The last five years have not been kind to Plug Power (PLUG -5.25%). The hydrogen fuel-cell company was trading at about $10 a share in 2014, but today is trading between $1-$2 per share.

Of course, that kind of a big price drop might mean that the stock is ripe to outperform. Or it might mean that the stock market has realized the company is going nowhere fast. Could Plug Power turn things around and give investors a juicy payday? Even to the tune of a cool million dollars? Let's dig deeper to find out.

Check out the latest Plug Power earnings call transcript.

A man drives a forklift in a warehouse

Top fuel cell company Plug Power has had its greatest success with industrial equipment. Image source: Getty Images.

Stuck in a niche

Once upon a time -- like, 10 years ago -- hydrogen fuel cells were seen as a leading contender for mass-producing green energy vehicles. Companies like Plug Power and Ballard Power Systems (BLDP -2.23%) have turned that potential into reality -- kind of. 

While fuel-cell vehicles do exist today, most of the fuel cells made by Plug Power and Ballard are used in warehouses and airplane hangars, not on highways. Fuel cell-powered forklifts make up the bulk of these. That's because fuel cells can be recharged much more quickly than batteries, so they make an attractive alternative for a piece of equipment that can cause big bottlenecks every time it's offline for a recharge.

But Plug Power and Ballard don't want to be stuck in this niche market forever. Both have been working tirelessly to break into the broader vehicle market, particularly larger vehicles like delivery vans, buses, and light rail systems. If Plug Power could become a major player in this space, its share price could skyrocket and possibly even turn a modest investment into $1 million.

Full of potential

You may have heard Cyril Connolly's famous phrase, "Whom the gods wish to destroy, they first call promising." Although fuel cells did -- and do -- hold a lot of promise as a green fuel source, they have been utterly eclipsed by batteries in the transportation market. According to Information Trends, there were 6,500 fuel-cell vehicles on the road worldwide in 2017. But the International Energy Agency estimates there were about 3.1 million electric vehicles. And that was before Tesla (TSLA 1.50%) ramped up production of its Model 3. 

In spite of this, Plug Power claims that its fuel cells are more efficient than batteries, at least in forklifts. But the reasons it cites don't have anything to do with superior performance. Instead, the company states that fuel cells reduce the need for "time-costly battery changes and energy-consuming battery charges," as well as "progressive battery droop" as batteries age. But Plug Power only touts a 5% to 6% increase in productivity as a result, which doesn't seem significant enough to allow fuel cells to break batteries' stranglehold.

Indeed, the biggest current advantage held by fuel-cell vehicles over battery-powered ones is the difference in the amount of time it takes to refuel/recharge. It takes about five minutes to refill a fuel-cell vehicle, in a process similar to filling up at the gas station. On the other hand, even at a Tesla Supercharger, fully charging an electric-vehicle battery takes more than an hour. 

The trouble for fuel cells is that the vast majority of drivers don't need to rapidly refuel their vehicles on a regular basis, meaning that for many drivers, the primary selling point of a fuel-cell vehicle over a battery powered one is moot.

Down the drain

Another point against Plug Power's ability to make its investors millionaires is that it hasn't been particularly effective at making money, even in the niche market in which it has a strong presence. 

Plug Power hasn't turned an annual profit -- not once! -- in the 20 years of its existence. Currently, it's projecting strong revenue growth in 2019, but it doesn't seem to be turning that revenue into profits. Management is forecasting positive adjusted EBITDA in 2019 as well, but adjusted EBITDA isn't the same as profit, which means the company may post a 21st year of GAAP net losses in 2019. 

If the company can't even turn a profit on its products and services that it's already ramped up, it seems like pie in the sky to assume it will somehow be able to make a new, unproven technology that isn't operating at scale pay off for its investors, if it even manages to produce such a thing. 

Never say never

Technological innovation is a funny thing. Disruptive new products can emerge out of nowhere and quickly rise to become powerhouse brands, making millions for investors who get in on the ground floor. So I can't say with 100% certainty that Plug Power won't happen upon such a miracle cure for its corporate woes and turn itself around.

But given the hurdles fuel-cell technology currently faces in mass adoption and Plug Power's poor performance to date even within a niche it knows well, it's very unlikely that Plug Power is a millionaire-maker stock. In fact, to date, it isn't even a dollar-maker stock. For green-vehicle enthusiasts, there are better opportunities elsewhere.