The Eden Project is planning to expand by building a desert landscape under a 150ft dome and a 200-bedroom low-energy hotel with walls made of rubble, if the necessary terrain and funding can be acquired.

The centrepiece of the new plan is a third biome containing sandbanks and desert plants such as cacti. Three intersecting domes, 150-high and 380ft wide would keep rain off the dunes.

Alongside the hotel, an education centre and conference facilities are planned as well as a park and ride shuttle system using sustainable fuels and a music venue to rival the Glastonbury festival.

The five-year expansion plan is expected to cost £105m, £16m more than the original Eden and would mean the attraction could take an extra 1m visitors a year.

'We're not resting on our laurels,' said an Eden spokesperson. 'But the plans rest on raising the necessary funds and land acquisition.'

In addition to employment, Eden is thought to have generated £155m of extra spending in the southwest and Cornwall.