How much co2 does a standard industrial oil fired boiler emmitt compared to a wood pellet boiler?
It is not just how much CO2 is emitted but where the Carbon came from. In wood pellets or other biomass, the Carbon has been fixed from atmosphere during the growth of the plant in very recent time. In fossil oil the Carbon was fixed from plant life millenia ago and thus burning fossil fuel releases C that has been locked up for ages.