LONDON (AFP) ― Britain’s Tate Modern opens the former power station’s giant underground oil tanks as an art space on Wednesday, vastly increasing the capacity of the world’s most visited modern art gallery.

The tanks ― which measure 30 meters in diameter and seven meters high and once held one million gallons of oil ― are designed to accommodate giant installations, as well as host performances and projections.

The huge circular areas will help Tate Modern overcome a crippling lack of space for the five million visitors it welcomes every year, more than double the two million it was designed for when it opened in 2000.

Nicholas Serota, the director of the gallery’s parent institution Tate, said the development would also help it keep up with new trends in the art world.

“In the past 50 years, film, performance, installation and new media have become the chosen forms of expression for many of the most exciting visual artists,” Serota told a press conference at the gallery on Monday.

The huge iron tanks officially open on Wednesday with a dance work by Belgian choreographer Anne Teresa de Keersmaeker, which will be on show for free from July 18 to 20.

Suzanne Lacy’s Crystal Quilt, created after 430 women over the age of 60 gathered to share their views on getting older, is in the first tank.

A second tank contains South Korean artist Kim Sung-hwan’s new film “Temper Clay,” which juxtaposes his parents’ flat in Seoul, South Korea, with the family’s countryside home which they had aspired to retire to.

The tanks have been converted by Swiss architects Jacques Herzog et Pierre de Meuron.

Chris Dercon, director of Tate Modern, said they would be used to show “art in action.”

The tanks were decommissioned in 1981 when what was then the Bankside Power Station was taken out of service.

Serota wrote in the Daily Telegraph newspaper that when he first visited the underground chambers in 1993 “the smell of oil was still incredibly strong and there was a feeling of danger and hostility. But I saw real potential.”

Tate Modern opened in the brickwork building 12 years ago but its huge central Turbine Hall, which houses temporary exhibitions, eats up a huge amount of available space.

The museum has only around half of the exhibition space of galleries such as the Pompidou Centre in Paris or MoMA in New York, which only draw around half the number of visitors as Tate Modern.

The tanks will remain open to the public until October 28 as part of the climax of the Cultural Olympiad, the programme of events surrounding the London 2012 Games.