Before I get started with the focus of today’s Friday File, a green energy stock, I wanted to give you a quick bonus idea: You might have noticed that I wrote about Matt Badiali’s teasting of Denbury Resources yesterday, the oil stock that’s using CO2 injection to boost production, but he also teased a couple other ideas in that letter.

One of those ideas was for another oil services stock, one that makes the “secret ammunition” for extracting oil from shale fields. In this case he wasn’t talking about CO2 injection (that was the “magic drug”), but about proppants. These are little balls, essentially, that are injected in the wells as they fracture the shale, helping to hold open space so more oil can be extracted (at least, that’s my “I don’t understand this stuff” explanation).

And Badiali was kind enough to include some patent numbers in this tease (7,615,172… 7,387,752… 7,255,815… 7,119,039… 7,036,591… 5,188,175), so I can tell you that this proppant maker is the dominant producer of one particular kind of proppant, the ceramic variety: Carbo Ceramics (CRR).

I haven’t had a chance to look at this one very carefully yet, but it is a fairly low-profile, billion dollar company, and they are profitable and expected to grow earnings — the forward PE is about 17, the PEG ratio (price/estimated earnings/future growth) of about 1.3, so not terribly expensive on its face. Then again, their last earnings report came in worse than the Street expected, and there is a large short position (almost 20% of the float). The stock bounced back fast from the crash, doubling since last March, and despite a dip over the last couple months the shares are still within $10 or so of all-time highs. No debt, and decent margins, but I don’t know anything about the fundamentals of the business or the competitors — and particularly, how essential their product is and whether other non-ceramic proppants perform well in comparison.

So that’s a quickie for your consideration, just thought you’d want to know.

Today I want to take a look at another green energy teaser for the Friday File — in part because the “green” investing stuff seems to be heating up again after a good hiatus when a lot of these capital-intensive projects took a hit during the market crash (and the oil crash), and in part because it sounded ...