Clean Coal theory is dangerous. As global warming skeptics constantly point out, there's always some uncertainty about theories.
Why is Clean Coal just a theory? Because no one has yet shown that the amount of CO2 that needs to be captured to establish a viable, clean coal-fired electricity system can be safely and permanently sequestered. It requires a lot of emptiness - underground reservoirs where the carbon can be stored under very high pressure. The reservoirs need to be in reasonable proximity to the capture source. The further you need to pump the stuff the greater the expense and the risk of something going wrong.
Here's a little something they don't want to tell you: there's not remotely enough reservoir space to pull this off. That's why it's all gimmickry, a diversion. So if, in theory, you had an infinite amount of reservoir space and if, in theory, enough of that reservoir space was suitable to safely store high pressure CO2 and if, in theory, enough of that suitable reservoir space was sufficiently close to make sequestration economically viable, then you've got, in theory, an answer.
So, the first question for Mr. Harpo - how much viable storage capacity exists? Second question - how much CO2 can be safely and permanently sequestered in the existing storage? Third question - how much of Canada's electricity requirements can ever be realized through clean coal technology?
It sounds great, in theory, but sometimes you have to ask the practical questions.