Have you ever wondered by how much CO2 emissions can be reduced by running cars electrically or
with hydrogen as fuel? This Brief provides a quantitative answer to this question using the
example of the combined road traffic in Spain. The authors calculate the resulting greenhouse
gas (GHG) emissions for the production of hydrogen gas or the required electricity and
installing and maintaining the necessary infrastructure. In this way they can compare with the
GHG emissions in the present situation of oil fueled cars. Using different scenarios they
obtain an assessment how much 'greener' the electric or hydrogen cars can get.The method
described in this Brief is scalable and readily adaptable to other countries. It can thus be
used for investigating sensible approaches and developing recommendations for a conversion. As
expected the results depend strongly on the production scenarios for hydrogen or electricity
production. The wrong choice can even result in increased GHG emissions. A proper choice of the
roadmap toward a more sustainable and greener future is of greatest importance - the results
described in this Brief can serve as a valuable and useful guide on our way.
