Best way to recharge netbook on a long plane ride?

In a couple of weeks I'll be on a very long overseas flight. I have a Lenovo Ideapad S10-3, and I should be able to get about 6 hours out of the battery. My flight is more than 12 hours long, and it doesn't look like my coach seat has a power port. I could buy and bring a spare battery but would like to avoid that if possible.

What can I do to keep from spending more than half of my flight with a dead netbook? Thanks much.

Some airlines have car-lighter sockets under the seats. Some have wall-plugs on the back of the seat in front of you. Things improve on new birds. But yeah, have multiple batteries if you gotta run it for a while. But have the plugs and the air/car charger just in case - although the plane might be 15V vs. 12V for the car.

You might be able to go to your airlines website and look at the inflight entertainment or technology entries (and the seat maps for the specific models/planes) to see what's what.