A Green Challenge: Make Renewables Reliable Bringing renewable energies like wind and solar power onto the electric grid is the first step toward making the grid both green and smart, but engineers and power companies must also find solutions to the challenges of renewable energies, which don't produce consistent, reliable power.

A Green Challenge: Make Renewables Reliable

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From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.


And I'm Robert Siegel. We're featuring stories this week about something that most of us use every day but don't think much about: the electricity grid. It's outdated and ill-prepared for the future. The grid is one of the most complex of human creations. Engineers have to keep all the electrons in the grid in a delicate balance - not too many, not too few. But adding lots of new power from wind and solar energy could upset that balance.

NPR's Christopher Joyce has this story on some possible solutions.

CHRISTOPHER JOYCE: When you make electricity, it has to be used by a toaster, table saw, a light bulb - whatever. It's got to go somewhere right away. So grid operators - they're out there right now watching the grid on their computers - keep their hands on the spigot.

But if you get a sizzling day in July, people need more electricity, and operators have to order it up from a power plant somewhere. A balmy Christmas day in New York, and they tell power plants to turn off. Stopping and starting big coal and nuclear power plants is inefficient. It can also play heck with the frequency of the electricity on the grid. It's supposed to hover around 60 hertz. Now if you add a bunch of wind energy, turbines and solar power plants to the mix, it makes it even harder to even out the flow.

Dr. IMRE GYUK (Manager, Energy Storage Program, Department of Energy): I am Imre Gyuk, and I manage the energy storage program here at the Department of Energy.

JOYCE: Gyuk notes that sometimes there's no wind and sometimes there's no sunshine.

Dr. GYUK: You have the fluctuations not only from the consumer, you also it have from the generation.

JOYCE: Intermittent power like this bugs grid operators. They got a taste of it in February 2008. One day, the wind just died in the big patch of Texas. Electricity from wind turbines plummeted at a time when other power sources were low and consumer demand had spiked. Operators had to scramble to find substitute power.

Dr. GYUK: The disturbance was felt throughout the United States, all the way up into Manitoba. I mean, people could see the grid shaking, so to speak.

JOYCE: Now the Obama administration wants to get wind and solar power up to where it's contributing maybe 20 or 30 percent of our electricity. And that's going to play havoc with the grid, unless there's a way to store some of that power when there's a surplus and then when retrieve it when it's needed. And Gyuk says you can.

Dr. GYUK: You put a large number of small batteries around a neighborhood, just like the neighborhood transformers, just the little green box that's innocuous.

JOYCE: Small meaning the size of a battery in a hybrid car, for example. In fact, DOE and utilities like American Electric Power actually think they can take batteries made for plug-in hybrids, even used batteries, and hook them up to the grid. When there's surplus power, say, an especially windy day, you charge the batteries and save that energy for a rainy or a windless day.

Dr. GYUK: If you have these storage units sitting throughout the community, then you can simply withdraw for a half an hour's worth of storage to make up for the wind that isn't there.

JOYCE: Half an hour is all grid operators really need to keep the grid running smoothly. The Department of Energy is plowing over $600 million from the government stimulus package into storage technologies. Besides batteries, there's something called a flywheel, a spinning metal wheel.

Mr. GENE HUNT (Vice President, Beacon Power): It spins around a kind of axel. It's a rotor, in fact.

JOYCE: Gene Hunt, vice president of Beacon Power in Massachusetts, says one of their flywheels spins at 16,000 revolutions a minute.

Mr. HUNT: And it's in a high pressure vacuum, which reduces the friction to almost nothing. And it floats on magnetic bearings, and it essentially levitates the rim itself as it floats around in the vacuum.

JOYCE: And what it's doing is storing rotational energy.

Mr. HUNT: It's the same principle as that of a potter's wheel. A potter's wheel, it's powered by the human foot pumping the pedal up and down. It turns this wheel. And then when you take your foot away, it continues to spin. It's the - it's using the energy that's stored in there.

JOYCE: Beacon is building flywheel farms, if you will, that can provide electricity in short bursts when operators need to top up the grid. There's enough energy in one bank of flywheels to power 40,000 homes for 15 minutes.

Mr. KARL LEWIS (Chief Strategy Officer, GridPoint): I'm Karl Lewis. I'm chief strategy officer at GridPoint. This is our hardware lab.

JOYCE: GridPoint designs storage devices and software to hook them up to the grid in its Virginia laboratory. One of their inventions is an electricity storage device you can put in your basement. The customer can store extra electricity and the utility can get it back when it needs it.

Mr. LEWIS: So the utility can see, you know, hundreds of thousands of units in aggregate and treat them like a virtual power plant.

JOYCE: And so the utility will know at any one time how much energy is out there stored in all these devices and how much you can draw for how long, whenever it needs to.

Mr. LEWIS: Exactly.

JOYCE: And this partnership might also extend to your electric car.

Mr. LEWIS: As a car wanders around the grid, we know where the car is, where it's plugged in, how much energy it needs. And what happens is that car is now becoming a smart charging asset, available both to the consumer and the utilities using it to manage the peaks in the grid to decrease our generation costs.

JOYCE: Which raises a question.

People ever say to you, we don't want you to know everything about what we're doing with our power?

Mr. LEWIS: All these programs are what are called opt-in programs. The customer is opted in or participated in the program because they're getting something back.

JOYCE: What they're getting, according to these new grid designers, will be a more efficient grid and one with more electrons from wind and solar generators, and maybe after all the improvements are paid for, cheaper utility bills.

Christopher Joyce, NPR News.

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