Recharging the Power Grid

[gulfcoastliberal]

Two year old article, probably been posted before, but still relevant and still interesting:

Fighter jets scream over Columbus Air Force Base, a sprawling military facility in eastern Mississippi that is especially busy these days training aviators for the war on terror. But for all the high tech aeronautics on display overhead, the bustling Air Force base often relies on an old-fashioned diesel generator to keep radar and communications humming and the jets from colliding. That's because the region's antiquated, overloaded power grid dishes out 25 blackouts a year, as well as another hundred or so voltage fluctuations that crash sophisticated flight simulators.

The solution-the world's largest battery-is under construction nearby. Two cavernous steel tanks, each one 10 meters tall and 20 meters in diameter, will soon hold nearly four million liters of concentrated salt solutions, electrolytes that will be charged and discharged by 24,000 fuel cells in an adjacent building. At night this installation, known as a flow cell battery, will suck electricity from the grid and store the energy, which it will discharge during the day when power lines are strained. When blackouts strike-common in this tornado-prone region-the huge battery will keep the base humming for up to 24 hours.

This massive battery represents more than a backup power supply for an isolated military facility. It's a bold experiment in large-scale electricity storage on the power grid-the aging maze of interconnected power plants and transmission lines that cover the country. Today's grid operates with minimal storage, so at all times, electricity flows must exactly balance the power that's being consumed. Partial solutions are available in a new class of digital switches that more efficiently deliver electricity during crunch periods (see "A Smarter Power Grid ," TR, July/August 2001). But devices such as the Columbus flow cell, which is being built by the federally operated Tennessee Valley Authority and Swindon, England-based Regenesys Technologies, go one step further. By storing hours of electricity, flow cells offer, for the first time, the possibility of freeing the grid from the need to continuously balance production and consumption.

The implications of a newly flexible grid are immense. Sufficient storage capacity would relieve pressure to build new power plants and transmission lines, prevent regional blackouts, even speed the adoption of wind farms and solar panels by transforming intermittently produced power into steady reserves. Also, by dampening glitches and power spikes, the more flexible grid would provide the high-quality power needed for today's sensitive electronic equipment. Problems ranging from blackouts to the voltage fluctuations that cause chaos in high tech manufacturing sap an estimated $119 billion from the U.S. economy every year, says Kurt Yeager, CEO of the Electric Power Research Institute, a utility-funded R&D consortium in Palo Alto, CA. This hemorrhage is just one indicator that power grid fundamentals need rethinking, he adds. "The world as we know it can't continue. Prudent people would not wait for the lights to go out to do something about it. We've got to change the architecture of the grid," he says.

http://cache.technologyreview.com/articles/03/03/fairley0303.asp?p=1

[phantom power]

1. I remember reading that "flow-cell" article when it was published

I've often wondered about how scalable it is, in terms of things like cost and environmental impact. For instance, if I proposed this as a terawatt-hour class of grid storage solution for intermittent renewables (solar, wind), could the U.S. (or anybody else) actually do it without going bankrupt and/or unacceptable environmental impact?

[skids]

2. Yeah, "flow cells" is an old name for vanadium redox batteries.

It's a technology you'll be seeing more and more of. It has competition for stationary storage in the form of flywheels, but it will probably hold a major portion of the market despite that. In addition vanadium redox batteries have the vehicle sector, whereas flywheels won't achieve as much market penetration there -- they can handle the occasional earthquake but the abuse of in-vehicle use probably will make using them much more of a challange. Flow batteries just need some technical tweaks to reduce their weight ratio and they are much more robust for that purpose.

VRBs:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x28245

flywheels:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x29575

[gulfcoastliberal]

3. I knew someone on DU already wrote about this. Thanks for the links skids!

The flywheel is intriguing. No doubt about it, something must be done to shore up the grid.

[phantom power]

4. Cost per terawatt-hour

This Columbia installation costs (estimated) $25million, at $2000/kW. So, it's wattage is 12.5 mega-watts. They said it runs for 24 hours, so it's storage capacity is 300 megawatt-hours.

If I wanted to store a terawatt-hour, it would cost me $83 billion.

It would also require about 13 billion liters of whatever solutions they are using. I don't know what the environmental issues of those salt solutions are (if any), but that's how much of them you'd have lying around, per terawatt-hour.

[gulfcoastliberal]

5. Very expensive. But the electric utility association sez costs will come

down as demand for grid reliability and flexibility increases production. I agree re: unknown enviro consequences if they leak their solution. The flywheel contraption also sounds interesting & possibly less damaging in the link in skids post.

[phantom power]

6. It was actually less expensive than I thought it'd be.

These kinds of things usually end up costing trillions of dollars when you start talking about terawatts, or terawatt-hours. By comparison, $83 billion per terawatt hour is dirt cheap.

Aside from grid-balancing, I'm interested in storage solutions we'd require to implement large-scale wind power. Wind and solar only work well if you've got multiple terawatt-hours of storage to dedicate to windless or cloudy days. At $83billion per terawatt hour, I think we could actually afford it.

I do wonder about all those salt solutions. Probably no worse than the billions of liters of oil we schlep around.

[skids]

7. The cost scale isn't quite linear.

In these systems there are two components that can be scaled separately. The stack (more expensive) and the electrolyte volume (much less expensive)

So the energy capacity is cheaper to upgrade than the power capacity. In addition bigger stacks probably cost less per watt. FWIW.

The salt solution is vanadium or vanadium bromide. Not harmless, but not incredibly toxic either. (Naturally you don't want the positive tanks to mix with the negative tanks, that would cause a nasty chemical fire.)