The global economy is slowly moving away from fossil fuels and toward renewables. The transition, however, will take quite some time, which is why investors shouldn't completely give up on oil stocks. 

Three that our contributors currently think are excellent buys this month are Clean Energy Fuels (NASDAQ:CLNE), ConocoPhillips (NYSE:COP), and Total (NYSE:TOT). Here's why this trio stands out.

An oil pump and storage tanks with the sun rising in the background.

Image source: Getty Images.

Roots in the oil business, but the future looks renewable

Jason Hall (Clean Energy Fuels): Much ink has been spilled touting battery-electric and hydrogen fuel cells as the alternatives that will propel the future of transportation. And while both -- particularly battery-electric -- will continue to make headway, investors are making a mistake to sleep on Clean Energy Fuels. Today, natural gas is the company's biggest business, making up about 70% of its fuel volumes, but growing demand for renewable natural gas, or RNG, is quickly turning it into an alternative fuels growth story. 

RNG, which is produced from human and animal waste products, is immensely beneficial when used as a vehicle fuel. Not only is it far-less polluting than diesel or gasoline, with almost no particulates and much lower carbon emissions, but because it captures the methane from landfills, farms, and wastewater treatment facilities and repurposes it, it mitigates the environmental impact of allowing that methane to enter the atmosphere. 

Clean Energy Fuels is the undisputed leader in natural gas for transportation in North America with over 500 refueling stations. Moreover, sales of RNG, which it brands as Redeem, increased almost 90% in the first quarter, and now make up over 30% of total sales. 

But I expect this company is just getting started. A recent deal with UPS -- the biggest long-term refueling contract ever for RNG -- makes it abundantly clear that it's a real-deal alternative fuel for serious transportation users. For investors looking to profit from the transition away from diesel and gasoline, Clean Energy Fuels represents an excellent opportunity for years of growth, as more commercial transporters make the move to a renewable fuel that's proven, affordable, and available now. 

What he said

Tyler Crowe (Total): Investors don't have to pick between oil and gas stocks or renewable energy stocks. To choose one to the exclusion of the other means either ignoring the clear trend that we're transitioning away from fossil fuels, or underestimating the monumental hurdles that we have yet to clear in that shift. So why pick a side when you could chose a company that lets you profit from both?

That is what French oil giant Total is today. Sure, it's one of the biggest oil and gas companies out there, but it's also making considerable investments in the bleeding-edge technology companies in the solar and wind power, battery, and smart grid spaces. Thanks to the cash-generating abilities of its oil and gas unit, it has the flexibility to take make lots of bets outside of fossil fuels in hopes of finding a model that will eventually replace its current baguette-and-butter business.

What's even more encouraging about this strategy is that Total is adept at generating a lot of value from its current business. Its return on average capital employed is the best among its Big Oil peers, and its production portfolio is profitable with crude at less than $30 a barrel. With a high-margin business in place, it can afford to take those shots without having to worry about keeping its current business funded.

Total's alternative energy investments are far ahead of most of its oil and gas peers, and it intends to build that portfolio further. For investors looking to invest in oil now and also get exposure to the alternatives that will power the future, Total is one stock to look at seriously today. 

An oil pump at twilight.

Image source: Getty Images.

A cash flow machine for a great price

Matt DiLallo (ConocoPhillips): U.S. oil giant ConocoPhillips shifted its operating strategy a few years ago. It not only narrowed its focus to its best assets but also changed its approach to capital spending. That has enabled it to generate more free cash flow, which it's increasingly returning to shareholders.

The company has already boosted its dividend three times in the past three years, while also ramping up its stock repurchase program. ConocoPhillips currently expects to buy back $3 billion of its shares this year, which it can easily fund with a combination of cash flow and cash on hand. In fact, with oil prices well above the company's $50 budget level, it's on track to produce an even larger gusher of cash flow in 2019. That could enable it to boost its buyback program as well as increase its dividend again later this year.

Despite the company's strong operating and financial performance so far this year, its stock performance has been underwhelming. While oil prices have climbed more than 14% in 2019, shares of ConocoPhillips have fallen by about 3%. Because of that, the stock trades at an attractive valuation these days.

With shares trading at a bottom-of-the-barrel valuation, ConocoPhillips' buyback program will be even more effective at creating value for shareholders. That increases the upside, making it one of the top oil stocks to buy this month, in my opinion.