A buddy and I talked stocks and retirement the other day. He wants income from his investments, but also wants "investment grade" safety. With the growth of U.S. energy production, U.S. midstream energy companies offer compelling dividends and safety. Below are three to consider, each with its own nuances for income investors.

Safe, growing dividend
For income investors looking mainly for safety with a slowly growing dividend, Enterprise Products Partners (NYSE:EPD) offers the safety of a $72 billion enterprise value, a current yield of 4.5%, and a distribution coverage ratio of about 1.5. The company also boasts a distribution growth rate of roughly 32% over the past five years. Add in the stock's appreciation from about $20 in 2008 to about $63 today and Enterprise looks like a winner in every respect.

This is great news for those who have been holding the stock since 2008, but what about the company's future? Enterprise plans to expand its Houston Ship Channel liquefied petroleum gas facility and build a new facility at a site yet to be determined. These facilities will allow Enterprise to export propane or butane to the world. Crude oil operations will also grow, as the company reports a major build-out in its ECHO storage terminal on the Gulf coast and expansion of its Eagle Ford and Seaway pipelines.

Underpinning this growth is a growing distributable cash flow and a slowly decreasing cost of debt. The company's cost of debt has decreased from 6.1% in 2009 to 5.4% today. The company currently reports a debt-to-adjusted-EBITDA of 3.6, reflecting a steady improvement since 2009. Most of its debt comes due in 10 to 30 years. All these factors point to continued growing, safe income.

Nice yield with recent capital gains
In 2009, Energy Transfer Partners (NYSE:ETP) paid $3.57 per unit in distributions. The following year, the distribution grew to $3.58 per unit and stayed there through the first half of 2013. The company's current yield is 6.8%. Why didn't Energy increase its distributions like so many others? It's primarily because Energy Transfer shipped natural gas using an energy-sales model rather than a fee-based model. This exposed the company to fluctuations in natural gas prices.

In 2012, Energy Transfer took two measures to improve its business. It began shifting to a fee-based leasing business model for its pipeline services. This helped the company achieve positive earnings surprises for the past three quarters. It also purchased Sunoco and made a further investment in Sunoco Logistics Partners. This will expand Energy Transfer's more lucrative oil and natural gas liquids operations.

So is Energy Transfer investment grade? Its distribution coverage ratio squeaked up to 1.05 from 0.95 for the previous quarter. That's marginally good news. Fitch Ratings calculates Energy Transfer's debt-to-EBITDA to be 4.2 or so at the end of the 2013 fiscal year. This is an improvement from last year's ratio of 4.6. Improved revenues from oil and natural gas liquids and a drop in capital expenditures should further improve the company's finances. All told, Energy isn't as strong as Enterprise, but its fiscal health is improving.

Small player, big growth
At less than 5% of the enterprise value of Enterprise Products, Genesis Energy (NYSE:GEL) offers a distribution of about 4%, but has superior distribution growth compared to Enterprise. Genesis increased its distribution 62% over the past five years, compared to 32% for Enterprise. Genesis' stock also gained almost 50% this past year as compared to about 15% for Enterprise.

Driving this growth are three business segments. First, its pipeline business transports crude oil from the South, Midwest, and Gulf of Mexico to Gulf Coast refineries. Genesis also pipes CO2 gas to the field to help producers squeeze more production from their assets. The second segment is sulfur removal services that the company provides to refiners. Genesis employs a proprietary process of removing sulfur and creating sodium hydrosulfide (NaHS) in the process. It collects this sodium hydrosulfide as payment in kind from refineries, and sells it to mining, pulp/paper, and other companies. In the third segment, Genesis provides logistical services for refined products downstream of refineries.

The company's fiscal health presents a mixed picture. Most notably, Genesis reports its debt-to-EBITDA on a pro forma basis at a healthy 2.87. This is an improvement over the 3.46 from 2012. The distribution coverage ratio is around 1.2, just a bit above the minimum of 1.0 that you would expect from a financially healthy company. The company grew its logistics operations over the past year with more in store. These should further improve the company's financial health.

Foolish final thoughts
For those seeking income, these three midstream companies offer three different ways to obtain it. Enterprise offers safe, steadily growing distributions backstopped by its sheer size and steadily improving debt picture. Energy Transfer offers a higher initial yield, but has less solid financials. Genesis offers strong growth in both distributions and stock price with sound financial footing. None of these is a bad investment, though you have to decide what's important to you and invest accordingly.

Robert Zimmerman is Long Jan 2014 $60 puts on EPD. The Motley Fool recommends Enterprise Products Partners L.P.. 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.