Decarbonizing a national energy system through electrification by sector coupling power, district heat, transport and buildings

The energy sector is responsible for the majority of emitted carbon dioxide (CO2) emissions globally. This study examined the achievable CO2 emission reductions with electrification through sector coupling, in a national energy system. The analysis included electrification of district heat generation, passenger vehicle transport and building stock, while simultaneously the share of wind, solar photovoltaics and nuclear power were increased in power generation. With the increased emission free power generation and sector coupling of the electrified energy sectors, significant emission reductions were achieved, as the set 95 % emission reduction target of 1.77 megatons (Mt) CO2 was reached with several scenarios. This target was reached with and without increased nuclear power capacity, however, without increased nuclear power with 610 million euros higher annual costs. The least costly scenario to achieve this target had annual costs of 25.4 billion euros (14.2 for vehicles, 7.1 for electricity generation, 0.9 for district heat generation and 3.2 for the building stock). A 90 % emission reduction target was achieved with only 150 million euros lower annual costs. Without retrofits conducted in the building stock, or without electric vehicles, the 95 % reduction target was not achieved. In addition, required dispatchable reserve power capacity was significant, 14–41 % of peak load, whereas excess power generation varied between 6 % and 28 %. For district heating, thermal storage was found to be the least costly measure to obtain further emission reductions. Annual variations were great for both emissions (2.9 Mt. CO2) and the reserve power requirement (3 gigawatt).