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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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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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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Located near Arlington, Ore., the project consists of 300-plus wind turbines staggered over 30 square miles in the eastern part of the state. Construction of the Shepherds Flat wind farm began in 2009, and despite controversy over funding and a delay by the Air Force, progressed fairly quickly for a project of such size. The installation has a 20-year power purchase agreements with Southern California Edison, and was one of the first to use the U.S. Department of Energy’s loan guarantee program.

Besides producing an estimated 2 billion kWh each year, Shepherds Flat is expected to have an annual economic impact of $37 million for the state. Sustainable Business Oregon reports that New York-based Caithness Energy employed more than 400 people to develop and will employ another 45 full-time workers.

In 2007, the state legislature created a renewable portfolio standard (RPS) that requires the largest utilities in Oregon to provide 25 percent of their retail sales of electricity from newer, clean, renewable sources of energy by 2025. In addition to wind and solar energy, a recent survey shows that Oregonians strongly favor the development of tidal power resources as well. Ocean Power Technologies plans to deploy at 150-kilowatt “PowerBuoy” off the coast near Reedsport.

Photo credit: Loco Steve/Flickr

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As a country, China has made solar panel manufacturing a key part of its economic agenda. After huge increases in production, prices dropped 75 percent over the last three years. For the renewable energy world, it was a huge boon. Falling prices helped make solar panels easier and easier for homeowners to afford. But the U.S. government, worried about competition to American solar manufacturers, slapped a huge tariff on all Chinese solar panel imports, slowing sales here.

In Europe, demand for solar panels has slowed as some government rebates and other incentives have been reduced or ended. Chinese companies that relied on demand from European countries are now suddenly faced with piles of excess stock. Some European countries are also now considering following the United State’s example and raising prices on Chinese panels, arguing that they are being dumped on the market.

Chinese solar stocks have plummeted, and the companies are struggling. In response, the Chinese government asked local governments to create new plans for adding solar power to their grids. Shanghai, Beijing, Tianjin and other states are involved. Right now, only 1 percent of China’s electricity comes from solar. The country is the largest producer and consumer of coal in the world, and their coal use alone is responsible for more than 15 percent of world carbon dioxide emissions. China can use every bit of solar power that can be installed.

Unfortunately, the U.S. needs much more solar power as well. The U.S. decision to raise prices on Chinese solar panels slowed solar growth just when it’s most critical for renewable energy to grow. Here’s hoping the Chinese solar companies survive.

Image credit: Zhu Difeng/Shutterstock

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Hyundai has leased 15 ix35 FCEV’s to Copenhagen for use as municipal vehicles, taking delivery of the cars in the spring 0f 2013. Experts characterize the deal between Hyundai and Copenhagen as a “win-win” for both parties. Considered one of the greenest cities in the world, the Danish capital aggressively pursues its goal of becoming 100 percent carbon neutral by 2025, and implementation of FCEV technology plays a key role in achieving that goal. For their part, Hyundai gets a real-world proving ground for what they believe will ultimately surpass battery-electric technology with its inherent range limitations and lengthy “refueling” time.

Advantages and challenges of fuel cell vehicles

Fuel cells power a vehicle when hydrogen reacts with atmospheric oxygen through a “fuel cell stack,” producing electric power to drive a motor. The only waste product is water. FCEVs have a range similar to gasoline-powered cars (the ix35 has a range of about 365 miles) and can be refueled in minutes — much faster than the hours required for a battery-electric. That’s assuming there’s a hydrogen refueling station anywhere nearby. And therein is the rub. With a battery-electric car, the fuel source is ubiquitous, even if it doesn’t get you very far. Add to that the current estimated initial price tag of $88,000 for a FCEV and the principal challenges to fuel cell technology becomes apparent.

But Hyundai and other FCEV developers are confident those challenges will be met — and soon: “We aim to reduce prices of fuel-cell vehicles to match battery cars by 2020-2025,” says Hyundai’s director in charge of fuel cell research Lim Tae-won. With plans from companies like Germany’s Linde to half the cost of building hydrogen refueling stations and carmakers like Hyundai aiming to cut that $88,000 price tag in half as it rolls out up to 100,000 FCEV’s by 2020, Tae-won sees FCEV’s as ultimately a better choice than battery-powered cars.

Main image credit: Revolve Eco-Rally/Flickr

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In Tallahassee, Nopetro L.L.C. unveiled its state-of-the-art compressed natural (CNG) facility, making natural gas a real solution to expensive, polluting transportation. The station is the first part of a planned regional network to service privately owned CNG vehicles, government and commercial fleets.

Also expected to make use of the stations will be the Leon County School District, which is planning to transform its entire fleet of school buses to CNG. In addition, a portion of each sale will go to the school district.

Expectations for the planned network are high. Putnam hopes it will not only provide consumer goods with a practical, environmentally friendly way to travel across the state, but that it will also produce cost savings, benefiting consumers and the local economy. He hopes those savings will make it to local schools and governments, and eventually to taxpayers.

“This partnership is exactly what our legislature had in mind when it established natural gas as a key component of the state’s transportation policies,” said Putnam. “A network of natural gas fueling stations in major cities across our state will encourage commercial fleets and individual consumers to make the move into Florida’s energy future.”

Nopetro announced 18 additional cities that it plans to target in the next three years, including three in Georgia.

Natural gas can be environmentally dangerous to extract, leading many environmentalists to warn against its use. But it is also 33 percent cleaner than diesel and 25 percent cheaper, meaning that for better or for worse, it is here for the long haul.

Main photo credit: Nopetro L.L.C.

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According to a press release from Sharp, while the new panels can be used in a conventional manner mounted on the roof they were designed primarily to be used as protective porch railings or as in-place window glass. The semi-transparent black panels are lacking the metal frame found on typical panels and instead are constructed mainly of laminated glass filled with photovoltaic cells. They are each 4.5 feet wide by 3.2 feet tall and only 0.37 inches thick, which is much thinner than standard panels found on the market today.

One downside? They have a maximum power output of only 95 watts with around 6.8 percent efficiency, which is far below the 20 percent efficiency being produced on today’s modern solar panels. However, while they may not be as efficient they are semi-transparent and thus can be integrated anywhere glass is used in building construction. Sharp hopes to eventually integrate the panels directly within building materials so that any available glass surface can be used as a power-generating solar panel.

In the meantime, if we could retrofit every high-rise building’s standard windows with this solar panel glass, buildings would each become its own power plant capable of generating at least a percentage of its energy needs. The new panels will be launched in Japan on October 1 but no word yet on price nor availability dates in the U.S. Let’s hope it sooner rather than later.

[via CNET]

Image Credit: Sharp Japan

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In the Green Power Community Challenge, communities from across the country compete in renewable energy use. The program gives out two awards: one for the community achieving the highest percentage of green power in electricity use, and one for the community using the most green power.

Thirty-five communities participated, with representation coming from Illinois, Maryland, Oregon, Pennsylvania, Wisconsin, Washington, California, Connecticut, Utah, Texas, Missouri and the District of Columbia. (Sure Oregon and California are expected to join any efforts toward renewable energy, but notice red states like Utah, Texas and Missouri are in the competition there too!)

And this year’s winners are…

• Washington, D.C., Green Power Community, which took home the prize for most kilowatt-hours of green power. Over the last year, D.C. government, businesses and residents used their collective purchasing power to buy more than 1 billion kWh of green power, constituting more than 11 percent of the district’s total electricity use.
• Oak Park, Ill., Green Power Community, which came in first for the highest percentage of green energy. Oak Park used clean energy to achieve an astounding 91.9 percent of its total electricity needs.

According to the EPA, the challenge blew past its original goals. Participants in the program used a collective 5 billion kWh of sustainable energy in the past year – the greenhouse gas reductions are equal to what would be done by turning off the electricity in 426,000 homes.

The EPA is continuing the program, currently inviting communities to participate in the 2012-2013 challenge. Winners get bragging rights and “special attention from the EPA.” This year’s achievements are certainly respectable, but imagine what kind of impact would be possible with a shinier prize. (Just a suggestion!)

Main photo credit: Johan Swanepoel/Shutterstock

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