T. Boone Pickens grabbed headlines last year by adding wind energy to his ongoing investments in the oil patch. But across the country, investors who are not quite as famous are mimicking a new, pragmatic approach to energy investing call it the have-it-both-ways tack. On the one hand, they re continuing to invest in the traditional energy that will likely power our cars, heat and light homes, and run factories for decades to come. But they are also hedging those bets by plowing assets into greener and cleaner technologies. It s a strategy that echoes what some Big Oil companies are doing, from BP (BP), which has spent $3 billion over four years on wind, solar and biofuels, to Exxon Mobil (XOM), which is spending $600 million on research into biofuels. Even some utilities are taking the dual approach, operating old-fashioned coal and oil-fired plants while sinking money into wind turbines and solar-energy farms.

Behind the new approach is another kind of green: the promise of profits. Although the recession put a crimp in demand and prices, these investment pros are looking at the long-term economics of all types of energy. The U.S. Energy Information Administration projects that global energy consumption will jump 33 percent between 2010 and 2030, fueled mainly by demand in fast-growing nations like China and India. Since much of the world s easily found oil has already been tapped, oil companies will have to search increasingly risky and more expensive places to meet the rising demand.

Meanwhile, governments around the world have committed billions to develop renewable energies, such as wind and solar, and that commitment is likely to get another boost from a planned meeting of global leaders in December to hammer out a successor to the Kyoto Protocol global-warming agreement of 1997. In the U.S., Congress is debating a major climate-change bill that would impose stricter requirements to cut pollution, and give a big boost to green energy. Even China is putting its political muscle and billions of dollars into alternative energy, such as wind farms and power plants fueled by corn stalks.

All of this isn t exactly a secret, of course. But even after a rally in energy stocks from their March lows, savvy energy investors are looking for more gains over the next few years. Traditional-energy companies, already profitable at the recent oil price of nearly $75 a barrel, should benefit from higher demand fueled by an economic recovery. And while renewable-energy companies were hit hard in the recession, some are now trading at valuations that don t reflect their solid growth prospects, says Jesse Pichel, an analyst with Piper Jaffray. We scoured the energy landscape to find five firms that should grow along with long-term demand for their products.

Schlumberger

The economic plunge sent oil s price plummeting from nearly $150 a barrel last July to almost $30 a barrel in December. But now that crude prices have rebounded somewhat, the question is, once again, how much can companies drill, baby, drill, says Mike Breard, senior analyst with Hodges Funds, which has $320 million under management.

That means there s an opportunity for investors in Schlumberger (SLB) . The Houston-based oil-services firm helps customers mostly major Big Oil firms, like Exxon Mobil find and extract oil by setting up wells and maximizing their efficiency. About three-quarters of Schlumberger s $27 billion in annual sales comes from outside the U.S. As oil companies must move farther offshore to meet the world s demand, Schlumberger maintains a technological edge over the competition in today s increasingly complex drilling environments, says Michael Urban, oil-field services and equipment analyst with Deutsche Bank Securities. The company is active in deepwater operations in West Africa and also has a large presence in Russia.

Schlumberger till faces some near-term challenges. Drilling activity fell by as much as 60 percent over the past year in the U.S. and by as much as 30 percent in Russia. At the same time, demand for oil fell in the U.S. last year, and increasing demand from the emerging markets isn t enough to make up the difference in the short term, says Daniel Chung, chief investment officer for Fred Alger Management. But many analysts say that patient investors will find that Schlumberger s long-term potential far outweighs the company s near-term challenges.

Apache

As the recession unfolded and new reserves of natural gas hit the market, natural gas prices plunged about 75 percent. John Crum, Apache s co chief operating officer, tells SmartMoney that investors shouldn t expect prices to return to last year s peak of nearly $14 per million BTUs any time soon. We ve got a heck of a supply here, he says.

This might seem like bad news for a company that gets half its business from natural gas. But the other half oil has enjoyed a rebound from its lows, and Apache is using its disciplined investment strategy to respond to both developments. The Houston-based company won t drill unless oil is at least $40 a barrel and natural gas is at least $4.50 per million BTUs. So these days Apache (APA) is looking for oil but putting much of its search for natural gas on hold. But investors who have watched the company for years point to its long-term record of boosting production and reserves, through both acquisitions and efficient operations. They do a great job blocking and tackling, says Ben Halliburton, chief investment officer of money manager Tradition Capital, which bought shares this summer.

Maybe someone forgot to tell First Solar about the recession. Although worldwide demand for solar energy is expected to be flat this year, the maker of solar panels for power plants continues its streak: Earnings are expected to jump about 70 percent this year on a more than 55 percent increase in sales. Combine that with one of the lowest cost structures in the industry and analysts say the Tempe, Ariz. company s prospects are as bright as, well, the Arizona sunshine.

Even after all the excitement of recent years, solar energy still registers just a blip on the global energy screen. Worldwide, the solar panels sold last year can generate about as much electricity as one nuclear power plant, says Paul Clegg, equity analyst for Jefferies & Co. But that s changing fast. Some experts say that as the economy picks up and governments continue to favor clean energy, solar could grow by more than 40 percent a year. First Solar plans to be ready. It plowed $33.5 million into research and development in 2008, more than double the level of 2007. This year it plans to double its worldwide production, manufacturing enough solar panels annually to provide about 1,000 megawatts of electricity. Analysts say this should give First Solar (FSLR) an edge, as solar technology evolves from a niche product to a more widely used energy source.

Telvent

When New York State needed help unsnarling the state s crowded roadways, officials turned to Telvent (TLVT) . Traffic management is one of many services the company provides to improve efficiency in energy, transportation and other industries. And in the push for cleaner energy, efficiency is the low-hanging fruit, says Jack Robinson, manager of the $237 million Winslow Green Growth fund, which owns Telvent shares. Investing in energy savings costs less than developing new energy sources, and it has an immediate impact.

The stimulus package passed in February includes $4.5 billion for smart grid, a term that refers to automating energy transmission to create a more efficient and reliable network. Telvent, whose clients include utilities and governments around the world, hopes to get a piece of that. The company moved its headquarters from Madrid to outside Washington, D.C., last year, in part to help pick up more U.S. business, CEO Manuel Sanchez tells SmartMoney. North America will account for 30 percent of its sales in 2009, and Sanchez hopes to increase that to 40 percent over the next few years.

Massey Energy

America s least glamorous energy source has taken a pounding in the recession. Demand for coal from steel companies and utilities is down, competition from cheap natural gas is up, and cap-and-trade legislation in Washington threatens to boost coal s cost by putting a price tag on carbon emissions. The result? Coal stocks have been left for dead, says Jerry Jordan, manager of the Jordan Opportunity fund, which owns Massey Energy (MEE) shares.

For savvy investors, all those negatives could spell opportunity. Coal remains one of the cheapest and most abundant fuels powering half of the nation s electric output and America isn t likely to wean itself from coal for decades. Richmond, Va. based Massey is poised to benefit: It s the nation s fourth-largest coal producer and the largest coal company in Central Appalachia, with 36 percent of the region s reserves.