The Royal Institute of British Architects (RIBA) has launched a competition seeking “inspiring and innovative” ideas for the reuse of surplus gasholder bases – huge containers storing natural gas – across the UK.

Once prominent across Britain, in recent years the numbers of gasholders in active use have dwindled. Now the National Grid Company, which manages the land they are built on, plans to dismantle them and find a new leisure uses for the sub-surface voids left behind by their large cast-iron frames and bases.

“These voids represent an opportunity for repurposing and the competition is seeking alternative uses rather than the default practice of backfilling the holder,” said RIBA’s competitions arm in a statement.

The initial phase of the competition will require digital submissions only, with five concept designs shortlisted for further development at the second phase. The deadline for first stage submissions is Tuesday 10 October 2017.

Each shortlisted designer will receive an honorarium of £3,000 (US$3,900, €3,200), and the winner will receive an additional £4,000 (US$5,200, €4,300). There may be an additional payment of £1,000 (US$1,300, €1,090) for a highly commended scheme.

Previous examples of gasholder reuse include Bell Phillips Architects’ Gasholder Park near London’s King’s Cross Station. The Grade II listed frame of the Victorian-era Gasholder No. 8 was painstakingly dismantled, refurbished and rebuilt in a new location next to Regent’s Canal, framing a polished stainless steel canopy surrounding a wide area of green space.

Architects WilkinsonEyre used other gasholders nearby to hug 145 canalside apartments and penthouses.