FuelCell
Fuel Cells
There are several fuel-cell technologies that combine hydrogen and oxygen to produce electricity. The oxygen required for a fuel cell comes directly from the air. The hydrogen is not so readily available. It is difficult to distribute and store.
The electricity is used to turn a shaft motor, just like in a diesel-electric system. Current devices the size of a small piece of luggage can power a car.[1][2] As fuel-cell technology improves, fuel cells may well be widespread in marine use. They are already powering submarines and yachts.
However, there are no practical alternatives to diesel fuel for ocean-going boats because of the need to fill up at a fueling station and store highly compressed (and explosive!) hydrogen.
On the horizon for sea transportation are two promising fuel-cell technologies: Proton Exchange Membrane Fuel Cell (PEMFCProton Exchange Membrane Fuel Cell) and Direct Methanol Fuel Cell (DMFCDirect Methanol Fuel Cell).[3] They operate at a fairly low temperature (50-100 °Cdegree Celsius, SI unit of temperature and 50-200 °C, respectively) compared to other fuel cell technologies, warm up quickly and don't require expensive containment structures.
DMFC fuel cells use a reformer to generate the hydrogen from some other fuel, such as methanol (wood alcohol). Methanol used to be distilled from wood but today is usually processed from natural gas. Methanol is stored at atmospheric pressure, usually in a mild steel tank.[4]
AAmpere (amp), SI unit of electrical current basic fuel cell is about 80%percent efficient at producing electricity. DMFCs are around 40% efficient.[5]
But methanol reformers and fuel cells in combination are only about 30-40% efficient, so the overall efficiency drops to 24 to 32%, given a conservative electric motor efficiency of about 80%.
Another approach generates hydrogen from the electrolysis of water, using electricity generated from solar panels or wind turbines. This would make a boat completely independent of shore-based energy, but it is unlikely that a boat could support a sufficiently large installation of green energy generators.
References
- ↑ Union of Concerned Scientists, http://www.ucsusa.org/clean-vehicles/electric-vehicles/how-do-hydrogen-fuel-cells-work
- ↑ Green Car Reports, http://www.greencarreports.com/news/1088626_hydrogen-fuel-cell-cars-to-come-from-toyota-hyundai-honda
- ↑ Center for Renewable Energy & Sustainable technology, http://solstice.crest.org/hydrogen/hydrogen_fuelcell_intro.html
- ↑ Methanol Institute, http://www.methanol.org/health-and-safety/frequently-asked-questions.aspx
- ↑ Center for Renewable Energy & Sustainable technology, http://solstice.crest.org/hydrogen/hydrogen_fuelcell_intro.html
