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.
Some see hydrogen gas as the clean fuel of the future â generated from water and returning to water when it is oxidised. Hydrogen-powered fuel cells are increasingly being seen as âpollution-freeâ sources of energy and are now being used in some buses and cars. Hydrogen also has many other uses. In the chemical industry it is used to make ammonia for agricultural fertiliser (the Haber process) and cyclohexane and methanol, which are intermediates in the production of plastics and pharmaceuticals. It is also used to remove sulfur from fuels during the oil-refining process.