Unmined coal in Wales could be the answer to Britain's energy crisis, an MP told the Commons on Wednesday.
Tower Colliery is the only deep mine left in south Wales
Ogmore MP Huw Irranca-Davies also argued that "clean coal" technology could make the fuel eco-friendly.
A 1979 survey found 250m tonnes of good quality coal in Wales, but only 20m has been mined because of the pit closure programme during the 1980s.
The reserves could provide fuel for power generation for 50 years or more, Mr Irranca-Davies told fellow MPs.
He told the BBC Wales's Good Morning Wales programme that he was not backing a "wholesale reopening" of the Welsh pits but said a solution to Britain's energy crisis was urgently needed.
By 2020 the 32% of electricity generation in the UK provided by coal will disappear.
"Clean coal technology with zero emissions from these new generating plants is one of the ways forward and I'm optimistic the government will look at this quite favourably," the Labour MP said.
He added that the technology had been in place for a number of years now - particularly in the United States where emissions are treated to reduce their polluting effect.
The gas can also be extracted from coal to make it cleaner when burning.
And he said a process called "carbon sequestration" - pumping deposits into gas and oil reserves under the North Sea - could also be used.
"It seems like absolutely amazing science fiction... but it's already being done in Algeria and elsewhere, and highly productively."
The MP believes the UK could also export clean coal technology to countries like China, which is opening about one coal plant each week to satisfy energy demands.
But a Greenpeace spokesman said using carbon sequestration on a large scale could be 10 to 15 years away.
Climate campaigner Mark Strutt said: "There are some pilot projects but a lot of the technologies we need to fit together are still years away. We have to do something about climate change now.
"The money that will have to be spent on clean coal technology will be better spent on renewable sources of energy like wind power - which we know works."
Only one deep pit remains in south Wales, Tower Colliery near Hirwaun.
The mine was bought by managers and workers at the plant in 1994 after British Coal said it was "uneconomic" to run.
UK Coal's Stuart Oliver told the BBC News website that re-opening old mines in Wales would be expensive.
He said: "In the last 10 years 20 mines have closed - all these mines will be very, very costly to recover. But they technically could be recovered if you had that money to invest in a mining project."
Mr Oliver said it would take eight to 10 years to build and commission a new mine.
- Tower Colliery has been pledged another £843,000 by the UK government. The cash brought Coal Investment Aid to the colliery to £3m over the next five years.