Imperial College London


Faculty of EngineeringDepartment of Chemical Engineering

Reader in Energy Systems



+44 (0)20 7594 9300a.hawkes




Ms Quasirat Hasnat +44 (0)20 7594 7250




C502Roderic Hill BuildingSouth Kensington Campus






BibTex format

author = {Hawkes, AD},
journal = {Energy Policy},
pages = {5977--5987},
title = {Estimating Marginal CO2 Emissions Rates for National Electricity Systems},
volume = {38},
year = {2010}

RIS format (EndNote, RefMan)

AB - The carbon dioxide (CO2) emissions reduction afforded by a demand-side intervention in the electricity system is typically assessed by means of an assumed grid emissions rate, which measures the CO2 intensity of electricity not used as a result of the intervention. This emissions rate is called the “marginal emissions factor” (MEF). Accurate estimation of MEFs is crucial for performance assessment because their application leads to decisions regarding the relative merits of CO2 reduction strategies. This article contributes to formulating the principles by which MEFs are estimated, highlighting the strengths and weaknesses in existing approaches, and presenting an alternative based on the observed behaviour of power stations. The case of Great Britain is considered, demonstrating an MEF of 0.69kgCO2/kWh for 2002 to 2009, with error bars at +/-10%. This value could reduce to 0.6kgCO2/kWh over the next decade under planned changes to the underlying generation mix, and could further reduce to approximately 0.51kgCO2/kWh before 2025 if all power stations commissioned pre-1970 are replaced by their modern counterparts. Given that these rates are higher than commonly-applied system-average or assumed “long term marginal” emissions rates, it is concluded that maintenance of an improved understanding of MEFs is valuable to better inform policy decisions.
AU - Hawkes,AD
EP - 5987
PY - 2010///
SP - 5977
TI - Estimating Marginal CO2 Emissions Rates for National Electricity Systems
T2 - Energy Policy
VL - 38
ER -