It's the impurities in the coal that cause the polution, not the coal itself. Coal can be cleaned up, but the more effort that is invested in cleaning it, the higher its cost and the less attractive it is as an energy source.
ANY carbon-based fuel produces carbon dioxide, even his own body.
This guy writes like a naive little 12 year-old. He uses all the PC cliches but has little or no knowlege of thermal processes.
Simplistic explanation of CO2 production variations between coal and other hydrocarbons -
All hydrocarbon combustion processes react both carbon and hydrogen with O2 to generate energy.
The Carbon reaction creates CO2, the Hydrogen H2O (ideally).
But these fuels vary in their proportions of C and H
Coal - lots of C, little H, so plenty of CO2 per unit energy.
Natural Gas - little C, lots of H, so less CO2 per unit energy.
Liquid hydrocarbon fuels are in between.