In most cases, power storage systems are separate from power generation systems, and it doesn’t matter for storage whether the electricity was generated by wind or solar or some other technology. But molten salt is a different case. Molten salt is a method used for power collection in concentrating solar power systems, but its characteristics mean that it also acts as a storage medium that allows power to continue to be generated by a solar power facility even after the sun has set. Though less of a pure power storage solution than some of the other methods we have discussed in this series, it does allow a renewable power source to be operated in a much more constant fashion, and providing a steady and reliable supply of power to those who need it when they need it is the ultimate goal of all of these systems.

Molten salt absorbs solar energy as it is circulated through the collector troughs or through a focal point on a tower surrounded by a field of mirrors that concentrate the sun’s energy. Because of its high melting point, molten salt has a great deal of capacity to absorb and store heat before the material begins to vaporize.

By keeping the material in insulated storage tanks and maintaining a high temperature throughout the power cycle, molten salt systems do not rely on phase change of the heat transfer material (such as water being turned into steam in systems ranging from coal-burning to nuclear reactors to solar concentrating facilities), although the secondary heat transfer from the molten salt is still used to boil water and run the turbines that generate electricity. This also means that there is very little vapor pressure in the system, which makes it safer and easier to deal with circulating through the system. However, keeping the salt from freezing at night is one of the concerns that these systems have to deal with.

The molten salt is at such a high temperature (above 750 degrees F, or 400 degrees C) that it can readily transfer heat to boil water to generate electricity. And, with the extremely high temperatures that the salt reaches, it contains an incredibly large amount of energy which persists for hours or days within insulated storage tanks.

The salts being used currently in molten salt plants are a mixture of sodium and potassium nitrate. These materials are also widely used as fertilizers, so they are not particularly hazardous should there be a break in the system that causes a spill of the material.

Using high temperature molten salt systems also allows a concentrating solar power plant to operate for longer periods of time which makes it more able to be used as a base load power plant, rather than acting as an intermittent power plant whose production is unpredictable and varied. For power generation purposes, this reliability is important in balancing the needs of power consumers with the available power being generated.

The output of a photovoltaic panel can vary widely depending on whether it is being illuminated directly by the sun, or more diffuse and indirectly under cloudy conditions. But with the concentrating solar power system, variability is less of an issue because the temperature of the molten salt will remain very high even if a cloud passes across the sky for a short while. And even overcast conditions provide a great deal of solar energy which can be readily amplified by the concentrating mirrors in this type of facility.

In addition to the power storage benefits it provides, molten salt also makes a concentrating solar power plant more efficient by being able to absorb more energy than other transfer and collection materials. The oils used in some other facilities begin to break down as temperatures climb above a few hundred degrees, so the temperature of the material needs to be kept in check, and the full energy of the sun is not able to be captured. Molten salt operates at high temperature, and is able to withstand temperatures of over a thousand degrees without turning to vapor, so it can absorb and transfer more of the energy that can be collected. It is also more manageable throughout the power cycle because it does not produce high pressures withing the working medium as other materials do.

Pilot molten salt thermal solar plants have been tested and operated dating back to the 1990s. At present, a 110 megawatt solar thermal plant is under construction in Nevada and is expected to be completed late in 2013.

Main photo: Birds eye view of a molten salt reactor. Credit: Oak Ridge National Laboratory.

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Sprout’s parent company, E. Gluck Corp., has been in the watch business for more than 50 years. With that knowledge and experience, the company is able to ensure each timepiece is high quality as well as environmentally friendly.

“Every product, everything we buy, in some way harms the environment,” said Marcella Maselli, the creative mastermind of Sprout. “The idea is to cause as little harm as possible by using things like biopolymers and recycled and natural materials. Consumers love the idea that Sprout watches will not litter the Earth for thousands of years, nor do they use up valuable resources.”

Watches are not used entirely for their function, of course, so Sprout also uses several materials to make their timepieces more fashionable. Some models feature conflict-free diamonds or incorporate mother of pearl faces. While these materials make the watches slightly less environmentally friendly than, say, a full corn resin model, a striking appearance is incredibly important in the jewelry industry — especially when trying to sway certain consumers to purchase green products instead of conventional ones.

“First and foremost, all of the materials we choose to include in Sprout watches are in some way better than alternative or conventional materials in terms of harm to the environment or humans.  At the same time, we are a watch brand that offers a fashionable approach to eco-consciousness, and mother of pearl and diamonds are part of acknowledging trends while still being true to our brand mission. All of our Mother of Pearl is declared through the Department of Fish and Wildlife in the U.S. and will never be from forbidden or endangered species. Much the same, we source our diamonds from reputable dealers who certify that they are conflict-free.”

We received a black corn resin watch with a mother of pearl face and diamond accents. The corn resin band feels much like hard plastic, and though the material is biodegradable, it is not made to deteriorate during its life of use. The watch band came slightly too large, but simple instructions on the Sprout website — in order to save paper, the company does not include instructions in the box  — and a few minutes of work resulted in a better fit. If the band is too small for your wrist, extra links are also available by calling Sprout.

The mother of pearl and small diamonds add some color and flair to the piece. The diamond placement at hour marks also gives the watch a refreshing face by providing relief from a full circle of Arabic numerals.

Other watch components include a mercury-free battery, mineral crystal lens and a stainless steel butterfly clasp. All Sprout models feature mineral crystal lenses instead of traditional Plexiglas. The visible qualities of each material are equivalent, but the mineral lens is made from sand and is supposedly more durable (but that certainly doesn’t mean you should be rough on your watch — it’s not indestructible).

Interested in a different feel or look for your watch? The organic cotton models are colorful and some have cute designs, like the lime green owl model, which would be perfect for kids. Tyvek models have a leather-like appearance and the material is both water-resistant and recyclable. For leather fans, Sprout also has a line of fish leather watches, using leftover skins from Asian farmers who harvest fish for human consumption.

“The concept of the exotic fish leather was introduced to us at a seminar on sustainable materials in New York,” said Maselli. “The look and feel of the fish leathers are so luxurious and unexpected that we immediately fell in love with the idea of using them for our straps. We also loved that they were made from the by-product of the food industry and the idea of turning something that would otherwise be discarded as trash into something beautiful fit right in with the design spirit behind Sprout watches.”

Sprout also just introduced a line that uses teak and maple wood bezels.  The wood comes from leftover manufacturer pieces, making use of what would otherwise be thrown out.

Seeing all these interesting eco watches, we asked Maselli what to expect next from the company. “For future development, we are always on the lookout for new materials to add to the depth of the line,” she said. ” Currently, we are exploring the use of wool felt and hemp materials for our straps. We are also looking into sourcing handmade goods from indigenous tribes in Africa. The beauty of a line like this is that, if you look hard enough, the possibilities are endless.”

Disclaimer: Sprout provided Revmodo with a watch for review.

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Gravel batteries are one of the newest concepts for storing power. The concept is new enough that, at this point, there are not yet any facilities to demonstrate the process and prove its effectiveness. The term “gravel battery” itself is somewhat misleading. This form of power storage is much more akin to compressed air storage systems rather than it is to chemical batteries.

Fundamentally, the gravel battery system can be understood as a giant heat pump. The process uses a heat engine with pistons and valves rather than turbo systems to compress the gas in its system. This prevents a number of thermal losses that are otherwise present in other kinds of compression systems. The overall efficiency of the system is expected to be in the range of 70 – 80 percent, which is similar to that of pumped hydro.

Argon gas is compressed and then pumped into an insulated silo filled with “lightly processed (crushed, graded and cleaned) mineral particulate,” i.e. gravel. As the gas moves through the silo, it heats the gravel to over 900 degrees F (500 degrees C) while cooling the gas to ambient temperature. The gas is then passed through a second gravel-filled silo which returns it to normal pressure while cooling the second silo down to -256 degrees F (-160 degrees C). The process can be reversed in order to run a generator to supply electricity when additional power is needed.

Although the process is still theoretical, Isentropic, the company that has developed this technology, is developing a demonstration facility to prove that the process will work as expected. This pilot plant will have two storage tanks, each 7 meters (23 feet) tall and 7 meters in diameter, which will provide a storage capacity of 16 megawatt-hours. Although it is still very much an experimental system, if the technology proves to perform as expected, then it could provide a new and inexpensive method for storing power.

Gravel is a very inexpensive material, and it is readily available anywhere in the world. It also serves as a very effective thermal mass which can go through a wide range of temperatures without changing phase (unlike a fluid boiling at high temperature, for example) or breaking down. Because there is no reliance on refrigerants or on extremely complicated systems, gravel batteries offer the potential for inexpensive power storage that can be installed wherever it is needed.

The thermal capacity of the gravel battery means that it can store energy for long periods of time, as well. The designers say that, if left alone, a gravel battery would still retain half of its energy even after 3 years. This could be useful for dealing with seasonal supply variability from renewable sources or with demand fluctuations in power needed by the grid.

Gravel batteries can be installed in modular fashion, allowing for large-scale installations. One advantage that the company is promoting for gravel batteries is that, like several other of the industrialized power storage systems (including batteries, flywheels, and even some compressed air systems) they can be located anywhere. Compared to a pumped hydro storage system, Isentropic’s founder, Jonathan Howes, notes that a gravel battery facility with similar power storage capacity would require only 1/300th of the space.

As with pumped hydro storage, gravel batteries are probably not especially good for fast-response grid load balancing, and would likely be used to supplement base-load energy demand.

Main photo credit: Phlat Phield Photos; diagram credit: Isentropic

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Water is not the only material that can be stored and harnessed to be used for energy storage. Air can also be used as an energy storage medium with what is known as Compressed Air Energy Storage (CAES). Several different methods are being explored to use this type of energy storage, although the earliest examples have been in place for decades.

Using underground caves to store compressed air is a technology that dates back to the 1970s in Huntorf, Germany, where a 290 megawatt facility was built using a salt dome. A similar, though smaller (110 megawatt) facility was built in Alabama in the early 1990s. These facilities are both still in operation, but very little was done with the technology for many years.

One of the problems that compressed air storage faces is a thermodynamic effect where a gas heats up as it is compressed, which makes it increasingly difficult to store additional compressed air.

Although the storage conversion efficiency of CAES can be fairly high, the compressed air needs to be air as it is released, which typically requires an outside fuel source. The McIntosh plant in Alabama ends up burning an amount of natural gas to reheat the compressed air equal to about 1/3 of what it would use for direct combustion power generation. This makes CAES far less environmentally friendly than many other storage options. Overall, the efficiency of compressed air systems is also lower than many other storage systems, ranging from 45-70 percent.

Underground CAES systems also are reliant on location, much like pumped hydro systems. Suitable geological formations are necessary to have underground caverns that can be used to contain the pressurized air. However, it turns out these same formations are also desirable for natural gas storage, and, in the last decade, developers who were interested in setting up new CAES facilities often found that the gas industry was already using the available underground structures. Competition for access to suitable sites has also been a hindrance to development of CAES systems. But not all CAES systems are dependent upon locations with suitable geology.

Another compressed-air system being developed by a company called SustainX uses proprietary technology for isothermal compression (ICAES), which avoids the high temperatures and thermal losses. SustainX claims far lower costs than “conventional” compressed air storage, as well as almost 95 percent storage efficiency.

Instead of using caverns or geological formations, the SustainX method uses conventional, industrial, high-pressure bottles to store the compressed air. This enables the SustainX system to be installed anywhere, rather than relying on locations with salt domes or other usable geological formations. Because the process is isothermal, the air does not need to be heated or cooled, and, most importantly, there is no need to burn natural gas, which makes this approach preferable, particularly when it comes to storing power from clean, renewable sources. As yet, there are no installations of the ICAES system, but SustainX plans construction of a demonstration pilot plant to be completed in 2013.

Another especially interesting version of compressed air storage is the Energy Bag. Whereas in most instances, high pressure vessels or rock formations are used to contain the air under high pressure, the energy bag is a lightweight (75 kilograms or 165 pounds) bag that can store pressurized air sufficient to provide 70 megawatt hours of storage. The trick is that it does so deep underwater, where water pressure from the surrounding ocean provides the containment.

A 20-meter (65.6-foot) diameter Energy Bag at a depth of 600 meters (2,000 feet) needs no additional structure to withstand the great pressure of air stored within. The greatest drawback to the Energy Bag is that its application is limited to locations with ready access to fairly deep water, making it best suited for use with off-shore wind turbines. However, there may be some near-shore wave and tidal power generating applications that could also take advantage of this system, as well.

Like SustainX, the Energy Bag is a developmental system still going through testing. An initial investigation was begun off the coast of Scotland in the summer of 2011. Initial studies indicate that the Energy Bag offers a potential storage efficiency of more than 85 percent.

Main photo: Energy Bag, credit Thin Red Line Aerospace
Secondary images: CAES-Huntorf, credit U.S. Dept. of Energy; CAES diagram, credit Sandia National Labs

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Some methods of power storage use chemicals to store an electric charge. Others use various ways of applying physics to create potential energy storage that can be tapped to produce power when it is needed. One of the most intriguing methods of potential energy power storage is flywheel power storage.

Other potential energy storage systems use static potential energy — in which the physical medium essentially sits still, waiting to be released — like the body of water in a pumped hydro system waiting to be released through the turbines to produce electricity. But in flywheel power storage, the energy is in a carefully balanced flywheel spinning at many thousand revolutions per minute. A flywheel can almost instantaneously be tapped to release power when it is needed.

Flywheel power storage units are large cylinders roughly the size of a small car, 7 feet (2.13 meters) in diameter and weighing roughly one and a half tons (1360 kilograms). The flywheels are sealed inside a vacuum chamber and are supported on frictionless magnetic bearings, so that there are virtually no losses once the flywheels are spinning. They spin at up to 16,000 RPM, meaning the outer rim of the flywheel is moving at about 1,500 miles per hour (2,400 kilometers per hour). The magnetic bearings allow the flywheel to float inside its enclosure without any physical contact or wear, leaving the flywheel with a life expectancy of at least 20 years.

A single flywheel unit is able to store and deliver 25 kWh of extractable energy, and can operate through thousands of charging and discharging cycles. The sealed vacuum and frictionless environment makes flywheel storage systems low-maintenance and long-lasting, and the system does not require the use of potentially hazardous chemicals.

Because flywheel power storage is a rather industrial system, it does not require any particular location characteristics, and is well suited for urban and rural installations. The flywheels are typically installed with the cylinders buried in the ground to provide additional protection in the case of a possible mechanical failure, which could result in shrapnel from a disintegrating flywheel shooting off in all directions at high speeds.

As a segment of the energy storage market, flywheel storage suffered a significant setback when Beacon Power, one of the leaders in the field, was forced to file for bankruptcy near the end of 2011. Despite this setback, Beacon was acquired by another company and is continuing to develop additional power storage facilities using their flywheel technology.

The system efficiency of a flywheel energy storage system is around 85 percent. This efficiency, combined with its fast response time, also makes flywheels an excellent system for providing uninterruptible power supply for locations with power-critical needs like data centers and hospitals. Although the initial capital costs for these systems are higher than other battery systems, the flywheels take up less space and need much less maintenance than battery systems, which makes them cost-effective over their lifespan.

The largest flywheel storage facility is a 20 megawatt plant at Stephentown, New York which is connected to the New York state grid.

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Baumgartner has many safety precautions in place for his jump, including the latest technologically advanced gear built by specialized engineers. When he leaps from a balloon filled with helium floating at the cusp of the earth’s atmosphere, Baumgartner will don a pressurized space suit that traces its origins to the orange suits astronauts wear at launch and will protect his blood from boiling at such great heights. Reaching 120,000 feet above Roswell, New Mexico will take time, two and a half hours to reach the planned height, while the free fall will only take about 10 minutes before Baumgartner opens his parachute.

While a dangerous plan even with so many precautions and so much preparation, Fearless Felix is no novice to daredevilish dives. In July he succeeded in a 18.3 mile skydive from the Red Bull Stratos balloon, where he reached a top speed of  536 mph. This time, he’s hoping to move faster than sound moves through air. If successful, Baumgartner will become the only human to travel that fast outside the safe walls of a machine.

A member of Baumgartner’s team, Joe Kittinger, holds the previous record for the longest jump from space. In August 1960, Kittinger lept almost 20 miles; in October 2012, he’ll assist his successor through radio communication from the ground below.

Barring any other delays, the attempt has been postponed just a bit longer: until Thursday, October 11. When the mission is finally a go, fans will be able to cheer him on and watch the jump live in high definition here.

Featured photo credit: Reistlin Magere/Shutterstock.com

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Many people are not familiar with flow batteries, which are a type of chemical battery well suited for large-scale power storage. Though the technology is fairly new, flow batteries currently offer a conversion efficiency between 65 and 75 percent, with the potential for increased efficiency as the technology develops.

Most batteries contain chemicals that react with one another to produce a charge, which is the source of electron flow. However, as reactions take place and the chemicals become depleted, it becomes harder and harder for a battery to provide the same level of energy. This wear signals a need for single-use batteries to be replaced and rechargeable batteries to be charged.

While some batteries can be drained fairly far and then recharged (known as deep-cycle batteries), depleting a battery too far tends to cause chemical reactions among the constituent materials that cannot be undone by recharging. Depletion can cause chemical crystallization, resulting in lessened battery capacity over time.

Batteries tend to lose some capacity as soon as they are put to use, because chemicals remain even after they react and become inactive. The inactive chemicals take up space in the battery and prevent some remaining active chemicals from interacting, thereby lessening capacity.

Now, imagine if you were able to connect a battery to a big tank full of reaction-producing chemicals, and that you could flush out depleted material and replace it with fresh material as the battery was being discharged. That, in essence, is how a flow battery operates. Rather than wrapping up all the material in cells, fresh material can flow into the battery cell as depleted chemicals flow out. When recharging the battery, the pumps are reversed. In this way, flow batteries are much like pumped hydroelectric systems; however, flow batteries function with chemicals in a compact space rather than using potential energy of water behind a dam.

Considering most of the flow battery chemicals sit in an inert tank, and are not in contact with any of the active parts of the battery, a flow battery can remain sitting without losing any of its charge. Likewise, flow batteries can be fully discharged and remain in that state for a long period of time without suffering damage when it is eventually recharged. Because the capacity of the battery is driven by the volume of its tanks, rather than needing to construct more complicated battery assemblies, it is relatively easy to add capacity to a system by increasing the size or number of tanks for the system.

At present, the most common form of flow batteries use vanadium in different oxide forms. Vanadium is a rare earth metal primarily used in industrial applications as an alloying element for strengthening steel. By using different oxides of vanadium with different charge states, the battery chemistry in vanadium flow batteries is simplified and does not suffer any long-term degradation or contamination of the electrolyte, since vanadium and vanadium oxides are the only chemicals in the system.

Non-vanadium flow batteries also exist, and some of those have the potential to provide increases in power density. As with other technologies that rely on scarce minerals, the global vanadium supply could play a role in further development of flow batteries, and whether or not they can be cost-effective in the future. The first mine in the United States to extract vanadium is under development in Nevada and is expected to begin production later this decade. The company behind this project is focusing on the battery market.

Flow batteries are a relatively new technology. Although originally dating back to the mid-1950s, most of the research leading to their development was carried out by NASA in the 1970s and by scientists at the University of New South Wales in the 1980s, where the contemporary, vanadium-based version was patented. The largest flow battery installation is a 1.5 megawatt facility at a semiconductor factory in Japan.

The technology offers relatively low energy density in terms of energy storage per pound of material–even compared to heavy storage systems like lead-acid batteries–which does not make them good candidates for mobile applications. For stationary power storage purposes, however, this is far less a critical factor than it is for vehicles or for portable electronics. Flow batteries’ high level of rechargeability and relative safety (compared to lead-acid batteries, which release dangerous hydrogen gas) and stability make them potentially well suited for further development for moderate-scale power storage systems.

Flow batteries are also useful as large-scale backup power supplies because of their ability to quickly respond (within fractions of a millisecond) to demand for power. Because of their long life expectancy, they would also do extremely well for load-shifting, where electricity is used to charge the battery during off-peak hours when rates are low, and then provide power back to a facility from the batteries instead of paying the premium, peak electricity rates.

Main image credit: University of New South Wales

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The majority of bicycles you’ll find on the market today are built from steel, titanium, aluminum or carbon fiber. But bicycle design is constantly evolving, and designers and engineers are always testing out alternative materials. While some of these materials offer little more than an aesthetic appeal, many others offer genuine cutting edge advancements over standard components.

Chances are you’ll find something you like on this list whether you’re a hipster, engineer or environmentalist. Here are some of the top bikes made out of alternative materials:

Photo Credit: Renovo

Wood

Nothing looks quite so vintage as a polished wooden bicycle. Wood is probably most used as a frame material due to its aesthetic appeal, though it also has a number of performance advantages that shouldn’t be ignored.

Take for instance this beautiful wooden-framed bicycle by Renovo (pictured above). According to the folks at Renovo, wood frames are lightweight and offer superior shock absorption. Wood’s fatigue life rivals carbon and is substantially longer than aluminum or steel, and it also won’t dent like metal frames can.

Because wood is renewable, it is more eco-friendly too. And since it is a relatively cheap and abundant resource, it is ideal for bicycle construction in remote communities, such as in East Africa.

For a more diverse look at how wood has been utilized as a material by bicycle designers, check out this thorough roundup at Mother Nature Network.

Photo Credit: Segal

Magnesium Alloy

Segal bikes, a company out of the bike-friendly nation of The Netherlands, specializes in bicycles made from magnesium. Since magnesium has only about 64 percent of the density of aluminum, a chief advantage of this material is that it is ultra-lightweight. (About 35 percent lighter than aluminum and 75 percent lighter than steel).

According to Segal, magnesium bikes are also superior at absorbing energy, making them a more comfortable ride. Eco-conscious cyclists can also rest assured that they are fully recyclable.

You can customize your own magnesium-framed bike at Segal here.

Photo Credit: Boo Bicycles

Bamboo

Bamboo might be the trendiest alternative bike material for the eco-conscious consumer, and for good reason. Because bamboo is a fast-growing grass, it is as abundant as it is renewable.

It also looks great, and performs even better. Bamboo’s durable, hollow shaft seems purposely designed by Mother Nature for bicycle construction. Some of the material’s principle advantages include improved vibration damping and high crash tolerance. It also offers a smooth and comfortable ride even over harsh terrain. The fact that a bamboo bike blends in with its natural surroundings on the trail just adds to its aesthetic appeal.

There are a number of designers specializing in bamboo on the market today, but a notable one is Boo Bicycles. Their bikes are among those which have been raced at the highest level by professional cyclists.

For a nice roundup of some of the other options available for bamboo bikes, check out TreeHugger’s list here.

Photo Credit: EADS UK via bikeradar.com

Nylon

Could a functional bicycle really be made out of nylon? Thanks to some Space Age technology, yes it can. Not only is this bicycle made from nylon, but it is actually as strong and sturdy as steel.

Designed by development engineers Andy Hawkins and Chris Turner of the Aerospace Innovation Centre, the bike is constructed of successive, one-tenth-of-a-millimeter-thick layers of fused nylon powder. The manufacturing method was borrowed from a process also used in the construction of satellites.

Though this prototype’s unusual design is not exactly ideal for the professional cyclist, a more practical version is supposedly in the works. Who knows, this might just be the future of high-performance bicycles.

A video by the BBC featuring more about this bike’s construction can be seen here.

Photo Credit: videonatelinha/Youtube

Plastic

Plastic is unfortunately one of the most ubiquitous materials around today, and since most plastics are not biodegradable, they don’t make for very eco-friendly construction materials. But what about recycling some of that plastic and using it to construct eco-friendly bicycles? That’s making the most out of a bad situation.

One inventor in Brazil is doing exactly that, creating the Muzzicycle. Built entirely from plastic collected in some of Brazil’s largest landfills, Muzzicycles turn trash into transportation. At their website they even keep a running tally of how much plastic they are able to recycle annually. The bikes are also economical and can be bought over the internet for only about $140.

You can view a CNN report about how the bikes are constructed here.

Photo Credit: Giora Kariv/Vimeo

Cardboard

Cardboard is probably the last material you would choose to construct a bicycle with. It might even seem like an impossible feat. But that’s just because you aren’t as inventive as engineer Izhar Gafni, designer of the world’s first completely practical cardboard bicycle.

Gafni’s inspiration was the physics of origami. By folding cardboard over itself in the right way, he found that it could actually be made remarkably sturdy. Gadfi admits that his first prototypes “looked like delivery boxes on wheels.” But just take a look at the finished product: it’s not only functional, but pretty stylish too.

They are “strong, durable and cheap,” according to Gafni. He estimates they could sell for as little as $60 each.

Though the bikes aren’t ideal for the high performance cyclist, they are entirely suitable for the eco-conscious, casual commuter. Check out a short documentary about how Gafni constructs the bikes here. You may have to see it to believe it.

Photo Credit: Onyx via bikemoments.com

Hemp

Is there anything that can’t be made out of hemp? The Onyx Hemp Bike by Onyx Composites makes use of cannabis in a way you might not have imagined possible before.

To build the bike frames, hemp fiber is dunked in epoxy resin and wrapped around a styrofoam core. The resultant frame ends up being 60 percent hemp and 15 percent bamboo, with the rest made from carbon and aluminum.

According to Nicolas Meyer, the engineer behind the design, the formula creates a frame that is sturdier than bamboo or carbon fiber alone.

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Batteries are the first thing most people think of when it comes to power storage, because that is what we are most familiar with in our day-to-day lives. Batteries are packages that store energy in chemical form until it is needed.

At the consumer level, some batteries are single-use, and cannot be easily recharged after they have been depleted due to the kinds of chemical reactions they rely on to provide power. Single-use batteries may be convenient for consumers, but they are not viable for significant power storage. At grid scale, batteries must be able to be charged when there is extra electrical production and discharged when there is extra demand.

One problem that most kinds of rechargeable batteries suffer over time is a loss of capacity. The repeated charging and discharging of the battery will lead to some of the chemicals crystallizing, and thereby losing the ability to store power, which leads to battery degradation over time.

Even if there is no demand on the battery, there will be a gradual discharge of the battery over time. Monitoring of the charge level of the battery can aid in keeping it kept fully charged until its power is needed. Typically, the stored power will be used within a few days and then the battery will be recharged again.

Unlike the batteries in your cell phone or laptop computer, the batteries for grid-level power storage use different kinds of chemical combinations for more efficient power storage. Chemical batteries such as sodium-sulfur batteries offer large-scale methods for storing power. Flow batteries are another specialized type of chemical battery that offer some unique features that can make them attractive in some cases. (We will take a look at flow batteries in a separate, forthcoming article.)

Sodium-sulfur batteries are one kind of liquid metal chemical battery that is used in large scale power storage. The properties of sodium-sulfur batteries make them unsuitable for most uses other than industrial level uses. Sodium metal is a hazardous material that will spontaneously burn if it comes into contact with any moisture, so it particularly needs to be kept in a contained environment.

Sodium-sulfur batteries also need to be kept hot, and have an operating temperature of 300-350 degrees C (572-662 degrees F). This makes them unsuited for more mobile applications, but larger scale installations can be thermally efficient and can work better than smaller sized batteries. The process of charging and discharging the battery generates a fair amount of heat, so that, once it is in operation, a sodium-sulfur battery does not usually require external heat to keep it at its working temperature.

The relatively low cost of materials needed for sodium-sulfur batteries makes them affordable, particularly in comparison with other types of batteries using rare and exotic materials that can be expensive to obtain. Sodium-sulfur batteries also have a good energy density, so a large amount of storage is able to be contained in a small space.

Sodium-sulfur batteries have an efficiency of around 90 percent, which makes them particularly effective for power storage. The largest sodium-sulfur battery installation is a 34 MW installation at Futamata wind farm in northern Japan.

Other kinds of battery grid-storage systems are also beginning to be used, as well. Manufacturers such as A123, which is a manufacturer of batteries for vehicles (BMW, Fisker, VIA Motors, etc.), also manufacture grid storage units with a number of installations throughout the world providing several megawatt-hours of power storage capacity. An installation at the Laurel Mountain wind farm in West Virginia is similar in size (32 MW) to the Futamata wind farm.

Other types of battery chemistries are also being explored for other cost-effective ways of storing electricity, though pumped hydro is still overwhelmingly the most common method for power storage. At the high tech end, some of the most advanced battery research is going on in the automotive industry, where battery manufacturers are looking to extend the range and performance of electric vehicles. Those developments are likely to find applications in other power storage systems, as well. At the other end, scientists are developing solutions for power storage using materials as basic as iron and air (essentially using the process of rust for power storage).

Main photo: Minwind battery storage in Luverne, Minn. Credit: Four Peaks Technologies

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In the past several decades, global plankton populations have declined due to climate change. Because human life depends on the presence of these oxygen-producing creatures, marine biologist Chris Bowler is working to study plankton as much as possible before they disappear. Bowler and a team of other scientists have been collecting plankton samples across the world for the past 2 1/2 years as part of the Tara Oceans expedition.

The expedition was a massive effort along a 62,000 mile journey, visiting 32 countries with a total 196 people who took turns aboard (126 scientists, 24 journalists, 7 artists, 8 cooks, 23 sailors, 3 customs officials, 1 doctor, 4 guests). The expedition cost about 9 million euros.

An ideal study of climate change impact on plankton populations would involve monitoring the same location over a period of time, watching what happens to the various species of microorganisms as time passes. The Tara Oceans team, however, collected samples from around the world, and will use that data to determine which plankton are likely to migrate, thrive or go extinct as certain conditions arise in waters across the globe. The expedition has collected approximately 27,000 samples, which the team will study to determine which varieties of plankton prefer particular habitats (more polluted, more acidic, etc.) and have a better understanding of which species will be able to survive forecast conditions.

The team has discovered up to one million new species of microorganisms. It will take years to sift through all of the samples, by which point some species may already be extinct. Hopefully, however, the research will show a great enough population of plankton will be able to live in warm, acidic waters.

Main image: plankton mix from scientific station 146. Credit: C. Sardet/CNRS/Tara Oceans

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