If there is a big/risky decision, but it is unclear how it can be ‘rationally’ made (criteria keep changing, indicators are murky) then it is logical to try to keep your options open, even if that means incurring some costs – what if you choose wrong, and look like a muppet?!
So, you don’t build another big power plant, you just keep doing running repairs on the ageing one that you’ve got (perhaps even keeping it open after you intended to close it, because you are waiting for the politicians to make a firm decision on the price of carbon, or the incentives for renewables etc)
According to Cambridge Dictionaries Online, to “hedge your bets means “to protect yourself against loss by supporting more than one possible result or both sides in a competition”