Operational Emissions in Prosuming Dwellings: A Study Comparing Different Sources of Grid CO2 Intensity Values in South Wales, UK†

Abstract

This paper analysed operational CO2 emissions from electricity grid interaction in photo-voltaic prosumer dwellings in South Wales, UK. Operational CO2 emissions were quantified in four prosumer dwellings aiming to analyse (1) the differences in the result when time-varying data and static emission factors are used, and (2) the association of load-matching indicators to the results. Electricity balance data were obtained through monitoring (April 2020 to March 2021), and three sources for the grid’s CO2 intensity were considered: (1) UK nationwide average time-varying values (UK), (2) South Wales (SW) average time-varying values and (3) the UK Government’s official CO2 emissions factor (EF) for the study period. UK and SW grid CO2 intensity were obtained as dynamic data flows in a 30 min resolution, whereas EF was a year constant. Gross CO2 emissions calculated using SW data reached the highest emissions results: between 67.5% and 69.3% higher than the results obtained using the UK time-varying data, and between 41.1% and 45.1% higher than using the EF. The differences between the obtained yearly net emissions using dynamic data and the EF in each studied dwelling ranged between 6.2% and 294%. Results also show that the definition of geographic boundaries for location-based approach calculations can significantly affect the obtained emissions values.