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TECHNICAL ARTICLE
Figure 3 : Hydrogen fueling components overview . 8
Gas ( GHG ) emissions ; removing it from water results in zero emissions , but it is more expensive and not very energy efficient . Even if the electricity required for the process comes from renewable sources , such as wind or solar , there is still the need to use more energy than what you can obtain with the hydrogen itself . For this reason , some people regard hydrogen production from water as a waste of electricity .
Hydrogen as a Fuel
Hydrogen as a fuel is not something new . “ The National Aeronautics and Space Administration ( NASA ) began using liquid hydrogen in the 1950s as a rocket fuel , and NASA was one of the first to use hydrogen fuel cells to power the electrical systems on spacecraft .” 2 More recently , concerns over climate change have led hydrogen to be touted as a most attractive alternative to less extraterrestrial applications .
Transportation is responsible for more than a quarter of the GHG emissions in the United States , see Figure 1 . The build-up of such gases acts as a sort of blanket around the planet and the resulting heat accumulation is associated with disruptive and unpredictable climate events . One of the ways to reduce GHG emissions from transportation is increasing the number of Zero Emission Vehicles ( ZEVs ). “ There are two types of ZEVs , Battery Electric Vehicles ( BEVs ) and Fuel Cell Electric Vehicles ( FCEVs ). Commercial Success of BEVs has been challenging thus far also due to limited range of very long charging duration .” 4 FCEVs using H 2 infrastructure can be consistently fueled in a safe manner , are fast ( under 5 minutes ) and result in a range similar to conventional vehicles ( 300 + mile range ). In comparison , charging modern BEVs can take anywhere from an hour to 12 hours for a full charge , depending on how full the car ’ s battery is and the type of charging station . 5
Fuel cells ( see Figure 2 ) are more suited for automotive applications than burning H 2 directly ( as in a rocket ). This is because , although hydrogen does not contain carbon , its combustion with air produces oxides of nitrogen , which contribute to the formation of smog and acid rain . Fuel cells operate by converting the chemical energy in hydrogen to electricity , with pure water and heat as the only by-products . As hydrogen and oxygen react across an electrochemical cell , “ energy is released as a combination of low-voltage DC electrical energy and heat . The electrical energy can be used to do useful work directly while the heat is either wasted or used for other purposes .” 7
Hoses for Hydrogen Fueling Stations
From a distance , a hydrogen fueling station look very similar to a conventional one , see Figure 3 ; there is a dispenser and a flexible hose assembly that needs to be connected to the vehicle ’ s tank . However , upon closer inspection , there is a noticeable difference between the hoses .
A hose assembly for hydrogen delivery resembles more of a fire hose than a conventional gasoline fueling one . Hoses for hydrogen are thicker , heavier , and use a nozzle with a locking mechanism ; the reason for this is pressure .
Hoses for gasoline or diesel delivery are rated for a maximum of 10 bar . When attached to the tank , they convey a liquid in a very similar way to how one would pour a glass of water from a jar – if distracted , it is easy to overflow and cause a spillage . In contrast , hydrogen hoses operate with a gas and can handle a much higher pressures ; 350 bar for buses ( and other heavy-duty applications ) and up to 700 bar for light vehicles . In order to accommodate these pressures , the hose requires extensive reinforcement layers ; making it heavier and thicker , see Figure 4 .
Figure 4 : Example of hose cross-section and materials . 9
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