MADRID, Nov 10 (Reuters) - Spain's Supreme Court on Friday gave power utility Naturgy the green light to temporarily close five gas plants, more than half a decade after it first asked the country's authorities to do so.

Asked whether the group would still go ahead with mothballing the plants, a Naturgy spokesperson declined to comment.

In 2017, when the company first approached Spain's Energy Ministry about temporarily closing them, the plants' limited use in the face of a growing share of renewables in the country's energy supply had made them unprofitable.

However the units, known as combined cycle power plants, were the main source of energy in Spain last year, providing almost a quarter of the electricity consumed in the country and acting as an important backstop to intermittent renewables.

Companies and industry bodies have called for government support for gas-fired plants, including so-called capacity mechanisms, which provide payments for them to be available to produce electricity when necessary.

The Spanish government is looking into the proposals. Heatwaves driving up use of air conditioning this summer as temperatures rose above 40 degrees Celsius (104 Fahrenheit) showed the importance of backstop energy sources.

At times, all available gas plants had to be turned on to cope with the demand. (Reporting by Pietro Lombardi; Editing by David Latona and Jan Harvey)