Toyota's FCV Concept is a preview of the company's first fuel-cell car, expected to arrive at dealers in 2015. Photo credit: Toyota

What's the deal with hydrogen cars?

"Hydrogen cars" are vehicles powered by fuel cells. Fuel cells chemically convert the energy in hydrogen to electricity. A fuel cell -- plus a tank of hydrogen -- can replace a big bulky battery packs in an electric car.

Toyota (NYSE:TM), Honda (NYSE:HMC), and Hyundai (OTC:HYMTF) all showed off new fuel-cell vehicles earlier this month -- and they, along with several other big names, have promised to put them into production over the next few years. 

Why does it seem that automakers are suddenly pushing fuel cells instead of battery-electric cars? In this video, Fool contributor John Rosevear looks as the advantages (and disadvantages) of fuel cells as compared to batteries, and explains what will have to happen before American drivers can move to a hydrogen-powered future.