Mon February 7, 2011
Smart Grid

Battery facility could lead to a greener grid

Managing the power grid is a balancing act. As we flip on our coffee makers and turn on hairdryers, the grid is reacting, breathing harder, to keep up with our demand. A facility in upstate New York is using battery power to try to make walking that tight rope more efficient.

The energy experiment is playing out behind the smokestacks of an old brick coal power plant in Johnson City, N.Y. on a small, snowy lot.

The storage facility is contained in a row of shipping containers elevated on stilts. John Zahurancik, who's overseeing deployment of the project for AES Energy Storage says the trailers contain racks of batteries - about 80,000 of them.

So far this story is pretty easy to understand: the power grid needs to stay balanced to meet our energy needs, batteries store power.  Well here's where we get to the physics lesson. 

Our existing power system uses what's called "AC current." AC is always switching directions, going back and forth. And that back and forth has to be kept steady, or else things break. 

In the past, keeping the rate of that back and forth regular has been managed with coal or gas in plants, ramping up or spinning down to balance the grid.  But Zahurancik's facility could change that with their batteries, making the whole process a little greener.

There is waste involved in using batteries to balance the grid (though on a cold winter day, the excess heat radiating from the batteries in the storage containers is welcome). But it's much less waste than would be created by the alternatives.

That's according to Jonathan Silver, from the Department of Energy (DOE). The DOE helped to finance the Johnson City plant, as part of an effort to green not an individual coal power plant, but rather the energy delivery system itself.

"[Batteries are] much cleaner. In fact this technology results in savings of about 70 percent of carbon dioxide emissions," says Silver.

The DOE's backing is important because, despite its promise, this technology is still in its infancy in the grid.

Research on battery technology has been going on for consumer electronics and electric cars for years. But as batteries got cheaper and more efficient, people who worked on the grid started to realize that batteries could be a solution for some of their problems too. As a result, over a hundred companies now have storage projects underway--though many have bet their money on other types of energy storage, like using flywheels or air compressed in caves.

But again, we are very early stages of understanding battery storage.  So the question that UCLA grid researcher Rajit Gadh poses, is a crucial one:

"Is it going to spread, and is it going to become a standard way of storing energy?"

Gadh believes the answer is "yes." 

Here's why: Just like there aren't outlets for electric cars in all our garages, there isn't the infrastructure in place to plug all the wind turbines and solar panels we want into the grid.

For now, balancing the grid is mostly about tweaking the output of a couple of power plants to keep up with people turning their lights on and off. But in the future, utilities will have to cope with more finicky solar and wind generators, whose output changes as the wind blows, or as clouds cover the sun.

Gadh says, the real unknown - but exciting - possibilities for batteries on the grid will be in long term storage.  That means not just balancing the grid minute-to-minute, but storing energy from wind turbines or gas power plants to use later.

"At night, typically, utilities have a lot more energy available. We all know on a hot summer afternoon when temperatures hit 100 degrees, that's when energy prices start to rise. You can take very very cheap energy at night, and store the energy in these batteries across the country," Gadh says.

Zahurancik agrees there's long term storage potential - he's studying that too for AES.

"In the future ... the power system itself has to get smarter, more responsive more flexible," he says.

For now the technology is in its infancy. But you have to start somewhere. Zahurancik points out that just a few years ago those 80,000 batteries and shipping containers were nothing more than a big idea and a series of diagrams.