What happened

Tuesday is looking like another good day for alternative energy stocks, with shares of fuel cell stars Plug Power (NASDAQ:PLUG) and Bloom Energy (NYSE:BE) rising 3% and 3.6%, respectively, in early trading as of 10:25 a.m. EDT. Elsewhere in the sector, Lithium Americas (NYSE:LAC), a company that is developing two projects for the production of the lithium metal that is integral to the functioning of rechargeable batteries for electric cars, is seeing its stock continue to rise -- up another 6.6% on top of yesterday's 16% gain.

The question is, why?

Glowing green arrow climbs on a stock screen

Image source: Getty Images.

So what

I challenge you to find any clearly good news regarding any of these three companies. No analysts have upgraded them, nor even tweaked their price targets higher. No earnings have been reported, nor are any expected. (All three companies, in fact, will next report earnings no sooner than November.)    

Which leaves us at a loss for what catalyst may be behind today's moves. Theoretically, I suppose, we could point to the finally stabilizing price of oil -- both Brent and WTI crude prices finally scored a sub-1% uptick in price today, after falling 12% from the end of last month. If you think of fuel cells and batteries as "alternatives" to oil, then stabilizing oil prices logically imply more pricing power in renewable fuels offered as an alternative to expensive and exhaustible oil supplies.

And of course, there's still that weekend report from Wood Mackenzie to consider -- the one that said electric cars are gaining popularity and could make up 40% of passenger cars sold annually by 2030. That could certainly explain the share price strength at Lithium Americas.

Now what

But if I'm being honest, here's what I really think is happening today:

Last week, for almost four straight days, investors sold new-wave tech stocks off en masse, worried that their relatively weak profits just didn't justify their sky-high prices. This week, the tech-heavy Nasdaq is turning around a bit, tech stocks are back in vogue, and it's a "risk-on" kind of a week. What we're seeing now is simply a shift in sentiment, and unprofitable alternative energy stocks like Plug, Bloom, and Lithium Americas are benefiting from the reprieve.

Enjoy it while it lasts.

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.