Savvy investors should keep at least 12 percent of their portfolios in fossil fuels, says Ken Fisher.

“In this country 89 percent of electricity comes from three fuel sources: coal, natural gas and nuclear fission,” Fisher writes in Forbes.

“If you want your air conditioner to work in 2014, you'd better hope that more fossil fuel plants get built.”

Among U.S. firms producing petroleum and natural gas, Fisher recommends Apache, Chevron, Hess, and Marathon Oil.

“These are all high-quality firms with balance sheets and cash flows … quite able to withstand the volatility in energy prices,” Fisher says.

“I like Apache's growth potential overseas and in natural gas, Chevron's mass and class, Hess' portfolio and projects, and Marathon's over-the-top cheapness.”

Fisher’s foreign favorite is Spanish firm Repsol, which holds a lot of assets in the Americas.

“A common criticism of Repsol is that much of its operations are in politically unstable parts of Latin America such as Argentina,” Fisher notes.

“I'm not as bothered as most investors by the politics of that continent.

“With increased wealth comes a bigger middle class and more political stability.”

The United States plans to call on the Group of 20 to eliminate fossil fuel subsidies in five years and increase oil market transparency when the group meets at the end of the month, Reuters reports.

The United States argues that fuel subsidies distort oil and product markets and artificially raise fuel demand.