Wednesday, December 16, 2009

Electric cars provide grid storage in two different ways

Changes in technology create problems, and solve them.

The electric car, interestingly, could inadvertently resolve one of the troubling issues in Hawai'i's utility-scale energy picture—in two different ways.

(Image: The all-electric Tesla Roadster. Credit: Tesla Motors.)

Both of them address the issue—important in Hawai'i—of how to blend intermittent power sources into a grid that has a need for reliable, constant energy.

Electric vehicles are viewed by many as the future of personal transportation. Even if fueled from the oil-fired utility's plug, they use far less fossil fuel than a gas-powered car. In large part, that's because big utility-scale powerplants are dramatically more efficient than hundreds of little car engines.

Many visionaries have posited an energy future in which these electric cars serve the community in another way. While they are plugged in, a smart utility grid might draw power from the battery cars to make up for temporary shortages in generation capacity.

You could set your car to always keep enough of a charge for your daily driving, but to allow the utility access to some of your power. You'd get paid for this, of course.

This works nicely if there's a big intermittent utility power source. Example: If the wind stops blowing, the utility can turn to electric cars to keep the grid up in the minutes or hours it takes to bring other generators online.

That's emergency energy storage.

But there's another role for electric cars.

What happens to those vehicle's big battery packs 8 or 10 years and a couple of thousand charges down the road, when they won't hold a full charge any more, and you want to replace them.

They don't need to be recycled yet. They're still capable of holding 80 percent of a charge, and may still handle thousands more recharge cycles. They're just too weak to run your car as far as you need to go.

Those old batteries could be converted to direct utility use. They could become massive battery banks that would, for example, store photovoltaic power for use when the sun isn't shining.

Project Better Place, which has been discussing an electric car future for Hawai'i, said one of their visions for older batteries is for this application.

Now Nissan is suggesting a similar use.

Each company—Better Place and Nissan—has developed a business model to ease the concerns of motorists about battery life cycle.

Better Place would retain ownership of the battery packs, and their system would even allow you to accomplish a quick charge by simply swapping depleted batteries for a fully charged battery pack. Nissan is proposing a battery lease system for its LEAF car, with the batteries available as utility battery banks when they come off lease.

So, waiting in the wings with the electric vehicle future, is one resolution to the problem of intermittent power supply.

This isn't pie in the sky stuff. Some utilities already have battery farms. And others are planning them. Some battery makers are already converting their automotive lithium-ion batteries to utility storage configurations.

The government is putting quite a bit of energy (sorry!) into the concept of utility scale battery storage: This one, from the Sandia National Laboratories, is already couple of years old.

© Jan TenBruggencate 2009


zzzzzz said...

I thought this was one of the primary rationales for Better Place, and part of their business model. They would buy power cheap from guys like windfarms when they produced more than demand, and sell it back to HECO at a higher price when HECO generators can't meet demand, reducing the amount of generation capacity HECO needs to install.

Jan T said...

As I understand the Better Place folks, they argue that the utility can take the power out of the batteries while they're in the cars, if you're hooked up to the charger. The point here is that even after the batteries have lived out their usefulness for automotive applications, they can still meet utility needs by becoming part of utility battery farms.