Renewable energy sources like solar and wind power are growing fast, gaining market share in the world's energy markets. Companies that focus just on renewable power are easy to find, but they aren't the only way to gain exposure to this trend. In fact, we are also a long way from a world powered solely by renewables, with current power options deeply entrenched and supported by years of strong demand ahead of them. This will provide existing energy suppliers ample room to shift with the times. Which is why it shouldn't be too surprising to find out that old-school energy companies like NextEra Energy, Inc. (NYSE:NEE), Xcel Energy Inc. (NASDAQ:XEL), and The AES Corporation (NYSE:AES) are quickly bringing renewables into their businesses.

1. Among the largest

NextEra Energy owns Florida Power & Light, a traditional regulated utility based in Florida that happens to be the largest electric utility in the United States. However, it also operates a business called NextEra Energy Resources. This division of the company owns a renewable-merchant-power business that is one of the largest wind- and solar-power companies in the world, with 20 gigawatts of power capacity.

Torso of a man holding a hard hat with an image of power lines behind him

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Roughly 70% of that capacity is wind, 11% solar, and 14% nuclear, with the rest spread across natural gas and other fuels. NextEra has long-term plans to build another 40 gigawatts of renewable generation, with a current goal of spending as much as $25 billion on renewables between 2017 and 2020. The stock isn't cheap, trading with a relatively low yield of 2.6% and a relatively high (compared to peers) forward P/E of 22. However, it is expecting capital spending to push earnings up around 11% to 12% a year and dividends higher by 12% to 14% annually, driven by letting its low payout ratio increase. For dividend-growth investors interested in renewable power, NextEra is worth a closer look.

2. It's windy in the Midwest

Xcel Energy is an electric and natural gas company that operates in eight western and midwestern states. In 2005, it generated just 5% of its electricity from wind and solar power. Today that number is up to 23%. The goal is to reach 45% by 2030, with 3.6 gigawatts of renewable construction in the works today. Add in the roughly 13% the company generates from nuclear power, and by 2030, clean energy will account for nearly 60% of Xcel's generating capacity. Wind, which is plentiful in its operating areas, is a key contributor to these totals.

NEE Dividend Per Share (Annual) Chart

NEE Dividend Per Share (Annual) data by YCharts.

The spending to get from here to there, while also supporting its traditional operations, is expected to push earnings higher by 5% to 6% a year, with dividends set to rise by 5% to 7%. Between 2018 and 2022, Xcel's capital budget is roughly $18.5 billion, with nearly a quarter of that earmarked for renewables (second only to the utility's spending on distribution). The yield is more in line with the broader utility industry at roughly 3.3%, with a modest payout ratio of target of between 60% and 70%. Income investors looking for a more traditional utility investment should take a look. The forward P/E of around 19 is middle of the road for the utility space.

3. Providing the world with power

AES isn't your typical U.S. utility company, with assets spread across 15 countries. In that way, it is a very different animal compared to NextEra and Xcel, and it's probably most appropriate for more aggressive investors. That said, the stock's 3.7% yield is more generous than the two companies above, and its forward P/E of around 11 is toward the low end of the utility industry.

Those are enticing figures, especially when you add that AES expects to grow earnings between 8% and 10% a year through 2022. The dividend, meanwhile, has been increased $0.04 a year recently, which amounted to 8% in 2018. (Note that the company only started paying a dividend in 2012, so its historical dividend growth rate is unrealistically high and not a reliable indicator of future growth potential.) If you are willing to handle the uncertainty involved with AES's far more diversified business model, it may be worth the extra legwork needed to understand the business.

NEE PE Ratio (Forward) Chart

NEE PE Ratio (Forward) data by YCharts.

Roughly 27% of its 34 gigawatts of capacity is renewable today. And while it plans to expand its renewable-power capacity over time, the most interesting thing about AES is its commitment to storage through a joint venture with Siemens called Fluence. This business is expected to expand rapidly, hitting 22 gigawatts of storage capacity by 2022 (roughly 10 times its current capacity). Storage is set to become a key piece of the renewable industry. Since wind and solar are intermittent sources of power, storage allows utilities to hold the power until it is needed and reduce their reliance on traditional generation to smooth supply. AES is a more complex story but is still worth the research effort even if you don't end up buying it.

Consider mixing things up

You could easily run out and buy renewable-only companies, but that focuses you on just one area of the power market. It's a growing niche, to be sure, but diversification and scale have benefits, including things like access to low financing costs. Don't get caught up in the hype surrounding renewable power; make sure to put old-school, diversified utilities like NextEra, Xcel Energy, and AES on your research list of renewable-power companies even though they don't look like renewable-power companies. You might just decide that owning one of these industry giants is a better fit for your portfolio than a company focused only on one niche in the energy space.

Reuben Gregg Brewer has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.