Progress towards sustainable cities already includes different types of environmentally friendly fuels such as electricity, hydrogen, biobutanol or gas. Cost, along with the levels of pollution it can contribute to the environment, is one of the keys to ensuring its evolution and integration.

Ecological fuels are those that do not come from oil, as is the case with traditional fuels, but from primary sources that ensure respect for the environment by reducing emissions in the production process. The aim is to promote and encourage different ways of studying its proper development, since the origin of electricity (coal or renewable energies) is the key to reducing pollution levels.

Among the most relevant ones, we highlight :

-Hydrogen: this is one of the first energy sources that car manufacturers began to develop years ago. The operation of this type of vehicle is based on the use of a fuel cell in which hydrogen oxidizes and produces electricity. Although its production is not entirely natural, its impact (0.3%) would still be lower than that of oil (1%).

-Electricity: it also operates using a fuel cell. It is a more accessible source and the long-term objective is to obtain it naturally through wind power, a very rich resource in Spain. Although there are still variables to be improved, the difference in terms of emissions compared to diesel or petrol is remarkable.

-GNL (from biomass to liquid): this is a renewable fuel that, during the combustion process, produces a minimum level of pollution. It is another form of recycling that also reduces waste.

-GNL (Gas to Liquids): is a synthetic source made from natural gas through a chemical combustion process.

In the sustainability cycle, in addition to fuels, the lifecycle of vehicle manufacturing will be a very important variable to take into account. A study carried out by Ademe estimates how the manufacture of the latter still causes pollution indices, but they are nevertheless much more favourable in terms of gas emissions and the ratio to fossil resources.

These types of fuels result from a common need: to create more sustainable forms of mobility.