The UK's energy mix consists of a variety of sources, including natural gas, coal, nuclear and renewable energy. In terms of carbon emissions, coal and natural gas produce the most CO2 per unit of energy generated, while nuclear and renewables produce much less. To produce less CO2 when carbon intensity is low, you should aim to use electricity during times when renewable sources are producing a larger share of the energy mix, such as on sunny and windy days when solar and wind power are abundant.