) -- If you're looking for energy companies to add to your portfolio, oil majors like

Exxon Mobil

(XOM) - Get Report





(CVX) - Get Report

tend to come to mind first. But although these picks are indeed some of the biggest corporations in the world by market cap, there are plenty of tiny energy stocks out there worth your cash.

In fact, if you look outside of conventional crude powerhouses there are a number of

penny stocks

with big profit potential -- including some with a focus on nuclear energy and uranium.

Related Article: How to Invest in Nuclear Energy via ETFs

Here are four of my favorite energy penny stocks to buy right now. All focus on uranium and the nuclear power industry.

Denison Mines

Denison Mines

(DNN) - Get Report

is engaged in the acquisition, exploration and development of uranium-bearing properties. The company also extracts, processes, sells and reclaims uranium. Year to date, this penny stock has jumped an incredible 145.7%, compared with a gain of 5.6% for the

Dow Jones Industrial Average

. Last quarter, DNN posted a difference of six cents from its actual quarterly earnings to its original earnings estimate. Trading at $3.08, DNN has a yearly stock range of $1.08 to $3.31.

Related Article: 5 Bargain Stocks Below $5

Uranerz Energy Corp.

Uranerz Energy Corp.


is also involved with the acquisition, development and development of uranium properties. The company mainly operates in Texas, Wyoming and Saskatchewan, Canada. Since January, URZ stock has gained 204.6%, compared with much smaller gains by the broader markets. Uranerz may have a market cap of just $255 million, but the penny stock does offer great potential profits. URZ is close to its 52-week high of $4.13, as it currently trades at $4.00.

Uranium Resources I

Headquartered in Texas,

Uranium Resources I


is a uranium exploration, mine development and production company. URRE is the biggest gainer on this list, as the stock has jumped 374% since January. In fact, since September the uranium developer has gained 462%! URRE may be the best buy on this list, with its inexpensive stock price of just $3.65. Lastly, the stock is trading very close to its 52-week high of $3.71.

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Ur-Energy Inc.

Ur-Energy Inc.

(URG) - Get Report

is engaged in the identification, acquisition, evaluation, exploration and development of uranium in Canada and the United States. Year to date, URG stock is up 175%, and it's up 154% since the start of September. Fittingly, URG rounds out the list as another stock that is approaching its 52-week high. Currently trading at $2.10, URG stock is just eight cents below its highest mark of the year.

As of this writing, Louis Navellier did not own a position in any of the stocks named here.

One of Wall Street's renowned growth investors, Louis Navellier is the editor of four investing newsletters: Emerging Growth (formerly known as MPT Review), Blue Chip Growth, Quantum Growth and Global Growth. His longest-running publication, Emerging Growth, has a track record of beating the market nearly 3 to 1. Navellier is the author of a BusinessWeek bestseller, "The Little Book That Makes You Rich," and the chairman and founder of Navellier & Associates, Inc.