What happened

Are hydrogen fuel cell stocks the future of energy? Investors Wednesday seemed to have some doubts about that, as shares of Plug Power (PLUG 1.11%) plummeted by 9.8% and rival Bloom Energy (BE -0.81%) declined by 8%.

Meanwhile, stock in Nikola (NKLA -3.26%), which has plans to field a fleet of fuel cell-powered trucks, was down 6.3%.

3 red arrows going down and crashing through the floor

Image source: Getty Images.

So what

What was the catalyst to spark the declines? There was nothing obvious in the news today -- no analyst downgrades, no price target cuts, no downbeat announcements from the companies themselves.

Rather, this seems more of a long-term trend of waning investor interest in the fuel cell sector. Plug Power stock has been suffering for some time now due to concerns that its rapidly rising "gross billings" don't seem to be turning into actual GAAP revenue -- a fact that may have contributed to the company's announcement a couple of weeks ago that it will have to restate its financials. Similarly, stock Bloom has been trending lower ever since it reported a surprise fourth-quarter net loss last month.

And Nikola? In one respect, it's the odd man out in this story, because rather than building fuel cells itself, it simply plans to integrate them into its trucks. Problem is, the functionality of those trucks has been called into question (by the company itself). And on Tuesday, the competition in its niche intensified a bit when putative self-driving truck manufacturer TuSimple Holdings filed to go public in an IPO.

Now what

What would it take to perk up investors' interest in fuel cell stocks again? Some profits would help. In their entire history as publicly traded companies, none of these three companies has ever booked a profit, or even come close.

Problem is, analysts don't see much chance of any of these companies changing their stories on profits anytime soon. According to the most up-to-date estimates we have from the data crunchers at S&P Global Market Intelligence, Bloom won't report its first full-year profit before 2023 at the earliest, Plug not before 2024, and Nikola -- not until 2025.

Until they figure out a way to make money from this business, I'm afraid fuel cell stocks will remain at the mercy of investor sentiment and momentum investors alone.