The indirect CO2 emission implications of energy system pathways: Linking IO and TIMES models for the UK

Radical changes to the current national energy systems – including energy efficiency and the decarbonisation of electricity – will be required in order to meet challenging carbon emission reduction commitments. Technology explicit energy system optimisation models (ESOMs) are widely used to define and assess such low-carbon pathways, but these models only account for the emissions associated with energy combustion and either do not account for or do not correctly allocate emissions arising from infrastructure, manufacturing, construction and transport associated with energy technologies and fuels. This paper addresses this shortcoming, through a hybrid approach that estimates the upstream CO2 emissions across current and future energy technologies for the UK using a multi-regional environmentally extended input output model, and explicitly models the direct and indirect CO2 emissions of energy supply and infrastructure technologies within a national ESOM (the UK TIMES model). Results indicate the large significance of non-domestic indirect emissions, particularly coming from fossil fuel imports, and finds that the marginal abatement cost of mitigating all emissions associated with UK energy supply is roughly double that of mitigating only direct emissions.