Nothing will kill the dreams of a fledgling business quicker than crippling debt. In certain industries, energy being one of them, it's almost impossible to operate without borrowing, given the intense capital investments required to grow your business.

That reality makes the three companies below all the more impressive. And while zero debt doesn't guarantee future returns, it sure makes for a compelling start to your research.

Bolt Technology (Nasdaq: BOLT)
Bolt Technology specializes in marine exploration equipment. You know all of the cables, connectors, hydrophones, and undersea robots that energy companies need to map the seafloor? That's what Bolt makes.

The company had a strong fiscal 2011, recording sales of $38.8 million and earnings per share of $0.65 for the year that ended last June 30. Both numbers are an improvement on 2010 but have yet to match results from 2009.

I like two things specifically about this opportunity. First, while customers are very closely tied to the oil and gas industry, last year's acquisition of SeaBotix gives Bolt a customer list that also includes the defense industry, state and local governments, and fire and rescue squads. The more diverse your customer list, the better. Second, as deepwater drilling increases, Bolt is a company that is only going to get more relevant.

C&J Energy Services (NYSE: CJES)
C&J Energy Services is a hydraulic fracturing company. Its equipment does the fracturing, the high-pressure pumping, the whole nine yards. As it operates mostly in Texas, C&J's customers include big names in the U.S. production game: Anadarko, Chesapeake Energy, Shell, and so on.

The company currently operates six hydraulic fracturing fleets and expects to bring that total to nine by the end of 2012. The planned production cuts for the gas drilling industry shouldn't hurt C&J either, as all of its rigs are in oil- and liquids-rich plays right now.

C&J reported a big jump in net income for 2011: $162 million compared to $32.3 million in 2010. Earnings per share came in at $3.19, compared to $0.67 in 2010.

FX Energy (Nasdaq: FXEN)
Unlike most U.S. independents, FX Energy's prized assets are in Poland, of all places. The company produces solely gas there, selling it on the European market for about $10 per million cubic feet -- much more than the stuff is worth here. Conversely, FX Energy only produces oil from its U.S. assets, located in the Bakken shale.

Production in Poland has increased from 10 MMCFE per day in 2010 to 14 MMCFE per day so far in 2012, and the company aims to increase that further to 17 MMCFE by the third quarter. Production in the Bakken is in the early stages. FX Energy is testing one well, with plans to drill two vertical wells next month. It will also drill a 4,000-foot lateral on another well that was drilled vertically last year.

Foolish takeaway
A little debt can go a long way, and it is not always a bad thing. However, it can also significantly derail management's plan for the future. Debt-free companies are rare, but they exist, and quite often are worth searching for.

Fool contributor Aimee Duffy doesn't own shares of the companies mentioned in this article. If you have the energy, check out what she's keeping an eye on by following her on Twitter, where she goes by @TMFDuffy.

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