Suppose an electricity consumer consumed 21000 kWh electricity supplied by the national grid in a specific year when the emission factor of the UK electricity generation was found to be 494.60 g CO2-eq/kWh. Provide a brief but reasoned discussion on whether the consumer's carbon footprint resulting from the electricity consumption can be accurately calculated in the following way: Carbon footprint of the grid electricity consumer = 21000 kWh * 494.60 g CO2-eq/kWh = 10386600 g CO2-eq = 10.3866 tonne CO2-e