Any delay in climate change polices meant to limit an increase in global warming to 2 degrees centigrade will not benefit companies operating or thinking of building coal-fired powered plants, a study has found.

In fact, any such delay could cause more problems for owners of such power plants than meeting the goal, says researcher Nils Johnson of the International Institute for Applied Systems Analysis.

The problems, he says, is that any new coal-fired plants would be expected to operate for 30 to 50 years and would begin to show a profit only after operating for many years.

Climate polices will eventually make the costs of emissions rise to the point where coal-derived power loses its ability to be competitive, so any newly-built plants would be forced to shut down and go idle long before owners or investors could ever see a return on their investments.

The problem is called stranded capacity.

"If we are serious about meeting climate targets, then the reality is that eventually we will have to start shutting down coal-fired power plants," Nils Johnson said. "But the longer we delay climate action, the more stranded capacity we'll have."

As much as a third of global investment in the coming decades in coal-fired power plants -- mostly in India and China -- could end up as stranded capacity if action on global warming targets is delayed, Johnson said.

"Delaying action encourages utilities to build more coal-fired power plants in the near-term. Then, when policies are finally introduced, we have to phase out coal even more quickly and more investments go to waste."

Options to avoid construction of new coal power plants could include moving to other types of power plants such as nuclear or hydrolelectric, keeping older coal plants operating and improving efficient use of energy.

More efficient use of energy could lower the amount needed to be generated and lessen the pressure to build new power plants.

"The best strategy would be to stop building new coal power plants starting today," Johnson added.

If governments prove unwilling to limit construction of new coal power plants, Johnson and his IIASA colleagues say, they might consider grandfathering existing facilities to make them exempt from future climate policies, or equip plants with Carbon Capture and Storage, a technology, as yet unproven, that could capture the emission of greenhouse gases for underground storage.

If CCS technology were adapted it would require hundreds of coal-fired power plants to be retrofit with such systems quickly, the researchers said.

"CCS could buy us time, but what if it doesn't work? It's a risky strategy," Volker Krey, co-author of the IIASA study, says.