As the saying goes: Slow and steady wins the race.

But when you're trying to impress Wall Street you better not be too slow, or your stock will be crushed in an instant. Ballard Power Systems (Nasdaq: BLDP) is finding that out today, when a 29% increase in revenue, to $15.3 million, and a 40% growth in fuel cell product sales still fell short of what investors wanted to see. More importantly, net loss increased to $10.2 million, from $6.6 million last year, despite a $3.3 million gain from an asset sale.

Growth should continue throughout the year, but investors should keep their eye on gross margins in the process. Gross margin increased just 1%, to 16%, this quarter and management is targeting 30% to 35% in the long term, so there are a lot of improvements that have to take place to get there.

Fuel cells are a growing technology, but the slow and steady race to profitability is taking longer than we might hope. And with General Electric (NYSE: GE) and United Technologies (NYSE: UTX) getting in the fuel cell game, Ballard better hope the industry grows quickly.

Cleaning up coal
FuelCell Energy
(Nasdaq: FCEL) is hoping to make a move into "clean coal" with a new $11.7 million cost share award from the Department of Energy. Right now, FuelCell can burn methane and natural gas as fuels, but coal would provide another abundant alternative.

Just like Ballard Power Systems, FuelCell has failed to reach profitability despite increasing sales over the past year.

I would avoid both fuel cell makers until they can prove they're a steady tortoise that's going to win this race and not one that isn't going to finish at all.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.