For the ninth straight year, Platts ranked 250 of the world's top energy companies. Not surprisingly, the top 10 are all oil and gas companies. The list highlights some important trends for investors, however, and is worth considering in that respect.

The list
Platts evaluated the world's energy companies using four metrics: asset value, revenue, profit, and return on invested capital. The top 10 are listed here:

Rank

Company

1 ExxonMobil (NYSE: XOM)
2 Chevron (NYSE: CVX)
3 Gazprom
4 PetroChina (NYSE: PTR)
5 Total SA (NYSE: TOT)
6 Royal Dutch Shell (NYSE: RDS-A)
7 ConocoPhillips (NYSE: COP)
8 China Petroleum (NYSE: SNP)
9 Rosneft
10 LUKOIL

Source: Platts.

Though world demand for coal grew 7.6% in 2010, it wasn't enough for a single coal company to break the top 10. Demand for oil and gas grew 3.1% and 7.4%, respectively. As a result, ExxonMobil ranks first for the seventh straight year.

Notably, but expectedly, absent is BP (NYSE: BP). The company was ranked second last year and plummeted to 118th place because of the cost of last year's devastating Deepwater Horizon disaster.

Growth in Asia
Like everyone else, Platts analysts point to Asia as the region that is home to the biggest growth. But it's not population growth that propagates the Chinese energy boom; it is the country's increasing urbanization. Considered one of history's largest mass migrations, an estimated 16 million people will move into urban areas in China by 2020, likely creating an unprecedented demand for energy.

There are 70 Asian companies on the Platts list this year. Perhaps an indicator of the region's potential, the two ranked highest, PetroChina and China Petroleum, are not among the 20 fastest growing companies.

Parity in the global marketplace
This year's top 10 is the most globally diverse group, featuring three American, three Russian, two European and two Chinese companies. Just five years ago, the top 10 featured only two companies outside of the U.S. and Western Europe: PetroChina and Petrobras (NYSE: PBR). The Brazilian company ranked 12th on this year's list, falling from fourth place last year.

Russia made a particularly impressive showing this year. The country's national gas giant, Gazprom, ranked third overall, and there are now 15 Russian companies in the top 250, compared with only nine five years ago.

Foolish takeaway
Lists are everywhere these days, and when they come from reputable sources like trade magazines and industry journals, they often provide a great beginning for investment research. Keep tabs on the best of the best -- click here to add the companies above to My Watchlist.

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.

Motley Fool newsletter services have recommended buying shares of Total, Petroleo Brasileiro, and Chevron. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.