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Underwater Kite Harvests Energy From Slow Currents

A kite with a three-meter wingspan has just started to produce electricity in a pilot project off the coast of Northern Ireland.

The technology, dubbed Deep Green, consists of a wing with a gearless turbine mounted underneath that is tethered to the ocean floor. As the tide flows over the wing, it glides through the water and the turbine rotates. The tether also contains the unit's power and communication cables. For the pilot, there is an offshore control room in the inlet. The kites don't just float along anywhere they please—operators send them along a controlled trajectory to maximize energy output.

Deep Green can take advantage of lower velocity currents than most tidal technologies (less than 2.5 meters per second), according to Minesto, the company that makes the kites. Minesto hopes to field a 3-megawatt array in 2015.

The pilot involves a scaled-down version of Deep Green; the full-size versions have wingspans of between eight and fourteen meters. The eight-meter carbon fiber kite [PDF] has a rated power of 120 kilowatts at a tidal flow of 1.3 meters per second. The version with a 14-meter wingspan has a rated power of 850 kilowatts at 1.7 meters per second.

Although kite arrays could potentially be deployed in more locations than other tidal turbines, all tidal and wave technologies face considerable challenges, such as surviving in harsh, salty waters and being cost-competitive with other renewable energy options.

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Fukushima Operators Prepare to Remove Spent Fuel Rods

At Japan's crippled Fukushima Daiichi nuclear power plant, engineers are preparing to take the first big step toward decommissioning the facility. In the next few weeks, operators will begin removing the spent fuel rods from the storage pools in the badly damaged reactor 4. 

The Fukushima Daiichi plant was devastated in March 2011, when an earthquake and tsunami triggered a series of meltdowns and explosions at the plant. Reactor 4 was not in operation at the time of the accident; it was shut down for routine maintenance and refueling, which meant that its supply of fuel rods were in a storage pool on a top floor of the reactor building.

When an explosion shattered the reactor 4 building on 15 March, top nuclear officials in the United States and Japan worried that the pool had been structurally damaged, which would allow water to leak out and leave the fuel rods exposed and overheating. Since the spent fuel pools aren't sealed in heavy steel or concrete structures, such exposure would send large amount of radiation into the environment. The chairman of the US Nuclear Regulatory Commission, Gregory Jaczko, essentially caused an international incident when he stated on 16 March that reactor 4's spent fuel pool was empty of water. The public panicked until Japanese officials denied Jaczko's statements, and produced evidence that the pool was still full of water. 

The reactor 4 spent fuel pool continued to be a hot topic, however, with some activists questioning its structural integrity and its ability to withstand any future earthquakes. Additionally, its cache of 1533 fuel units—the most held at any of Fukushima's reactor buildings—makes it a priority for decommissioning.

TEPCO, the utility that owns the Fukushima Daiichi plant, has been preparing for this first fuel rod removal for some time. Workers have already removed much of the debris from inside the pool, and Japan's Nuclear Regulatory Authority has been inspecting the site and assessing the removal plan. When the operation begins in the next week or two, workers will use a crane to lift up the fuel assemblies and place them in submerged casks. Those casks will then be removed from the pool and taken elsewhere for safer storage. The video below, from TEPCO, explains the process in more detail. 

The operation is expected to be completed before the end of 2014. But that's just the first step in a decommissioning process that is expected to take 40 years. The spent fuel must be removed from the other reactor buildings before TEPCO can even being the process of locating and removing the active fuel in reactors 1, 2, and 3, all of which are thought to have suffered partial meltdowns.

Image: Tomohiro Ohsumi/AP Photo  

Global Energy Report Tracks Path From Doom to Slightly Less Doom

Solar power in the United States will shortly crack 10 gigawatts. Wind power has soared past 60 GW, and the vast potential of offshore wind is finally threatening to shift from potential to reality. Germany recently hit a record of 59.1 percent renewables on its grid. The punchline of all this good news? We have made essentially no real progress so far.

The International Energy Agency released its World Energy Outlook report for 2013 today, and it paints a picture of a world that is not changing its energy supply remotely fast enough to combat the various dangerous effects of climate change. The scariest tidbit is very simple to understand: the share of the world's energy mix attributed to fossil fuels has not changed at all in the last 25 years. Even with all those solar and wind power milestones adding up, it was 82 percent coal, oil, and gas in the late 1980s, just as it is right now.

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Nuclear Groundshift

Well, it's more like a subtle shifting or resettling of the ground after a slight tremor than like a full-fledged earthquake. But there are distinct signs indicating that educated and environmentalist opinion is moving in a distinctly more pro-nuclear direction.

One signal, noted here six months ago, occurred during a debate among the nine candidates vying at that time to be New York City’s next mayor. Invited to take a cheap, anti-nuclear shot by the moderator—who asked them whether they would favor closing the controversial Indian Point nuclear power plant north of the city—eight of the nine said they could not favor closing it unless ways were found to replace its electricity with clean, zero-carbon power. (One of those eight was the man just elected mayor by an overwhelming majority.)

Another sign of shifting opinion came last week, with the airing on Friday evening of a pro-nuclear documentary by CNN, the global cable news network. “Pandora’s Promise,” made by director Robert Stone, did not score high in television ratings. Still, it is noteworthy for the fact that CNN aired it and that Stone, who made an anti-nuclear film in 1988, has switched sides.

Some of Stone's reasons for changing sides, to be sure, are questionable. He minimizes the gravity of the nuclear accidents at Chernobyl and Fukushima, and he may overstate the degree to which newer or alternative reactor designs would be immune to catastrophe. He certainly overstates the promise and understates the drawbacks of the so-called Integral Fast Reactor, a kind of breeder that would allegedly be almost proliferation-proof and consume its own waste. (An ancestor of that reactor concept, the Experimental Breeder Reactor II, is shown in photo.) Physicist Edwin Lyman of the Union of Concerned Scientists has subjected Stone’s treatment of the IFR to a withering critique, which seems sound to me in every single detail.

But Stone also does a good job of conveying the promise of new reactor designs being developed, and of getting across the reminder that today’s reactors are basically just the first shot humankind took at harnessing the atom for peaceful purposes. He asks, quite reasonably in my opinion, why we get so exercised about the possible dangers of ionizing radiation and reactor accidents when millions of people are dying each year from exposure to air pollution from coal-fired power plants and automobiles.

Among other things, the film includes interviews with several leading environmentalists who have switched sides on nuclear, the most prominent of whom is probably Stewart Brand, creator of the Whole Earth Catalog.  Another such environmentalist, not included in Pandora’s Promise, is George Monbiot, a zoologist and immensely influential climate activist in Europe. Monbiot has recently posted a blog expressing his dismay that Helen Caldicott, the Australian physician who for decades has been a leading anti-nuclear activist, is saying many things about atomic power that cannot be substantiated in the scientific literature.

Some of us who have been following Caldicott’s activities for years are not exactly shocked to learn that she has made unverifiable assertions. But it is noteworthy nevertheless when a grassroots leader of Monbiot’s stature makes that discovery and publicizes it.

Photo: Argonne National Laboratory-West



What California's Energy Storage Requirement Really Means

A few weeks ago California passed the United States' first energy storage mandate. Issued by the California Public Utilities Commission (CPUC), the mandate commits all investor-owned utilities in the state to collectively buy what the mandate refers to as “1325 megawatts of energy storage” by 2020.

But as many Spectrum readers pointed out in the comments section of a recent Energywise post, energy storage is usually measured in units of energy, like joules or megawatt-hours, not units of power like megawatts. So what does it mean to ask utilities to prepare 1325 megawatts of energy storage?

Presenting the stipulations of the mandate in megawatts was "on purpose; it was deliberate," says  Haresh Kamath, a program manager at the Electric Power Research Institute (EPRI), in Palo Alto. "But there’s no question it was a little bit surprising that it was only megawatts and not megawatt-hours.” 

EPRI provided the CPUC with analysis and metrics on the cost efficacy of today's energy storage options. Kamath says that the issue was brought up repeatedly in the proceedings surrounding the mandate, but CPUC wanted the utilities to have maximum flexibility in how they implemented the storage systems.

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A Liquid Metal Battery for Grid Storage Nears Production

MIT spin-off Ambri is a step closer to bringing a novel liquid metal battery to the electricity grid.

The company on Thursday cut the ribbon on a new production facility in Marlboro, Mass., where it intends to make shipping-container size batteries. Ambri also said its first two customers will be a military base on Cape Cod, in Massachusetts, and a wind project in Hawaii. The company will be making prototypes and demonstration units in Marlboro for installation next year and intends to have a full-scale manufacturing facility in 2015.

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Good Vibrations Boost Solar Cell Performance

If you feel the energized by the sounds of your favorite band, you are not alone.

Solar cells, it turns out, could have the same reaction. Music vibrations boost the energy output of solar cells that contain nanorods. So says a new study from Queen Mary University of London and Imperial College London.

The high frequency of pop and rock music cause vibrations that increased the energy generation of solar cells with clusters of nanorods. Scientists had already known that straining zinc oxide materials could increase voltage outputs, but the effect had not been tested extensively on solar cell efficiency. Other scientists are looking to use other nano materials such as nanowires to boost the efficiency of solar cells

The British researchers grew billions of zinc oxide nanorods and coated them with an active polymer that could convert sunlight into electricity. They discovered that when the solar cells were exposed to sound, the photovoltaic efficiency increased by as much as 45 percent.

"We thought the sound waves, which produce random fluctuations, would cancel each other out and so didn't expect to see any significant overall effect on the power output," study co-leader James Durrant, professor of photochemistry at Imperial College London, said in a statement.

"The key for us was that not only that the random fluctuations from the sound didn't cancel each other out, but also that some frequencies of sound seemed really to amplify the solar cell output - so that the increase in power was a remarkably big effect considering how little sound energy we put in."

The researchers noted significant improvement in solar cell performance with levels as low as 75 decibels, a sound level similar to busy street traffic. They didn’t go as far as to compare the benefits of one band versus another, but did find that not all musical genres offered the same benefits. 

"We tried playing music instead of dull flat sounds, as this helped us explore the effect of different pitches. The biggest difference we found was when we played pop music rather than classical, which we now realize is because our acoustic solar cells respond best to the higher pitched sounds present in pop music," said Durrant.

Rather than streaming music to solar panels, the research would more likely be used to develop power sources for products that are already exposed to high-frequency acoustic vibrations, such as cars or air conditioners.


Image: iStockphoto

Pre-Paid Microsolar Coming to the Philippines

When Filipinos on the island of Alibijaban need to charge the car batteries they rely on for electricity, they take an eight-minute boat ride to the mainland to recharge the batteries at a local shop.

Alex Hornstein, an MIT-trained engineer, is looking to cut out the boat ride and a lot of the cost. Hornstein is piloting cellular-connected microsolar in Alibijaban, according to a report in Fast Company.

The project, Tiny Pipes, has installed 60-watt solar panels on the roof of about 20 homes in Alibijaban in conjunction with the local utility, Quezelco. The panels come with a connection to a cellular network that controls the power flow from the panel.

For houses with a panel, Tiny Pipes will own the panel and customers rent the panels and pay for the power they use through a cellphone payment. If customers don’t want unlimited charge for the battery, they can set up a prepaid plan for a set amount of energy daily or weekly.

In the United States, the falling price of solar panels and innovative financing methods, primarily solar leasing, have led to a solar boom. There are both similarities and differences in some of the projects being piloted in the developing world, which also rely on some innovative financing schemes and lower hardware costs. 

Generally speaking, remote villages pay a far higher percentage of their income towards power than developed or grid-connected regions. Fast Company reported that the residents of Alibijaban consume about one penny per day of electricity, yet they pay about US $1.50 to $2 per week to charge batteries.

In many poor regions, homes also rely on dirty kerosene lamps to provide light at night. Peru has a pilot to move 126 communities onto solar panels, with a goal of moving 500 000 rural households onto solar power. Other projects, such as SunBlazer, provide solar charging stations on wheels that are operating in some remote villages in Haiti.

Another group, SharedSolar, wants to go one step further and provide solar-powered microgrids that are connected to mobile payments so communities can not only have lights in homes but also power small businesses, such as selling ice. Some solar projects are looking to power other basic services, like clean water in India

Hornstein and his co-founder Shawn Frayne first wanted to make microsolar a reality in remote areas by lowering the cost and extending the lifespan of the hardware. They developed a small machine, Solar Pocket Factory, which makes microsolar photovoltaic panels that can power small electronics. They claim their panels have a 10-year lifespan, five times the life of traditional microsolar.

In their Kickstarter campaign, they also claim their panels can be produced locally for a lower cost than traditional microsolar because it is automated instead of made by hand. As they developed the Solar Pocket Factory, however, they realized that the circuitry they developed to connect the panel to mobile networks was ultimately a more significant breakthrough. Currently, there is not a panel maker that offers a wirelessly controlled panel from the factory.

Hornstein told Fast Company the panels have already withstood two typhoons and expects to expand to another 200 homes on Alibijaban and 1000 homes in another province next year.

“I want to be able to deploy Tiny Pipes at a scale that makes a dent,” said Hornstein in the article. “I'll start feeling like we're reaching that scale when we've hit a million installed panels.”


Photo: Alex Hornstein



Climate Monster Found Lurking in Ocean Depths

An article appearing in the November 1 issue of Science magazine analyzes mid-depth Pacific Ocean temperatures going back 10,000 years and finds a drastic increase in the amount of heat being absorbed and stored by ocean waters during the last 60 years. The study, by authors at Rutgers University, Columbia University's Lamont-Doherty Earth Observatory, and Woods Hole Oceanographic Insitution, reconstructs the history of temperatures in the western Pacific roughly 500-900 meters down through chemical analysis of shells from a species of single-celled organisms called foraminifers (or "forams").

The ratio of magnesium to calcium in the particular foram selected for study and found in ocean sediment cores, Hyalinea balthica, is a precise indicator of ambient temperature at the time the organism lived and died--a standard technique in paleoclimatology.

The three researchers found that the prevailing trend through most of the 10 000 year period was toward cooler temperatures. The cooling rate increased markedly during what's called the Little Ice Age of the European late Middle Ages, only to stop and reverse around the year 1600. After that the rate of Pacific warming was very gradual until about 60 years ago, when it leaped by a factor of 15. "Over a long time, the ocean's interior acts like a capacitor and builds up large (positive and negative) heat anomalies that reflect and, more importantly, affect the global climate," the article says.

There have been times in the ocean records that the three researchers compiled when water temperatures have been considerably higher than they are today, let it be said. The researchers emphasize the rate at which heat can be absorbed or ejected, and the big increase in the uptake rate during recent decades. “We may have underestimated the efficiency of the oceans as a storehouse for heat and energy,” commented Yair Rosenthal of Rutgers, the principal author of the study. “It [that heat storage] may buy us some time—how much time, I don't really know—to come to terms with climate change. But it's not going to stop climate change.”

The thinking is that storage of heat from a warming atmosphere represents a kind of lurking, growing monster that eventually will surface and return to the atmosphere.

Offshore Wind Farms Just Need a Little Stagger to Generate More Power

Neat rows of wind turbines dot seas and oceans across the world. But setting offshore wind turbines in straight lines may limit their power production, according to a new study.

Whether wind farms are on or off shore, there is a tradeoff between getting maximum energy from each individual turbine and packing a greater number of turbines into the space. As each turbine pulls energy from the wind, there is less energy in the downstream wind, which causes array losses for the entire wind farm. (Turbines not only affect their immediate neighbors, they can also affect other arrays miles away.) 

But there may be a simple solution to boost energy production without expanding the boundaries of offshore wind farms. Researchers at the University of Delaware found that staggering turbines in the ocean can improve annual power capacity by 13 to 33 percent. The study appeared in the September issue of Geophysical Research Letters.

“Staggering every other row was amazingly efficient,” Cristina Archer, associate professor of physical ocean science and engineering and geography in University of Delaware's College of Earth, Ocean, and Environment, said in a statement.

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