Apparently impressed with the company’s plans to expand into new markets, Zacks upgraded Plug Power Inc (NASDAQ:PLUG) from Neutral to Outperform today, setting a price target of $7.90 compared to the current $7.16 (h/t Stephan Byrd at Ticker Report).

Plug Power

Technically, Plug Power Inc (NASDAQ:PLUG) has seen its stock price jump more than 4000% over the last six months, most of that since the beginning of December, making it far and away the best performer on the NASDAQ. Maybe a more useful way to look at it is that the company is a former penny stock (literally less than a quarter per stock this time last year) that has suddenly moved into the big leagues. Now the question is whether they can build on that success, or whether Power Plug will slide back as far as its come.

Plug Power’s main business is forklift fuel cells

The company’s main business, at least for now, is building fuel cells for forklifts. CEO Andrew Marsh has explained that the company has no intention of stopping there, but it was a good entry point because of the lack of competition. The material handling sector just needed better forklifts, and providing them (along with the fuel cells) was the best way to start bringing in revenues.

Plans to expand sound reasonable (but they usually do)

Now he says that Plug Power Inc (NASDAQ:PLUG) will expand, and his choice of targets sound equally practical. Refrigerated delivery trucks, for example, often face noise pollution regulations that prevent them from idling for too long (the diesel engine keeps the refrigerators running, and diesel engines aren’t meant to be turned on and off all the time anyway). If he can create a better alternative, Marsh could suddenly have another strong revenue stream. It’s nowhere near as flashy as Tesla Motors Inc (NASDAQ:TSLA)’s high end electric sedans, but there’s no shortage of delivery trucks out there.

The other idea is to start building fuel cells for airport support vehicles, and again the suggestion sounds like a good fit. These vehicles don’t need to go especially fast or accelerate rapidly, and airlines are particularly sensitive to cost control. If Marsh can convince the airline industry that his vehicles have significantly lower lifetime costs, giving their margins even a small boost, he should get plenty of business.

But these are the best case scenarios, and it’s not hard to find CEOs with plans that sound good. Citron Research has called Plug Power Inc (NASDAQ:PLUG) a ‘casino stock’ with weak fundamentals that will eventually return to its sub-$1 stock price.