Nuestra NEBRIJA 30 - julio 2019

34 Nebrija Research Group in Vehicle Engineering Recovering energy We are dedicating a lot of effort in looking for al- ternatives to our energy sources. The contribu- tion of renewable energies in transport increases, but only very slightly: from 7.1% in 2016 to 7.2% in 2017. It is well be- low the target of 10% set for 2020 under the EU's Renewa- ble Energies Directive. Only two member states (Austria and Sweden) have reached the 10% target. Vehicles in which energy is stored in a battery or in hy- drogen tanks combined with a fuel cell are brea- king through at a slower pace than expected. In this transition period, the adaptation of combus- tion engines so that they can work with gas, be it compressed natural gas, liquefied natural gas or liquefied petroleum gas, is proposed as a prag- matic solution. It is not possible to summarize in a just few lines the advantages and disadvantages of the various solutions, given that the answers depend heavily on how electricity is obtained in each country (and if indeed this generation of energy is really a "renewable" source), and the so- lution adopted will depend on macropolitical and strategic decisions. However, regardless of the source of energy that is adopted, we must think about the efficiency of the system that converts ener- gy -in the case of transport- to drive the vehicle. It is relevant to bring up a study published by the United States Department of Energy that concludes that between 12-30% of the energy that is introduced in the form of fuel is used to move the car, and the rest dissipates into the different parts of the vehicle. It is therefore not difficult to understand the impor- tance of recovering part of this energy. In order to recover energy in a vehicle, the options are technologies focused on the recovery of ther- mal energy, mainly of the engine, of the kinetic energy of the vehicle in braking, of the mechani- cal energy of tire deformations, of engine vibra- tions. and the mechanical energy of suspension systems. In the Nebrija Research Group in Vehicle Engi- neering, we focused on the recovery of mecha- nical energy in suspension systems and the ther- mal energy lost mainly in exhaust gases. These Between12and30%of theenergy that is introduced in the form of fuel in a car is used to move it, while the rest dissipates into the different parts of the vehicle. Hence the importance of recovering part of that energy. W e must be aware that we cannot waste natural resources as if they were infinite Nebrija Research