The project Hidrocat is being developed at Instituto Superior Técnico and aims to offer an emission-free alternative for sea tourism activities and recreation on inland water plans, and medium to short sea shipping.

The project consists of a boat or small ship with electric propulsion and energy sources which can be completely renewable. The setting is in a double-hulled (catamaran), which optimizes energy consumption and reduce the generation of waves and the associated effects of erosion on the banks of inland water surface.

The electric propulsion system is hybrid because it uses energy sources such as solar radiation and hydrogen stored on board. Solar energy is renewable and hydrogen can also be obtained from renewable sources, so the vessel can complete its operation using only renewable energy. The propulsion system comprises propellants of two groups, one in each hull. Each power pack has the electric motor coupled to the propeller, a hydrogen fuel cell and a pressure tank to store hydrogen, photovoltaic panels installed on the roof, a battery system, and a unit of distribution and management of energy flows between the various components of the propulsion system.

Hydrogen, with fuel cells, is used to produce electricity efficiently and cleanly. The use of fuel cells at low temperature completely eliminates local pollutant emissions. The only product that results from generating electricity from hydrogen and oxygen is pure water.

It is hoped that the concept of the vessel described here will be used in environmentally sensitive areas, water plans that are reservoirs for human consumption, and in canals and water plans within or in the vicinity of cities. Some countries already have laws prohibiting the use of combustion engines in water plans more sensitive ecologically (electric only lakes). Moreover, the future European regulations (European Water Framework Directive) requires a progressive protection and environmental improvement of rivers, lakes, estuaries and coastal waters by the year 2015, which will contribute to the successful implementation of the proposed technology.

The main advantages of this system compared to conventional engines are:

  • Total absence of polluting emissions;
  • High comfort of propulsion noise and without vibration;
  • Reduced operating costs for fuel because of the efficient utilization of solar energy;
  • Ability to work only with energy from renewable sources.

The initial cost of the propulsion system is higher than conventional combustion systems, but operating costs are much lower than fuel, so the initial investment is recovered quickly. The cost of electricity to charge the batteries during the night is about 2 Euros. The batteries provide a few hours of operation. Additionally, the solar panels provide much of the energy consumption of the vessel on days of good sunlight.