In the booming research on the environmental footprint of, for example, electrical vehicles, heat pumps and other (smart) electricity consuming appliances, there is a clear need to know the hourly CO2 content of one kWh of electricity. Since the CO2 footprint of electricity can vary every hour; the footprint of for example an electric vehicle is influenced by the time when the vehicle is charged. With the availability of the hourly CO2 content of one kWh, a decision support tool is provided to fully exploit the advantages of a future smart grid. In this paper, the GWP (Global Warming Potential) per kWh for each hour of the year is calculated for Belgium using a Life Cycle Assessment (LCA) approach. This enables evaluating the influence of the electricity demand on the greenhouse gas emissions. Because of the LCA approach, the CO2 equivalent content does not only reflect activities related to the production of the electricity within a power plant, but includes carbon emissions related to the building of the infrastructure and the fuel supply chain. The considered feedstocks are nuclear combustible, oil, coal, natural gas, biowaste, blast furnace gas, and wood. Furthermore, renewable electricity production technologies like photovoltaic cells, hydro installations and wind turbines are covered by the research. The production of the wind turbines and solar panels is more carbon intensive (expressed per generated kWh of electricity) than the production of other conventional power plants, due to the lower electricity output. The overall average GWP per kWh is 0.184kg CO2eq/kWh. Throughout the 2011 this value ranges from a minimum of 0.102kg CO2eq/kWh to a maximum of 0.262kg CO2eq/kWh depending on the timing.