On the dusty southeastern corner of the University of Texas at Arlington is an odd sight for a university campus: more than 20 natural gas wells.

But spectacles such as this - which is part of an initiative yielding a per cent royalty that has generated $10 million (?6.2 million) for the institution in the past three years - are becoming more common at the US universities sitting on energy deposits. Such institutions have found a new way to make money: by drilling for oil and natural gas.

The Arlington campus "happened to be on a sweet spot" in the Barnett Shale natural gas field, said university spokeswoman Kristin Sullivan.

"I'd say the issue came down to being good stewards of the available natural resources and making sure the revenue was used to benefit our students, faculty and university overall," she said.

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In fact, public universities in Texas have always benefited from oil and gas drilling, thanks the state legislature's creation in 1876 of the Permanent University Fund, which draws on the revenues from grants of land rich in oil, gas, sulphur and water.

But drilling on campus is new, and Texas is not the only place it is happening. Universities in Indiana, West Virginia, Ohio and Pennsylvania have also signed leases with energy companies or have been given the authority to do so.

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Indiana State University has signed a deal with an energy firm to drill for oil and gas on campus, with the university receiving 15 per cent of the revenue. A law passed in Pennsylvania in October allows that state's 14 public universities, whose budgets were cut by 18 per cent in 2011, to lease parts of their campuses for natural gas drilling.

And under a law that took effect on 30 September, Ohio's 13 public universities and 24 branch and regional campuses are inventorying oil and natural gas lying beneath their campuses for a new commission that will lease mineral rights on state land to the highest bidders.

In addition to the need for new revenue to make up for state budget cuts, the university drilling craze is being spurred by an increasingly common but controversial process called hydraulic fracturing, or "fracking", under which a mixture of water and sand is pumped at high pressure into wells to push natural gas to the surface.

Concerns about the safety of this process, already raised in many parts of the world including the UK, are growing at US universities.

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"It's an exceptionally dangerous industry that shouldn't be anywhere near a college campus," said Robert Myers, director of environmental studies at Lock Haven University in Pennsylvania.

"Certainly funding for higher education is extremely tight, and has been for a long time. But this is not the way to fund our universities."

Critics contend that fracking has spilled hundreds of thousands of gallons of chemicals into drinking-water supplies, and may even set off small earthquakes. It was blamed for causing tremors during testing in England's North West last year.

"Is this really the kind of thing we should have in the middle of the campus quad? Maybe next we can log the trees on campus," Dr Myers added sarcastically.

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"It really is sort of an appalling way to pay for higher education."