Pipeline companies are often likened to toll booths because they collect a fee when oil and gas pass through their systems. Those payments really add up, especially for those that operate the largest networks in North America. Furthermore, with minimal maintenance capital required to keep those volumes flowing, energy infrastructure companies tend to be cash cows, which is why most pay above-average dividends.

Among the biggest cash cows are Kinder Morgan (NYSE:KMI), Enbridge (NYSE:ENB) and TransCanada (NYSE:TRP), which each generated billions of dollars in free cash flow last year. Plus, with pipelines filled with growth projects, all three should produce even more cash flow in future years.

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Generating lots of cash in a down year

Last year Kinder Morgan produced a whopping $4.5 billion of distributable cash flow. While that was down from $4.7 billion in 2015 as a result of some asset sales and the impact of the oil market downturn, the company still generated more cash than any of its rivals. While the company anticipates that its cash flow will dip again this year to $4.46 billion, its cash-generating engine should reaccelerate in 2018 when several major projects enter service, including its Elba Island liquefied natural gas (LNG) export facility.

Before the oil market downturn, Kinder Morgan returned just about all of its cash flow to investors via dividends. However, it slashed that payout in 2015 to help reduce debt and finance growth projects. Because of that, the company only currently returns about a quarter of its cash flow back to investors each year. However, as a result of several strategic initiatives to shore up its balance sheet, Kinder Morgan is positioning itself to deliver a big dividend boost starting next year, with expectations that it could pay out about half of its cash flow each year. That would still leave the company with ample capital to finance growth projects and increase its income stream.

Hitting the accelerator

Canadian pipeline giant Enbridge generated an impressive 3.7 billion Canadian dollars ($2.76 billion) of available cash flow from operations last year, which was up a remarkable 17.7% from 2015. The company returned more than CA$1.9 billion of that cash to investors last year via dividends, or about 52% of available cash flow. That said, Enbridge's cash flow will surge even higher this year because it recently added U.S. pipeline company Spectra Energy into the fold, which generated nearly $1.4 billion in distributable cash flow last year. Because of that deal, the company anticipates increasing its dividend by 15% this year alone.

However, there's much more growth coming down the pipeline at Enbridge thanks to its monster CA$26 billion near-term project backlog. The company anticipates that those projects alone should support 12% to 14% annual growth in available cash flow from operations through 2019. Meanwhile, the company has another CA$48 billion of longer-term projects, which it anticipates will grow its cash flow to such a degree that it can support 10% to 12% annual dividend growth through 2024 while maintaining a conservative payout ratio of 50% to 60% of cash flow.

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Best year ever and there's more where that came from

For Canadian energy infrastructure giant TransCanada, 2016 was also a transformational year. Thanks to the acquisition of Columbia Pipeline Group, the company exceeded CA$5 billion ($3.81 billion) in operating cash flow for the first time in its history. Meanwhile, after factoring out maintenance spending and dividends on preferred shares and other distributions, the company generated CA$3.66 billion ($2.74 billion) in distributable cash flow, up 2.9% from 2015. The pipeline giant returned about 47% of that cash flow to investors via dividends last year.

Like its rivals, the cash-generating capacity at TransCanada is only expected to grow over the next few years thanks to its ambitious growth program. Overall, the company has CA$23 billion of near-term expansion projects under way, which should supply it with a growing stream of cash flow. In fact, the company expects that it will be able to grow its dividend by 8% to 10% per year through 2020 while maintaining a conservative payout ratio.

Investor takeaway

Kinder Morgan, Enbridge, and TransCanada operate some of the largest energy toll roads in North America. Because of that, these companies generate billions of dollars in cash flow each year. That's more than enough money so that all three can pay out a large percentage of it in dividends while still retaining ample cash to reinvest into growth projects that will increase future cash flows.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.