1 Ajo Bike Barcelona Ajo Bike is a budget bike shop in El Raval, a vibrant district in central Barcelona. 2  You can rent a bike for as little as 4 euro for 2 hours. 3  The price for 24 hours is 10 euro and if you are more people, every extra person pays 9 euro.ne of the most famous and breathtaking locations to visit in Barcelona the most famous building in the entire city and its landmark, La Sagrada Familia. Although incomplete, the church is a UNESCO World Heritage Site, and in November 2010 was consecrated and proclaimed a minor basilica by Pope Benedict XVI.
The main use of hydrogen is to remove the sulfur that occurs naturally in fuels, a process that improves air quality. Sources of fossil energies such as crude oil naturally contain sulfur. The combustion of fuels containing sulfur produces sulfur oxides: SOx. These irritating gases cause a number of serious respiratory ailments.
In years to come, hydrogen itself may become one of the most important fuels for cars as on burning it does not produce carbon dioxide, but there are major problems to be overcome before it can be used in this way, including its manufacture, storage and distribution. Figure 1 Uses of hydrogen.