The Eden Project has secured £17m funding for a geothermal project, drilling 4.5km underground.
This funding will enable the Cornwall visitor attraction to build a power plant which will take energy from the heat in underground granite rocks.
On a site the size of a football pitch, the plant could produce power for the Eden Project and the local area.
The money is from a European fund, Cornwall Council and Institutional investors.
The Eden project is in partnership with EGS Energy, also based in Cornwall.
After a 10-year campaign to bring the green technology to Cornwall, the £16.8m funding will enable the partners to start drilling next summer.
Eden co-founder Sir Tim Smit said securing the funds and enabling an energy revolution was the biggest leap for Eden since it opened in 2001.
"Since we began, Eden has had a dream that the world should be powered by renewable energy."
The answer "lies beneath our feet" in the heat underground, he added.
Heating for biomes
"Now we have the green light and the funding to start drilling we are determined to make this technology work."
About £9.9m funding has come from the European Regional Development Fund (ERDF); £1.4m from Cornwall Council; and Institutional investors have contributed the remaining £5.5m.
The funding will pay for the first phase of the project, involving drilling one well which will initially supply a district heating system for the biomes, offices and greenhouses at Eden.
It will pave the way for the second phase which includes another 4.5km well and an electricity plant.
Completion of the second phase would mean Eden would be generating sufficient renewable energy to become carbon positive by 2023.
"Once up and running, our plant will provide more than enough renewable electricity and heat for the whole site, as well as for the local area" Sir Tim said.