BP's (BP 0.13%) Statistical Review of World Energy shows the limited options that face the global energy system. With 2013's primary energy growth rate of 2.3% falling below its 10-year average, there are signs that the search for economical, emission-light energy is taking its toll. A diversified portfolio is the only way to help adjust the energy system we have inherited. 

Natural gas 
Turnaround plays are not only exciting, they can be very profitable. Chesapeake Energy (CHKA.Q) has been accumulating cash, and recently announced that non-core asset sales are expected to help decrease its net leverage by $3 billion with a limited impact on 2014 production. Basically, the company continues to rationalize its capex budget. From 2010 to 2013 Chesapeake's net cash used in investing activities has fallen from $8.5 billion to $3 billion.

BP's Statistical Energy Review notes that in 2013 only the U.S. saw above-average growth of natural gas consumption. Thanks to a growing distribution network, Chesapeake is right in the middle of the shale boom. It continues to develop unconventional plays like the Utica and Marcellus to reach its goal of producing 1 million barrels of oil equivalent, or BOE, per day. Natural gas is a relatively clean fuel, and the EPA's push to make America's utilities less carbon-intensive puts more wind in Chesapeake's sails.

Coal 
Our old friend coal is not painted in a very flattering light, but in 2013 it was the fastest growing fuel and reached its highest portion of primary energy production since 1970.

China's leader Xi Jinping stated that the nation needs an energy revolution to deal with pollution issues and supply challenges. This is not encouraging news for coal, as China contributed 67% of coal's demand growth in 2013. The upside is that other big Asian consumers like India are there to help pick up the slack. 

Not all coal is the same. Utilities can buy relatively clean, low-sulfur Powder River Basin coal from Cloud Peak Energy (CLD), or stick to more traditional dirty sources.  China and the U.S. are tiring of highly polluting coal, and Cloud Peak Energy is a critical part of the solution.

Cloud Peak Energy already has access to critical export facilities on the Pacific Coast. The company's 1.5% profit margin is slim, but its 18.1% gross margin and 6.3% EBIT margin give it room to breathe, while marginal coal producers are forced to reduce production.

Nuclear 
Global nuclear energy output grew by 0.9% in 2013. This is significant as it was the first increase since Fukushima rocked the world in 2011. Nuclear now accounts for its smallest percentage of global energy production since 1984.

In the midst of these difficulties, nuclear still has a strong future thanks to its military applications and baseload capabilities. Nuclear weapons are an important part of the nation's military, and escalating tensions continue to bring Asian nuclear abilities to the forefront. In addition to the security applications, nuclear energy provides a straightforward way to replicate coal's baseload generation without emissions.

Cameco (CCJ 0.16%) is the world's preeminent pure-play uranium miner. It has a host of high-quality mines and a small total debt-to-equity ratio of 0.25. Its margins are low as the industry is still recovering from Fukushima, but this has allowed Cameco to buy up assets from potentially dangerous competitors. The good news is that its gross margin of 35.2% lets it sit back and watch the market recover.

Renewables
In 2013 Renewable Energy used in power generation grew 16.3%, contributing a total of 5.3% of global power generation. SunPower (SPWR -1.02%) is on the right side of this growing industry. Its high-efficiency solar panels and low degradation rate let its solar panels produce 75% more energy than its competitors on a given rooftop over 25 years.

SunPower's distributed generation operations still face risks from unstable government policies, but its push to commercialize energy storage solutions in Australia will eventually help to decrease its dependency on retail feed-in-tariffs. Its profit margin of 5.4% shows that renewables are already in the black.

Final thoughts
The 20th century was dominated by fossil fuels. Fossil fuels continue to play a significant role, but a move to emission-light generation is pushing SunPower, Chesapeake, Cloud Peak Energy, and Cameco to the forefront of the energy industry.