In a world awash with cheap oil and plunging profits, one obscure corner of the energy business is shining brightly: the owners of storage tanks.

While not nearly as famous as giant oil producers like Exxon Mobil Corp. and Royal Dutch Shell Plc, storage companies including Vopak NV, Kinder Morgan Inc., Oiltanking GmbH and Magellan Midstream Partners LP are among those benefiting from rising demand for onshore tanks -- and higher prices to rent limited space.

“Storage is king,” said Jean Francois Lambert, global head of commodity finance at HSBC Holdings Ltd. in London. “Good tanking at the right location could make money.”

Driven by record production from shale fields, the oil glut is bigger in the U.S. than any other region, and particularly large around the hub of Cushing, the Oklahoma town that calls itself the “pipeline crossroad of the world.” The International Energy Agency anticipates that total U.S. stocks levels, already at a 80-year high of 459 million barrels, may soon test the limits of the country’s tank capacity.

In the U.S. and beyond, traders are filling tanks to take advantage of contango -- a relatively rare situation where forward prices are higher than current prices, allowing people to buy oil cheap, store the commodity in tanks and sell later, all the while locking in their income through the use of derivatives.

The price difference between a West Texas Intermediate oil contract for immediate delivery, the benchmark for U.S. prices, and the one-year forward -- a measure of the contango -- stood at minus $12.59 a barrel on Thursday, close to the highest since crude prices started falling last year.

Oil traders believe that tank farms at Cushing will fill up as soon as late April, triggering a race to secure the last remaining tanks in the city.

“Demand for our storage services in Cushing has been robust,” said Robb Barnes, senior vice president for commercial crude oil at Magellan, a company with 12 million barrels of tanking capacity in the Oklahoman town. The company said all its tanks were already leased.

Mark Hurley, chief executive officer of Blueknight Energy Partners, a company with 6.6 million barrels of tank capacity at Cushing, told investors increased demand for his tanks meant fees had “been changing fairly rapidly over the last six months. Obviously, on the rise.”

Storage companies keep the exact level of their fees confidential but oil traders said they charge around 20 U.S. cents to 50 U.S. cents a barrel a month, depending on the length of the contract.

The dearth of storage capacity is such that traders said short-term lease rates for the most sought after locations, such as Cushing, have gone up to as much as 80 U.S. cents a barrel.

In 2008 and 2009, the last time the oil market was as oversupplied as today, the storage companies were slow to increase rates, allowing the traders who used their tanks to take an unusually large slice of the contango profit. This time, the split between tank owners and traders is more even, according to Mike Conway, head of trading at Shell in London.

“It looks like the owners of the storage facilities have extracted a bit more value for themselves,” he said in an interview.

Investors are taking notice. In dollar terms, the share price of Vopak, the world’s largest independent oil storage company, has risen 4.4 percent since the beginning of the year. Vopak owns onshore tanks capable of storing roughly 210 million barrels of crude oil and petroleum refined products -- enough to supply Germany for almost three months.

In the same period, the MSCI World Energy index has dropped more than 7 percent weighed by lower oil prices.

Across the board, oil storage companies have told investors to expect stronger income in 2015 than in 2014.

On top of a dozen of publicly listed oil storage groups, the increase in demand would be a boon for privately owned companies such as Oiltanking, a unit of German-based Marquard & Bahls AG, and VTTI BV -- a venture including Vitol Group, the largest independent oil trader.

“You’ll find all the locations around the world that can store crude now, like Saldanha Bay or the Caribbean, are going to be full,” Jared Pearl, VTTI’s commercial director, said in an interview this week. “It would be crazy if they weren’t.”

The higher demand and fees are not the only factor boosting incomes. Some storage companies also take advantage of the contango by buying themselves crude oil for storage.

“We have five percent of our tankage in Cushing that is really for own account,” Greg Armstrong, CEO of Plains American Pipeline LP, told investors last month. The company “There are areas where we have strategically pilled off opportunities or massive tankage for our own account.”