During these last years, we have realized about one of the main global issues that involve the current society. Increasing of the temperature, acid rain or the extinction of many ecosystems are an evident sign of the global warming. Taking care and having knowledge about terrestrials cycles, implies that people will know that the only way to reduce the gas emissions is to cut down the human impact on Earth. IMO and EU having seen the increase of the number of container ships, crude fuel oil ships and bulk carrier ships legislated a MRV regulation. They wrote many rules with the goal that vessels of 5000 GT and above design a system that allows the monitoring, reporting and verification fuel oil consumption. The Organisation will publish the annual report, with the purpose of forcing the ship owners to an improvement of energy efficiency. IMO devised two indexes, EEDI and EEOI, that empower the relation between fuel consumption and CO2 emissions. The proposed methodologies are four: BDN, fuel oil tank for the monitoring on board, flow metres and direct emissions monitoring. In this project different variable as well as cost, accuracy and availability of the system are analyzed. Moreover theoretical systems of monitoring, as well as, STEAM-2 and CARB are proposed, and also exposed a new technology called VEEO Mk4 created by Tecnoveritas that allows -through a software- a monitoring of all systems related to fuel consumption on board at any time. Finally, representing a practical analysis through BDN methodology, we get the EEOI value for two different vessels with different dwt.