Two New Methods of Utility Scale Electrical Storage

Electrical storage technology is long overdue for significant innovations and breakthroughs. Applications from electric vehicles, to scalable emergency power backup systems, to power grid load leveling could all benefit immensely from improvements in energy storage. We take a look at two promising prospects below:

Brian Westenhaus takes a look at a new combination of supercapacitors and scalable flow cell batteries, as a possible future means of utility load leveling.

The Drexel’s team of researchers is putting forward a plan to integrate into the grid an electrochemical storage system that combines principles behind the flow batteries and supercapacitors that power our daily technology.

The team’s research has yielded a novel solution that combines the strengths of batteries with supercapacitors plus taking away the scalability problem. Their new “electrochemical flow capacitor” (EFC) consists of an electrochemical cell connected to two external electrolyte reservoirs – a design similar to existing redox flow batteries which are used in electrical vehicles.

The Drexel team’s new technology is unique because it uses small carbon particles suspended in the electrolyte liquid to create a slurry of particles that can carry an electric charge. The uncharged slurry is pumped from its tanks through a flow cell, where energy stored in the cell is then transferred to the carbon particles. The charged slurry can then be stored in reservoirs until the energy is needed, at which time the entire process is reversed in order to discharge the EFC.

The EFC design allows it to be constructed on a scale large enough to store large amounts of energy and allows for rapid disbursal of the energy when the demand load needs it. _NewEnergyandFuel

A distinctly different approach to utility scale electrical storage is taken by General Electric, with its new ceramic electrolyte battery:

The key to the technology is a ceramic electrolyte material that separates the electrodes. During charging, chloride ions are released from sodium chloride and combine with nickel to form nickel chloride. The sodium ions that remain move through the electrolyte into a reservoir. When the battery produces power, the ions move back through the electrode and the reaction is reversed. The process takes place at about 300 °C, inside an insulated container.

...The batteries are more expensive per kilowatt-hour than lead-acid batteries, but they're expected to last longer, especially in applications in which the batteries are deeply discharged on a frequent basis, which damages lead-acid batteries. In some applications, lead-acid batteries might last only six months. Designed to be deeply discharged at least 3,500 times, GE's sodium-nickel batteries could last through a decade of daily charging.

...GE will have strong competition for new grid battery technologies from companies such as Aquion Energy and Liquid Metal Battery, the manufacturing giant clearly has high ambitions for its technology, recently forming a new business unit to commercialize the battery technology. Indeed, at the factory opening, the company announced an additional $70 million investment to increase its capacity to help meet a backlog of orders. "The cost of electricity over time is going to go down because [GE's battery] is going to give utilities the ability to use a multitude of different technologies at the same time," GE CEO Jeffrey Immelt told a group of reporters at the plant opening.

The first applications will be somewhat less ambitious. GE's first customer is a South African company—Megatron Federal—that will use the batteries to power cell-phone towers in Nigeria. Those are usually powered by diesel generators. Pairing the generators with the new batteries can help them run far more efficiently. "You save 53 percent on fuel, 45 percent on maintenance, and about 60 percent on diesel generator replacements," says Brandon Harcus, division manager for telecommunications for Megatron Federal. "For our Nigerian application, the savings are substantial, about $1.3 million over 20 years per cell tower. You use a lot less fuel and produce a lot less carbon."

For this application, the battery has two primary advantages over the lead-acid batteries that sometimes back up the generators. They can charge faster—over two hours compared to 10 hours for lead-acid batteries. And unlike many other batteries, GE's new battery doesn't require air conditioning, which helps reduce fuel consumption at the site.

Besides powering cell-phone towers, the batteries could also be used to store power from wind turbines and solar panels to even out fluctuations in these power sources. GE also says they could be used in microgrids, small grids that are often the size of a village or military base and are designed to operate independently of the larger electrical grid while still getting grid-quality electricity. _TechnologyReview

These are very interesting technologies, and deserve to be tested in the real world to see what they can do.

Unfortunately, they are being promoted as technologies which can remedy the faults of intermittent unreliable approaches to energy, such as big wind and big solar. The swings of intermittency in big wind and big solar are unfortunately too large to allow for the affordable use of energy storage for large grid backup, with these or any other technologies currently in the pipeline.

Much better to promote these useful technologies for what they can do, rather than to promise things which cannot be delivered for many decades yet. And by then, people will wonder why anyone would be willing to go to so much work and expense for the sake of inherently flawed approaches to energy production, such as big wind and big solar.

Who Needs Rare Earth Magnets? Not NovaTorque

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Sunnyvale California's Nova Torque has introduced 3 permanent magnet motors that use magnets costing only 1 / 15th the cost of a neodymium magnet.

So how does NovaTorque do it? Take a look at the photo. The motor (foreground) consists of conical hubs (background) containing magnets separated by a tapered motor shaft (left). The hub is the component that looks like a space capsule and the shaft has the band of copper. The key here is that the interface between the magnetic surface of the hub and the shaft is diagonal, not flat like in most motors. A diagonal interface dramatically increases the surface area between the two, thereby increasing magnetic flux transmission (good) and reducing materials (also good). The magnets are the raised surfaces on the side of the conical hub.

Think of how baguettes get cut in restaurants: you can put more butter on diagonally cut bread than slices lopped off the top. The expanded surface area permits NovaTorque to switch to ferrite magnets.

NovaTorque also manages to reduce the amount of copper needed for the coils in the motor. Less copper, less cost.

Efficiency in the motor is greater than average due to the fact that the magnetic field is axial, i.e., it runs in an oval around the axle, instead of being radial, i.e., circumnavigating it. One advantage: the axial field means NovaTorque can use gain-oriented transformer-grade sette, which lowers eddy current losses and boosts efficiency. Higher efficiency should also result in fewer breakdowns: a large percentage of mechanical failures can be traced to ambient waste heat generated by motor inefficiencies.

The motor also pairs well with variable drives, and variable speed air conditioners are one of the top priorities in data center retrofits.

The company's Premium Plus+ motors are currently spec'd for refrigerators, HVAC systems, vacuum pumps and industrial equipment. But if the technology scales well to larger motors, other markets could open. _greentechmedia

In other news from GreenTechMedia, Massachusetts company Premium Power is introducing a zinc bromide flow battery system scaled for a large home. It is clear from the comments following the article that most readers have no idea what a flow battery is. Still, the announcement is good news for anyone looking for advances in large scale power backup systems.

Also from GreenTechMedia, an announcement that Sapphire Energy is beginning work on the first of a series of 3 100 acre algae biofuel pilot plants in New Mexico. Ignore the facetious comment left by yours truly after the article. The website will probably alter the article by the time you read it to make the comment seem superfluous, or may delete the comment altogether. Website administrators tend to take themselves and their sites altogether too seriously! ;-)

Brian Wang describes research from Montana State University, which demonstrates that algae are capable of thriving on added HCO3 -- producing significantly more oil as a result of the extra carbon. This is actually good news for those worried about ocean acidification from atmospheric CO2, since most dissolved CO2 turns promptly into HCO3 (over 90% I believe). In other words, sea creatures will take this extra bicarbonate and turn it into more plankton, sponges, coral reefs, and shelled sea creatures.

Robert Rapier describes a visit to a Shell Oil Gas-to-liquids plant in Malaysia. The plant utilises gasification plus F-T synthesis of liquids. Very enlightening, and most optimistic toward the future of GTL.

CTL and BTL are still considerably more expensive, but given time we are likely to see a lot of progress on those fronts as well.

Vanadium Redox Flow Cells At Work in Canada and Alaska -- A "Game Changer"

Utility-Scale flow cell batteries promise a "perfect fit" with large solar and wind energy projects. In Canada and Alaska, VRB Power Systems Vanadium flow cells are already helping to smooth the output of wind turbine projects.

VRB vanadium flow battery technology is already smoothing wind turbine output for remote power hybrid wind-diesel applications in northern Canada and Alaska and providing frequency regulation, voltage support and blackstart capability.

These locations have turned to wind power because electricity costs have become unreasonably high due to the growing costs of diesel generation and to gain the environmental benefits associated with a renewable resource. A VRB flow battery is introduced to the hybrid wind-diesel system to firm up the wind power and to ensure that the generator runs on the most efficient setting. "With the current high cost of diesel in these remote communities, the pay-back for investments in storage is very attractive," said Brian Beck of VRB Power Systems. VRB claims that solar can also be added to this system.

Another promising utility-scale electrical storage method is the Sodium Sulfide (NaS) battery from NGK Insulators, Ltd., Japan.

With over 200 megawatts (MW) of NaS batteries installed worldwide, Japan-based NGK Insulators, Ltd is another battery storage company hoping to capitalize on that rapidly growing market. The company's NaS batteries, used mainly for load leveling, enable companies to sell cheap off-peak wind power during peak times, thereby fetching a higher price. There are 34 MW of these batteries being installed near the 51-MW Rokkasho wind farm, making it the largest combined wind and storage project in Japan. Stored indoors to protect them from the corrosive salty air of the region, 17 sets of 2-MW NaS battery units (each battery unit consists of 40 50-kW modules) are monitored alongside the weather and the Rokkasho wind farm in a control center.

New technological applications such as the sophisticated vanadium flow batteries of VRB Power and the NaS systems of NGK combined with a variety of other storage options such as pumped hydro and compressed air systems demonstrate that the intermittency concerns often associated with renewables like wind and solar are quickly becoming manageable issues.

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Pumped hydro and compressed air systems do not have ideal availability or scalability. That is why the development of the redox flow cell and other scalable electric storage methods are so important to the rapid expansion of solar, wind, and other intermittent renewable energy schemes. Not to mention routine load-leveling which would save utilities significant sums of money every year, once implemented.

Flow Cells for Home Energy Use

Flow cell batteries represent a technology that is more often touted as a utility load-leveling tool. But a home-scale version of a flow cell battery is being sent to Beijing for the 2008 Summer Olympics, as part of the Zero Net Energy Future House USA display.

... the cell's design is different than a traditional battery, with fluid charged with electrolytes flowing past its cell membranes, said Kevin Dennis, vice president of sales and marketing for ZBB.

"There are a couple of advantages (with this design)," he said. "Once the cell is charged, you can turn it off. A battery is always on." ZBB's fuel cells are designed for large energy efficient homes, commercial and industrial properties and power relay stations. When they're not in use, ZBB Energy's fuel cells discharge at a much slower rate than batteries, Dennis said. The fuel cells are rechargeable, and can be recharged many more times than rechargeable batteries. "We design fuel cells like this on the order of 20 to 30 years," he said. "You will have to replace the (cell) membrane in about 10 years. The cycles are on the order of thousands."

The ZESS 50 is ZBB Energy's 50 kWh energy storage module. ZBB Energy also makes the ZESS 500, which can store up to 500 k Wh. ZBB Energy has piloted its fuel cells for the past four years, Dennis said, and began production earlier this year. The company, which has 38 employees, manufactures the fuel cells from its 72,000 square foot facility in Menomonee Falls.

The Future House USA will be part of the Future House Village, a neighborhood of eco-friendly demonstration homes created by teams from Canada, China, Germany, Japan, South Korea, Spain, Sweden and the United States. The high-visibility program is designed to promote energy-saving strategies and construction that will have a minimal impact on the global environment. __Source

The term "fuel cell" is a misnomer for this technology. The proper term is Zinc-Bromine "redox flow cell (PDF)." Presumably, the company uses the term "fuel cell" in its press releases due to greater public familiarity with the term (if not the underlying concept).

Matsushita in Japan produces a true home fuel cell, which will be placed outside some Japanese homes starting next year.

It is highly likely that both home fuel cells and home flow cells will enjoy much higher rates of utilisation within the next ten years, than most energy analysts anticipate. The main technological obstacle to greater utilisation of redox flow-cells is the low energy density. For that reason, it is likely that the larger uses of the technology will be for utility and industrial scale power backup and load leveling. Eventually, flow cells should move downscale to commercial buildings, hotels, apartments and condominiums, and single family residences.

Better Large Scale Battery Storage

Al Fin is always spouting off about the need for "utility scale energy storage" for load-leveling, and for bringing more renewable energy sources online--such as solar and wind. Al Fin's favourite technology is the redox flow cell, but other storage technologies are making a bid to play this very important role.

Using so-called NaS batteries, utilities could defer for years, and possibly even avoid, construction of new transmission lines, substations and power plants, says analyst Stow Walker of Cambridge Energy Research Associates. They make wind power — wildly popular but frustratingly intermittent — a more reliable resource. And they provide backup power in case of outages, such as the one that hit New York City last week.

Such benefits are critical, because power demand is projected to soar 50% by 2030 and other methods of expanding the power supply are facing growing obstacles. Congress is likely to cap carbon dioxide emissions by traditional power plants to curtail global warming. Meanwhile, communities are fighting plans for thousands of miles of high-voltage transmission lines needed to zap electricity across regions.

....American Electric Power (AEP), one of the largest U.S. utilities, has been using a 1.2 megawatt NaS battery in Charleston, W.Va., the past year and plans to install one twice the size elsewhere in the state next year. Dozens of utilities are considering the battery, says Dan Mears, a consultant for NGK Insulators, the Japanese company that makes the devices.

"If you've got these batteries distributed in the neighborhood, you have, in a sense, lots of little power plants," Walker says. "The difference between these and diesel generators is these batteries don't need fuel" and don't pollute.

The NaS battery is the most advanced of several energy-storage technologies that utilities are testing. The oldest and most widespread form of energy storage in the USA, pumped hydroelectricity, collects water after it spins a turbine and uses a small amount of electricity to send it back and repeat the process.

Lead-acid batteries — the same kind used in cars — were installed by Southern California Edison in 1988. But the batteries, though inexpensive, typically fill warehouse-size buildings and last about five years. That's because the acid that connects positive and negative electrodes corrodes components.

An NaS battery, by contrast, uses a far more durable porcelain-like material to bridge the electrodes, giving it a life span of about 15 years, Mears says. It also takes up about a fifth of the space. Ford Motor pioneered the battery in the 1960s to power early-model electric cars; NGK and Tokyo Electric refined it for the power grid.

Since the 1990s, Japanese businesses have installed enough NaS batteries to light the equivalent of about 155,000 homes, says Brad Roberts, head of the Electricity Storage Association. In the USA, AEP is using the 30-foot-wide by 15-foot-igh battery to supply 10% of the electricity needs of 2,600 customers in north Charleston, says Ali Nourai, AEP manager of distributed energy. The battery, which cost about $2.5 million, is charged by generators from the grid at night, when demand and prices are low, and discharged during the day when power usage peaks.

....A more intriguing goal is to wring more energy out of the wind farms that are cropping up across the country. Wind typically blows hard at night when power demand is low, producing energy that cannot be used. When demand peaks midday, especially in the summer, wind is often sporadic or absent. NaS batteries could let AEP store wind-generated power at night for daytime use.

Next year, AEP plans to install another NaS battery in West Virginia to provide backup power in case of an outage — the first such application of the technology, Nourai says. The battery would kick in automatically, so customers would see no disruption.

Other utilities are planning or considering the technology. In Long Island, N.Y., a group of utilities plans this summer to install an NaS battery at a bus depot. The battery is charged at night, when power prices are low, and discharged during the day to pump natural gas into tanks to provide fuel for the buses, says Mike Saltzman of the New York Power Authority. That cuts electric costs for the bus company and eases stresses on the grid. Pacific Gas & Electric is leaning toward installing a much larger, 5-megawatt battery by 2009, enough to power about 4,000 homes, says PG&E's Jon Tremayne.

....Meanwhile, other storage devices are gaining traction, too. A group of Iowa municipal utilities plans to use wind turbines to compress air during off-peak hours that will be stored in an underground cavern. The air would be released at peak periods to run turbines and generate power for about 200,000 homes. Another technology, the flywheel, has a massive cylinder that can spin for days after being started by a generator. The cylinder can then activate a turbine to supply electricity for a few seconds or minutes when it's needed, for instance, to head off an interruption to a computer center from a lightning strike.

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Homes, businesses, neighborhoods, and larger areas all need energy storage scaled to their needs. This is one of the more important energy issues at present, yet it gets relatively little attention.

Hat tip Fatknowledge blog

Making Solar Energy More Usable

The rate of solar energy intercepted by the earth is about 5,000 times greater than the sum of all other energy sources, but less than 0.5 percent is represented in the kinetic energy of the wind, waves and in photosyntheticstorage in plants. The amount of the solar energyintercepted by earth is only one thousandth of one millionof the total released energy in the sun. Source.

One of the main problems with harvesting solar power on earth, is the limited number of hours per day that sunlight reaches the surface. Using photovoltaics, you are limited to an average of six hours per day of usable energy production, minus time for bad weather. Often the periods of heaviest usage of energy are times that the sun does not shine.

One way around that problem is to place photovoltaic panels in earth orbit, well above the shadow of the earth. Generated power can be beamed to earth by microwave, and collected by large rectenna farms on the surface. Here is a link to a blog, Power From Space, devoted to this topic.

Another method is to collect the sun's energy while it shines, and store the energy for later use. This method does not collect nearly as much energy as the orbiting solar satellites, but the sun provides so much extra energy to earth that it will suffice. What is the best method of storing solar energy?

Batteries are no good, because the energy density of batteries is too low, given their cost and short lifetimes. The only possible exception in terms of current battery technology would be redox flow cells. In five or ten years, redox flow cells might be ready for the challenge.

Electricity is hard to store at the present time. But energy comes in many forms, and is convertible from one form to another. I would like to suggest that with present technologies, the best form of solar energy storage is thermal storage--heat. Below are several links providing more information about thermal storage. In future posts, I will provide more detail regarding current efforts to utilise this important energy storage method.

Wiki
Purdue
Open Directory Thermal Energy Links
Ionic Thermal Storage
Dissertation on Phase-Change Heat Storage Systems

Thermal storage is a type of energy averaging. Rather than being forced to use all the six hours of sunlight at one time, the energy can be used over the entire 24 hour period. Solar Ponds are one form of thermal storage. OTEC is another, and in that sense the ocean itself could be thought of as a huge thermal system.

Humans need heating and cooling, and in that sense thermal storage will always be useful for human buildings and infrastructure. Eventually, for electric power purposes, redox flow cells and other newer electrical storage methods will eliminate the need for thermal-electric conversion losses.

Flow Cell Energy Storage: A Hybrid Storage Technology

The Energy Blog reported a while back on a new energy storage technology, Vanadium redox flow batteries. Flow batteries are called that because the electrolytes flow through the cells, giving up electrons to an external circuit. The redox reaction is reversible, so the cells can be charged or discharged. The significant fact about flow batteries is the potential to scale to very large storage sizes into the megawatt and multi-megawatt ranges. This is the type of storage capacity utilities have been looking for.

Performance

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The VRB has an availability of greater than 98%. Designed for unattended operation with very low maintenance costs.
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No degradation from repeated deep charges and discharges. The system can be discharged and charged greater than 13,000 times (20% to 80% SOC) without deterioration in system efficiencies.
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System round-trip efficiencies between 70% - 78%.
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The VRB-ESS has a charge/discharge window of 1:1 - allowing off-peak charging for on-peak dispatch - a fraction of the time required by other battery systems and ideal for wind generation applications.
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Cross mixing of electrolytes does not lead to contamination of electrolytes
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indefinite life of electrolyte (no disposal or contamination issues).
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Once charged, the electrolyte remains fully charged with low self-discharge.

Flow batteries are not generators, like regular fuel cells. Most fuel cells use up their fuel sources in an irreversible reaction. Flow batteries do not use up their electrolytes. The electrolytes are fully reusable, with recharging. And flow cells are not like regular batteries, since you recharge them by replacing the electrolyte. They are a new, hybrid form of chemical battery/fuel cell.

The best use for these cells will probably be as load levelers for utilities, and as backup power for large industrial facilities.

Here are more links:

Sandia
Wiki
ME
Geo