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Naval nuclear propulsion
Nuclear-powered warships during World War II submarine was found that could be a decisive weapon, but he had a serious problem: their need to emerge after short periods to obtain air for the combustion of diesel engines that were based (the invention of the snorkel improved somewhat the problem but not solved). Admiral Hyman G. Rickover was the first thought that nuclearenergy could help with this problem.
The development of nuclear reactors allowed a new type of engine with key advantages:

1.No need air to the engine operation, and not based on combustion.
2.A small mass of nuclear fuel allows a range of several months (even years) without refueling. For example, U.S. submarines do not require refueling during its lifetime.
3.A motor drive that can matchany other, so that submarines could be built much larger than the existing so far. The largest submarine built to date are the Russian Akula class (48 000 tons displacement, 175 m in length).
These advantages led to ships reaching speeds over 25 knots, they can stay weeks in deep dive and they can also store huge quantities of munitions (nuclear or conventional) in their warehouses. In fact, theU.S. military, France and the UK have only used this submarine propulsion system.
In the submarines have been used pressurized water reactors, boiling water or molten salt. For reducing the weight of fuel in these reactors is used with high levels of uranium enrichment (30 to 40% of the Russians or the Americans 96%). These reactors have the advantage that it is not necessary (although possible)to turn the steam generated by heat into electricity, but can be used directly on a turbine that provides movement to the propellers that drive the ship, dramatically improving performance.
They have built a variety of military ships that use nuclear engines and, in some cases, turn missiles carrying medium or long-range nuclear warheads:

Cruises. As the USS Long Beach (CGN-9), 2 C1W typenuclear reactors built.
Destroyers. As the USS Bainbridge (CGN-25) was the nuclear powered ship ever built smaller, use 2 D2G reactors integrated type.
Aircraft carriers. The most representative is the USS Enterprise (CVN-65), built in 1961 and still operating, using for propulsion type A2W 8 nuclear reactors.
Ballistic submarines. Use nuclear energy for propulsion and missile long-range and mediumweapons. Akula class are of this type, using 2-type nuclear reactor OK-650 and carrying, in addition to conventional weapons, nuclear missiles 20 RSM-52, each with 10 warheads of 200 kilotons each.
Attack submarines. As the USS Seawolf (SSN-21) Seawolf class nuclear reactor that uses an integrated S6W PWR type. It reaches a speed of 30 knots

fuel cell is a device that converts the chemicalenergy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent[1] .
In total there are over 100 fuel cell buses deployed around the world today. Most buses are produced by UTC Power, Toyota, Ballard, Hydrogenics, and Proton Motor. UTC Buses have already accumulated over 970,000 km (600,000 mi) of driving.[80] Fuel cell buses have a 30-141% higher fueleconomy than diesel buses and natural gas buses.[81] Fuel cell buses have been deployed around the world including in Whistler Canada, San Francisco USA, Hamburg Germany, Shanghai China, London England, São Paulo Brazil as well as several others.[82] The Fuel Cell Bus Club is a global cooperative effort in trial fuel cell buses. Notable Projects Include:
* 12 Fuel cell buses are beingdeployed in the Oakland and San Francisco Bay area of California.[82]
* Daimler AG, with thirty-six experimental buses powered by Ballard Power Systems fuel cells completed a successful three-year trial, in eleven cities, in January 2007.[83][84]
* A fleet of Thor buses with UTC Power fuel cells was deployed in California, operated by SunLine Transit Agency.[85]
The first Brazilian hydrogen...
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