Tuesday, July 8, 2008

Hydrogen--Future Vehicle Fuel?

Driven by dwindling fossil fuel and deteriorating global warming, a more sustainable fuel economy will need to come into force in meeting the soaring energy required by virtue of growth of economy and population. Hydrogen fuel has been projected as one of the very promosing fuel economies with stiff competition with methanol, electric,solar, hybirc…etc.

Hydrogen fuel

Hydrogen is not considered a fuel at all as it does not come as a pre-existing source of energy like fossil fuels. Insead, hydrogen is best known as energy carrier, being a method of storing power generated any numbers of ways , such as battery.

PMI (Plus, Minus, Interesting) of Hydrogen fuel

1. Plus: Advantages of the hydrogen economy:

1.1 The elimination of pollution caused by fossil fuels:

When hydrogen is used in a fuel cell to create power, it is a completely clean technology. The only byproduct is water. There are also no environmental dangers like oil spills to worry about with hydrogen.

1.2 The elimination of greenhouse gases:

If the hydrogen comes from the electrolysis of water, then hydrogen adds no greenhouse gases to the environment. There is a perfect cycle -- electrolysis produces hydrogen from water, and the hydrogen recombines with oxygen to create water and power in a fuel cell provided that energy for electrolisis is generated by renewable sources such as wind turbine.

1.3 The elimination of economic dependence:

The elimination of oil means no dependence on the Middle East and its oil reserves.

1.4 Distributed production:

Hydrogen can be produced anywhere that you have electricity and water. People can even produce it in their homes with relatively simple technology.

2. Minus: Technological hurdles

2.1 Two major issues concerned:

2.1. 1 Production of hydrogen is usable form. This requires energy input.
2.1.2 Transporting, distributing and storing hydrogen due to its low volumetric energydensity at ambient conditions: One-third of that of methane. Even when the fuel is stored as a liquid in a cryogenic tank or in a pressurized tank, the volumetric energy density (megajoules per liter) is small relative to that of gasoline.

2.2 Limitation of hydrogen fuel:

2.2.1 Because of the energy required to compress or liquefy the hydrogen gas, the supply chain for hydrogen has lower well-to-tank efficiency compared to gasoline.

2.2.2 Compressing the gas requires energy, and compressed hydrogen contains far less energy than the same volume of gasoline. However, technology is advancing progressively. For example, hydrogen can be stored in a solid form in a chemical called sodium borohydride. This chemical is created from borax (a common ingredient in some detergents). As sodium borohydride releases its hydrogen, it turns back into borax so it can be recycled.

2.2.3 Construction of a network of hydrogen stations and the transportation infrastructure will not be developed around it until there is a storage technology that clearly dominates the marketplace. For instance, if all hydrogen-powered cars from all manufacturers used sodium borohydride, then a station network could develop quickly.

2.2.4 There might also be a technological breakthrough that could rapidly change the direction fuel economy. For example, if an inexpensive rechargeable battery with high capacity and a quick recharge time is created, electric cars would not need fuel cells and there would be no need for hydrogen on the road. Cars would recharge using electricity directly.

Once both of these questions are answered in an economical way, the hydrogen economy will be in place. Technological breakthrough is the determining key for Hydrogen fuel prospect.

3. Current facts:

3.1. The common internal combustion engine, usually fueled with gasoline (petrol) or diesel liquids, can be converted to run on gaseous hydrogen. However, the more energy efficient use of hydrogen involves the use of fuel cells and electric motors. Hydrogen reacts with oxygen inside the fuel cells, which produces electricity to power the motors. A primary area of research is hydrogen storage, to try to increase the range of hydrogen vehicles, while reducing the weight, energy consumption, and complexity of the storage systems.

3.2. A potential advantage of hydrogen is that it could be produced and consumed continuously, using solar, water, wind and nuclear power for electrolysis of water. Currently, however, hydrogen vehicles utilizing hydrogen produce more pollution than vehicles consuming gasoline, diesel, or methane in a modern internal combustion engine, and far more than plug-in hybrid electric vehicles. This is because, although hydrogen fuel cells generate no CO2, production of the hydrogen using reforming of fossil fuel creates additional emissions.While methods of hydrogen production that do not use fossil fuel would be more sustainable,currently such production is not economically feasible, and diversion of renewable energy (which represents only 2% of energy generated) to the production of hydrogen for transportation applications is inadvisable.

3.3. Efficiency as automotive fuel:

3.3.1. Hydrogen fuel :thermal energy efficiency of roughly 60% .
3.3.2. Gasoline: Well-to-tank 80 % efficient, requires less energy input at the refinery, and comparatively little energy is required to transport it and store it owing to its high energy density per gallon at ambient temperatures.
3.3.3. The most efficient distribution however is electrical, which is typically 95% efficient. Electric vehicles are typically 3 to 4 times as efficient as hydrogen powered vehicles.

Source: http://en.wikipedia.org/wiki/Hydrogen_fuel

4. Interesting: Methanol economy

4.1 Methanol economy advantages compared to a hydrogen economy:

4.1.1 Efficient energy storage (by volume) and also by weight as compared with compressed hydrogen, when hydrogen storage vessel is taken into account. The volumetric energy density of methanol is considerably higher than liquid hydrogen, in part because of the low density of liquid hydrogen of 71 grams/liter. Hence there is actually more hydrogen in a liter of methanol (99 grams/liter) than in a liter of liquid hydrogen, and methanol needs no cryogenic container maintained at a temperature of -253°C.

4.1.2 Required hydrogen infrastructure would be prohibitively expensive. Methanol can use existing gasoline infrastructure with only limited modifications.

4.1.3 Can be blended with gasoline (for example in M85, a mixture containing 85% methanol and 15% gasoline).

4.1.4 User friendly. Hydrogen is volatile and requires high pressure or cryogenic system confinement.

Source: http://en.wikipedia.org/wiki/Methanol_economy

5. Controversy

Source: http://www.efcf.com/reports/E04.pdf

Type of car and corresponding Power plant-to-wheel efficiency

Fuel cell car operated on compressed gaseous hydrogen 22%
Fuel cell car operated on liquid hydrogen 17%
Advanced diesel-fuelled vehicle 25%
Battery-SOFC (Solid Oxide Fuel Cell) hybrid vehicle and Diesel fuel 33%
Electric car with regenerative braking 66%

The table indicates that the best option for local driving could be the electric commuting car with limited battery capacity for local runs. This might imply the introduction of a new mobility concept, but it does not require the creation of a hydrogen infrastructure. Family cars for longer trips would most likely become battery hybrids. Fuel cells or clean and efficient IC (internal combustion) engine operated on biofuels could serve as range extender. But pure hydrogen is unlikely to be used for this purpose because of the known storage problems the synthetic fuel is not suited for long distance travel. Biofuels are more likely to provide the energy for range extension. The vision would suggest electric power for local and synthetic liquid hydrocarbons for distant travel.
Statements claiming hydrogen fuel cell vehicles to be the best solution for the future transportation applications certainly need further validation. With respect to atmospheric pollution the two alternative options presented above are as benign as hydrogen fuel cells. However, both promise to have a much higher overall efficiency and economy. This is one of the mandates for the outgoing fossil fuel era and for a future Renewable Energy Economy.

"Hydrogen provides an ideal energy solution," said Daryl Wilson, President and CEO of Hydrogenics. "We believe that hydrogen will play a critical role in capturing the power of renewable resources and creating viable clean energy systems that are cost effective, sustainable and environmentally friendly. Hydrogen power is highly scaleable and ideal for storing large amounts of energy for long periods of time. In addition, hydrogen is multi-use and can be used to fuel vehicles and other industrial equipment, or even generate power for community electrical grids, with energy derived from renewable resources", added Wilson

Source: http://www.foxbusiness.com/story/markets/industries/energy/hydrogenics-supply-electrolyer-fuel-cell-renewable-hydrogen-research/-1907503865

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