Gasoline inventories dropped below their five-year average and are now 6% below last year's average, according to Joseph Dancy, an adjunct professor at Southern Methodist University, in an essay published in Barron's this weekend.

This means the outlook for investing in energy remains good, Dancy believes, as demand for gasoline will grow 2% with little supply relief in sight. Particularly the lack of new refinery capacity means positive growth prospects for a company like Matrix Service Company (NASDAQ: MTRX) that specializes in repair and maintenance services to the refining, distribution and pipelines sectors.

Dancy wrote the supply and demand balance for energy could mean a sharp escalation of energy prices. Mexico's Cantarell field's output, the second largest in the world as measured by output, declined 17% in March from year-earlier levels, while offset by new production increases at a nearby field, total crude production from Mexico is down 5%. In addition, Venezuela production should get hit at some point as Chavez has taken control of exploring for and producing energy away from the foreign experts. And Nigeria, who sends 1 million barrels per day to the US, is also in a politically tenuous situation.

Add to this, the huge swing producer, Saudi Arabia, announced that is will no longer increase production after 2009, which might indicate the nature of its oil reserves.

In addition to Matrix, Arena Resources Inc (NYSE: ARD), OMNI Energy Services Corporation (NASDAQ: OMNI), Pioneer Drilling Company (AMEX: PDC), Natural Gas Services Group Inc (AMEX: NGS) were mentioned as attractive investment ideas.