What happened

I know it's bad form to say "I told you so" -- but facts are facts.

And I did tell you Monday after shares of Bloom Energy (BE -4.12%) tumbled in morning trading that they would probably bounce back today, after the CEO of rival Plug Power (PLUG -4.42%) got a chance to talk up the hydrogen economy on Mad Money last night. Color me unsurprised, therefore, to see that Bloom Energy shares soared 7% in early trading today, and as of 11:30 a.m. EDT are still up by 3%. The broader market as measured by the S&P 500 index, meanwhile, is essentially flat.

Stock up glowing green arrow climbs on a stock screen

Image source: Getty Images.

So what

So what exactly happened to cause this? On Monday, as you will recall, Bloom Energy got caught up in a broad sell-off of energy stocks caused by the declining price of oil and rising pandemic concerns. Today, oil prices are bouncing back, which has helped revive Bloom Energy's stock price.

Helping even more, though, is the fact that Plug Power CEO Andrew Marsh went on CNBC last night to reassure investors that consumers, corporate customers, and perhaps even governments are beginning to warm up to hydrogen-powered fuel cells, and to assert that "the hydrogen industry is just beginning."  

Now what

Now, it's only natural to see Plug Power (up 4.1%) respond positively to that news. But I'd argue it was just as predictable that Bloom Energy, which like Plug Power both produces fuel cells and intends to produce hydrogen for fuel cells, would get a boost from Marsh's appearance as well. Whether their share prices can sustain this momentum, however, will depend on one key factor: Can they turn PR promises into renewable energy profits that investors can rely on?

This question remains to be answered.