/
New solar towers, cubes offer 20X more power, researchers say
Two small-scale versions of
three-dimensional photovoltaic arrays were among those tested by on an
MIT rooftop to measure their actual electrical output throughout the
day.
Credit:
Allegra Boverman
Researchers at MIT have discovered a method of optimizing solar energy collection by arranging photovoltaic (PV) panels on a tower or in a cube shape.
The new forms of solar energy collection offer anywhere from double to
20 times as much output compared with today's common flat-panels using
the same area.
The technology would be most advantageous in northern climates --
further away from the equator -- where the less intensive solar exposure
can be optimized.
MIT's research, the findings for which are based on both computer modeling and outdoor testing of real modules, were published in the journal Energy and Environmental Science.
"I think this concept could become an important part of the future of
photovoltaics," Jeffrey Grossman, an associate professor of Power
Engineering at MIT and lead author of the research paper, said in a
statement.
The cost of the 3D solar towers or cubes exceeds that of ordinary flat
panels. But the expense is partially balanced by a much higher energy
output for a given footprint, as well as much more uniform power output
over the course of a day and over the seasons when panels face less
light and more cloud cover, the researchers stated.
Allegra Boverman MIT's solar towers.
Because solar cells have become less expensive than accompanying support
structures, wiring and installation, the time is right to move forward
with the innovation, the researchers said.
Solar power generation is leading the cost decline in solar systems.
Solar photovoltaic (PV) module costs have fallen 75% since the end of
2009 and the cost of electricity from utility-scale solar PV has fallen
50% since 2010, according to a report from the International Renewable Energy Agency (IRENA).
In a separate report
issued by Deutsche Bank last year, the cost to generate power through
solar means was predicted to drop by 40% over the next three to four
years. Deutsche Bank has also reported that the cost of rooftop solar
power is expected to beat coal and oil-fired plant energy costs in just
two years.
MIT's 3D solar structures' vertical surfaces can collect much more
sunlight during mornings, evenings and winters, when the sun is closer
to the horizon, according to co-author Marco Bernardi, a graduate
student in MIT's Department of Materials Science and Engineering (DMSE).
The 3D solar structure improvements simply make power output more
predictable and uniform, which could make integration with the power
grid easier than with conventional systems, the authors said.
"Even 10 years ago, this idea wouldn't have been economically justified
because the modules cost so much," Grossman said. "The cost for silicon
cells is a fraction of the total cost, a trend that will continue
downward in the near future."
Can Dean Kamen make the Stirling engine part of our energy future?
As New Hampshire contemplates its energy future, maybe we should include a bit of energy past that has never quite succeeded.
That’s the idea behind an intriguing
proposal from Dean Kamen’s research firm, DEKA. It wants to power a
state-owned building with a Stirling engine, a design that has shown
great promise for more than a century but hasn’t been truly
commercialized.
If the proposal is accepted by lawmakers
and if it works, it might save the state a little money on electricity,
might help DEKA turn one of Kamen’s dreams into a real business, and
would go a long way toward burnishing New Hampshire’s credentials as a
place where interesting technology comes to life.
So how likely is it? It’s hard to say,
but since this is Granite Geek, we’ll contemplate the tech stuff before
we get to the lawmaker stuff.
A Stirling engine (named after Robert
Stirling, a Scottish minister who developed one of the prototypes 200
years ago) has two major differences from my car engine.
One is that it uses an external heat
source to create energy and move parts around rather than an internal
heat source created by a spark plug igniting a mix of gasoline and air.
The other is that it is a closed-cycle engine; the internal fluids and
gases stay inside, unlike the exhaust that is released by my car.
In theory, these make the Stirling
engine more efficient, less polluting and more flexible than
internal-combustion engines, since it can use any external heat source.
In reality, issues of heat transfer through materials, sealing fluids
and other engineering problems have kept it from working efficiently on a
useful scale except in a few limited applications.
Enter Kamen, famous for the Segway but
more importantly an inventor of medical devices, a major force in the
rebirth of Manchester’s millyard tech scene and the creator of the FIRST
Robotics Competition. Kamen has long been fascinated with Stirling
engines, creating them in various sizes and configurations to power
various devices. But they haven’t really worked out – until now, maybe.
“We have done a lot of work at DEKA to
make (the Stirling engine) a more viable, a more practical technology,”
said Jim Scott, a DEKA representative.
DEKA has built refrigerator-sized
Stirling engines, powered by natural gas, that it says can generate 10
kilowatts of electricity and 40 kilowatts of heat. (I didn’t even know
you could measure heat in kilowatts; energy units sure are confusing.)
A couple of these units have been helping
power DEKA’s millyard building at 100 Commercial St. since late 2013 as
part of a test, and the company has several more operating in other
buildings hither and yon. It says they are living up to their promise,
and now DEKA would like to put one in a state building in Concord to
give the project a much higher profile.
A law (Senate Bill 489) has been proposed
to allow the project to go ahead, at no cost to the state. “It’s like
hooking up a generator and a water heater, that’s all,” Scott said.
Scott showed up at a legislative hearing
last Tuesday to answer questions on the proposal, but as it turns out,
there weren’t any questions for him. Lawmakers on the Science,
Technology and Energy Committee mostly talked about whether the issue
should be handled by the Legislature or handled through the Executive
Council, which is usually the body that accepts gifts to the state
government. They’ll discuss the issue again Thursday.
Sen. Jeb Bradley of Wolfeboro, the prime
sponsor, argued that the bill had the potential to give a boost to a
well-known state company, above and beyond its energy benefits. “We have
nothing to lose by doing this,” he said.
Committee member Herbert Vadney, a state
representative from Meredith who is a mechanical engineer, said his
familiarity with Stirling engines made him less than optimistic. “I see
no reason for the state to get involved in an R&D project at this
point – this is a gift to somebody,” he said.
David Murotake of Nashua, another
committee representative with tech background, was more
supportive. “It might build New Hampshire as a skill center for Sterling
engines,” he mused.
Meredith Hatfield, director of the Office
of Energy and Planning, said she was interested in the project as the
state ponders ways to deal with the fast-changing energy universe, where
utilities and power production is being reinvented on the fly.
“We need to be looking at different ways
of doing things,” she told the committee. A natural gas-fired
electricity-producing engine might not be as cutting edge as fuel cells
or solar panels, but adding small-scale power plants could give the
state more flexibility to cope with changes coming down the pike.
Plus, she noted, DEKA’s offer is a
full-scale pilot project for free. “We don’t have the budget to test it
out ourselves,” she said dryly.
(David Brooks can be reached at 369-3313, dbrooks@cmonitor.com or on Twitter @GraniteGeek.)
The SOFC system after being installed at the Navy
Engineering and Expeditionary Warfare Center in Port Hueneme, Calif.
Credit:
U.S. Navy Photo by Michael Ard /released
The fuel cell only needs sunshine and seawater to produce thousands of watts of electricity
Boeing has announced
that, after 16 months of development, it has delivered a "reversible"
fuel cell for the U.S. Navy that stores energy from renewable sources
and generates zero-emissions electricity.
The Solid Oxide Fuel
Cell (SOFC) system, which can generate 50 kilowatts (KW) of power, is
the largest of its kind and can use electricity from wind or solar power
to generate hydrogen gas, which it then compresses and stores. U.S. Navy Photo by Michael Ard /released
The SOFC system after being installed at the Navy Engineering and Expeditionary Warfare Center in Port Hueneme, Calif. When power is required, the system operates as a solid oxide fuel cell, consuming the stored hydrogen to produce electricity.
The
SOFC system can scale to provide up to 400KW of power. It is being
tested as part of a micro power grid at the Navy's Engineering and
Expeditionary Warfare Center (EXWC) at Port Hueneme, Calif., .
"This
fuel cell solution is an exciting new technology providing our
customers with a flexible, affordable and environmentally progressive
option for energy storage and power generation," Lance Towers, director
of Boeing's Advanced Technology Programs, said in a statement. Creative Commons Lic.
How a solid oxide fuel cell works. A fuel cell is a device that uses stored chemical energy (in
this case, hydrogen) and converts it into electricity. The SOFC device
uses solar power to strip seawater of its hydrogen molecules through electrolysis.
The hydrogen gas can then be stored and later used in the fuel cell
stack where it electrochemically reacts with oxygen in ambient air to
produce electric current, heat and water.
Omar Saadeh, a senior
grid analyst at GTM Research, said the military is an enormous energy
consumer with a high demand for reliability with regard to mission
critical systems; so it only makes sense that they'd invest in a
combination of on-site power generation and microgrid technologies.
"At
forward operating bases, for example, deploying renewables not only
enhances energy efficiency, but more importantly, also reduces the
logistical risk in transporting fuel over distant and often hostile
territory," Saadah said in an email reply to Computerworld.
Microgrids
are small-scale power infrastructures that operate autonomous from the
centralized grid run by utilities. According to a 2015 microgrid study
by GTM Research, the military made up 35% of U.S. operational microgrid
capacity.
While solar power is often promoted as the resource of
the future, natural gas-fired generation accounts for 67% of the
military’s domestic microgrid energy generation, Saadah said.
"This
is due to its rapid dispatchability and reliability as a larger-scale
power source," he said. "That being said, remote bases, which are
smaller by nature, are deploying renewable and storage combinations as
economically viable solutions that to meet today’s energy needs."
The SOFC manufacturers include Boeing in Huntington Beach, Calif. and Sunfire in Dresden, Germany.
The
technology is unique in being able to both store energy and produce
electricity in a single system, making the technology "reversible,"
Boeing said.
"The SOFC is a most promising technology for both
remote islands and expeditionary applications," Michael Cruz, EXWC
project manager, said in a published report.
"Combined with a solar photovoltaic array, a SOFC system generates
electricity, potable water, and heat with only two inputs, sunshine and
seawater."
Given how fantastically cheap silicon-based photovoltaic cells have
gotten, it might be hard to muster much excitement for developing any
other material. But the cost of silicon-based PV has created a potential
niche—it's so cheap that installation costs now dominate the price of
solar power. If we could squeeze more energy out of a single
installation, it could drop the costs even further.
That's one of the reasons researchers have been trying to develop
perovskites. Not only are these made from chemicals that are cheap and
easy to manufacture, there are indications that they can be tuned to
absorb some wavelengths while allowing others to pass through to an
underlying silicon photovoltaic. The big problem: they tend to decompose
when exposed to intense light.
Now, an Oxford-Berlin collaboration is reporting they may have solved
the decomposition problem and, in the process, accidentally made a
material where they could tune the absorbance across a wide range of
wavelengths. With some additional improvements, they suggest a combined
silicon-perovskite cell could reach 30 percent efficiencies—up from the
neighborhood of 22 for silicon alone.
Perovskites aren't actually a single material; instead, they're a
variety of chemicals that all form a similar crystal structure. For
photovoltaics, they're often a mix of lead, bromine or iodine, and a
small nitrogen-containing organic molecule. None of these is very
expensive, and it's relatively easy to form a layer of perovskite
materials using bulk techniques. The best of these materials has
photovoltaic efficiencies in the teens. That's lower than silicon, but
expectations are that it can be brought up even higher.
But the new paper doesn't focus on stand-alone perovskites; its
authors are interested in combining them with silicon photovoltaics. For
that to work, the bandgap of the perovskite and that of the silicon
have to be distinct so that they absorb photons at different
wavelengths. Since a variety of chemicals can form a perovskite-like
structure, then simply finding the right combination should allow us to
tune the perovskite so that it works with silicon.
The researchers began with a pretty standard perovskite starting
material: a mixture of lead, iodine, bromine, and the organic molecule
HC(NH2)2. This material had been tested before but
found to suffer a problem typical of other perovskites—they break down
when exposed to light and/or high temperatures. In this case, the
material is unstable at temperatures above 85 degrees Celsius, which
causes internal rearrangements to the crystal structure that eliminate
its perovskite-ness.
The authors began by substituting some cesium for a portion of
organic molecule, figuring it could push the temperature limit a bit
higher. Instead, nearly every combination they tested was largely
stable, although they only tested exposure to light for about an hour
(something that needs significant follow-up). The team was also able to
vary the bromine and iodine composition at the same time.
By tweaking these two chemical ratios (Cs to HC(NH2)2
and I to Br), they were able to fine tune the band gap of the material.
To work well with silicon, they were targeting a bandgap of 1.75
electronVolts; they were able to make perovskites with a 1.74eV bandgap.
"We have total flexibility and predictability in tuning the composition
and its impact on the band gap," the researchers conclude.
On their own, these films exhibited a photovoltaic efficiency of
nearly 15 percent—pretty good for a perovskite. When placed in front of
silicon PV hardware, the silicon's efficiency dropped from 19 percent to
a bit over seven percent. That's a pretty big drop, and it suggests
that a two-layer design of this sort would only reach about a 20 percent
efficiency, which is not much better than the silicon on its own.
However, the authors suggest that it would be relatively easy to
reduce the opacity of the perovskite and design its cells to more
actively manage the light passing through them. Different silicon cells
could potentially boost the efficiency even more. The end result, they
suggest, is that a 30-percent efficient two-layer cell could be
attainable.
Right now, we already have cells with these sorts of efficiencies;
they're just too expensive for widespread deployment. But if a
perovskite layer could be added at a relatively low cost, it could shift
the economics of installing photovoltaic hardware. The panels would be a
bit more expensive, but they would produce a lot more electricity for
the same installment costs. Science, 2015. DOI: 10.1126/science.aad5845 (About DOIs).
Most people think of batteries when they consider energy storage, but
capacitors are an alternative in some use cases. Capacitors are used in
almost all electronic devices, often to supply temporary power when
batteries are being changed to prevent loss of information. In addition
to everyday devices, they are also used in more obscure technologies,
including certain types of weapons.
Understanding the supercapacitor
Unlike batteries, capacitors use static electricity to store energy.
In their simplest form, they contain two conducting metallic plates with
an insulating material (dielectric) placed in between. A typical
capacitor charges instantly but usually cannot hold a great deal of
charge.
Supercapacitors can at least partly overcome this
shortcoming. They differ from the typical capacitor in that their
"plates" provide significantly larger surface area and are much closer
together. The surface area is increased by coating the metal plates with
a porous substance. Instead of having a dielectric material between
them, the plates of a supercapacitor are soaked in an electrolyte and
separated by an extremely thin insulator.
Carbon supercapacitors offer high electrical power, low weight, and
fast charge-discharge cycles. But it's difficult to get carbon to
provide a high enough surface area to bring the energy density up to
where it could compete directly with batteries.
Though some carbon materials have been made to exhibit a high
supercapacitance in theory, they are not able to translate those gains
into real-world applications. For example, graphene supercapacitors
exhibit a theoretical capacitance of 550 F/g but only reach 300 F/g when
used in real-life applications.
Improving one atom at a time
Recently, scientists have focused on altering the surface of
carbon-based supercapacitors to increase their potential to store
charge. In this case, the supercapacitor system under investigation is
composed of carbon plates that contain nano-sized pores (mesoporous
carbon) with a polymer insulator. They have altered the surface of the
mesoporous carbon plates by the addition of nitrogen. Doping in nitrogen
has allowed for reactions between the nitrogen and carbon.
These "redox" reactions result in the movement of electrons from one
species to another.
In this study, the scientists demonstrated the ability to produce an
electrochemically active substance from layered carbon (similar to
graphene) by nitrogen doping.
In order to make the material, they used a sacrificial porous silica
template containing self-assembled tubes. This material was then covered
with a thin layer of carbon. The silica was then etched away, leaving a
self-supported ordered superstructure, with a thickness of only a few
atomic layers of carbon.
Since this process was rather involved, they also demonstrated a
simplified, template-free method to produce a similar carbon
structure with the same overall performance.
These materials were imaged and found to have nanometer-sized tubes
that are evenly spaced throughout the material. The tubes themselves
were found to be composed of graphene-like sheets with fewer than five
total layers. After nitrogen doping, these structural features still
remained, but the surface area increased dramatically, as did the total
pore volume. The higher surface area should allow it to store more
charges.
Performance doping with nitrogen
The scientists tested the capacitance of the nitrogen-doped structure
using an aqueous electrolyte. The system was found to have a
capacitance of 855 F/g—quite a big step above the graphene-based
materials. They also found that the system can be charged and discharged
very quickly.
The unusually high capacitance exhibited by this system can be
attributed to robust redox reactions. In the course of these reactions,
the nitrogen reacts with the carbon on the surface of the plates,
forming a variety of compounds. As a result, the layered carbon material
is transformed into an electrochemically active substance while
maintaining its electrical conductivity. Nitrogen doping also altered
other physical properties that are conducive to supercapacitive
performance, including resistance, hydrophobicity, and electrostatic
charge.
After nitrogen doping, these carbon-based systems can store 41
watt-hours per kilogram. Though that's still not enough to compete with
batteries in their energy-storage capabilities, this approach
demonstrates that significant improvements in supercapacitor energy
storage are still possible. Science, 2015. DOI: 10.1126/science.aab3798 (About DOIs).
The first comprehensive study of the planet's groundwater
revealed not only how much of Earth’s water lies beneath its surface,
but also how old it is.
The study, published Tuesday by the journal Nature Science, followed up on a hasty estimate of the planet's water supply that had not been updated since the 1970s, according to a press release.
The
water beneath the Earth's surface would - if somehow spread
horizontally in something resembling an epic remake of "The Ten
Commandments" - cover the continents with 600 feet of water. That is a volume of 6 quintillion gallons, wrote Deborah Netburn for the Los Angeles Times.
"This has never been known before," said lead author Tom Gleeson from the University of Victoria in a press release.
Most of this water, it turns out, is quite
old. Researchers gathered data on which bodies of water had trickled
underground less than 50 years ago. They were interested in studying how
quickly water is traveling back up to the surface and into the regular
water cycle, as well as determining if “newer” water contained acids or
pollutants from surface industrialization.
The vast majority –
94.4 percent – of underground water has been there for more than 50
years, meaning only about 5 percent of the planet’s underground reservoir has seen the sun
recently, George Dvorsky wrote for Gizmodo. The fresh, young water
closer to the surface is purer and much easier for humans and other life
to use, but the older water deeper down can be saltier than ocean water
and sometimes contains arsenic and uranium.
Humid land areas such
as the Amazon, the Congo, Indonesia, and the Rocky Mountains had high
levels of groundwater. The Sahara Desert and the Australian Outback did
not.
"Intuitively, we expect drier areas to have less young
groundwater and more humid areas to have more, but before this study,
all we had was intuition," said co-author Kevin Befus, who studied
groundwater for his doctoral thesis at the University of Texas at
Austin, in a press release. "Now, we have a quantitative estimate that
we compared to geochemical observations."
A map shows
concentrations of groundwater on all the continents except the
northernmost and southernmost land masses, for which there is no data,
but the permafrost in these areas likely contains little groundwater,
according to Gizmodo.
Researchers used multiple datasets,
40,000 groundwater models, and data from more than a million
watersheds, according to a press release. They found 23 million cubic
kilometers of underground water.
