Building Better Batteries

Though there are plenty of ways to create electricity from renewable sources, one of the problems with making them viable is making the power available whenever we need it.

Solar is great, during a bright, sunny day, but all those panels don’t do much good at night. And what are you going to do with all those wind turbines during a windless spell? Even if your solar parks and wind farms can put out more power than needed at peak output, there aren’t many options for storing the extra juice for a windless, rainy day.

Sure, there are batteries, but these aren’t very good for holding on power on an industrial scale. Plus they’re expensive and often packed full of some serious pollutants.

But in the past week, I’ve heard of two really cools ideas for doing exactly that: banking renewable energy. The first (covered in nice piece in the NYTimes Magazine by Clive Thompson) is the Iowa Stored Energy Park, a still-in-development project that will use wind turbines to generate electricity, which in turn powers a series of powerful air compressors. These force air down into the earth, into what is called a compressed air energy storage system. Think of it like a giant underground balloon.

When the wind dies down, simply let the air out of the balloon; any kid can tell you what happens when you let go of an inflated, untied balloon, right? But instead of propelling a little piece of latex across the room, the kinetic energy of air escaping from a CAES is heated, and used to power a turbine. The project sponsors say the stored air can power a pair of 134-megawatt turbines, generating enough electricity for 80,000 homes, anytime it’s needed.

The other idea is just as cool, but works with solar power. Solar cells can seem kind of mystical – just shine a light on that funky black panel and out comes electricity. It almost seems like producing power from nothing.

But sunlight isn’t just light, it’s heat. Really, what is the sun, but a giant exploding ball of hydrogen, right?

So several innovative companies are pushing solar thermal systems, which use lenses and mirrors to focus sunlight into super-hot beams of energy. There are a few different concepts in play here; one uses that energy to heat up a huge tank of molten salt, which can retain its temperature for hours. Another idea is to heat up miles of black piping, filled with a special fluid, again designed to retain that heat energy.

Both plans then take that stored heat energy to boil water into steam, which is used to power a steam turbine and produce electricity, whenever it is needed.

It’s like those gag gifts you can buy in Florida -- a can of genuine Florida sunshine -- except these projects are no joke; they really can store wind and solar power, and are no joke.

Bad Corporate Citizen

I admit it. I fell for the spin.

Last year I posted an item praising Wal-Mart Stores Inc. for its green strategy. The retailer has built a few stores using all sorts of energy-saving designs, and is pushing suppliers to use eco-friendly packaging, and I went out on a limb to say the company was demonstrating a long-term vision tied to the bottom line, exactly the kind of business decision that can make alt-energy policies viable.

Turns out it was mostly hype.

At the Wall Street Journal’s ECO:nomics conference last month, Wal-Mart’s CEO Lee Scott Jr. all but admitted that the whole point of his company’s green push is mostly hype. “We are not green,” he said.

And despite its efforts to use alt-energy at a few stores, the company’s overall carbon emissions continue to climb, and Mr. Scott said that is unlikely to change since growing the company is his top priority, and other factors, like alternative energy, promoting the environment, saving the world, etc., are less important.

The best part: one conference attendee asked him when, if ever, Wal-Mart might meet its stated goal of eliminating waste and using only renewable energy. “I haven’t a clue,” Mr. Scott answered.

At least he was being honest.

As for me, I guess I can go back to trusting my gut instincts when multinational corporations try to claim they are doing good.