Friday, July 13, 2012

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.

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