Hydrogen as a Fuel of the Future

Jules Verne appears to be one of the earliest people to recognize, or at least articulate, the idea of splitting water to produce hydrogen (H2) and oxygen (O2) in order to satisfy the energy requirements of society. As early as 1874 in The Mysterious Island, Jules Veme alluded to clean hydrogen fuels, writing  

At ambient temperature and pressure hydrogen is colorless, odorless, tasteless and nontoxic. However, leaks of hydrogen (or any gas for that matter) can displace oxygen and act as an asphyxiant. Any atmosphere with less than 19.5% oxygen by volume in considered oxygen deficient and asphyxiation can lead to physiological hazards. 

The amount of thermal radiation (heat) emitted from a hydrogen flame is low and is hard to detect by feeling (low emissivity). Most commercially available combustible gas detectors can be calibrated for hydrogen detection. Typically alarms from these sensors are set by the manufacturer between 10%-50% of the lower flammability limit (LFL) of hydrogen to avoid the presence of an unwanted flammable environment. 

It is often confusing to know which heating value to use when dealing with similar processes such as electrolysis and fuel cells. The appropriate heating value depends on the phase of the water in the reaction products. When water is in liquid form, the HHV is used if water vapor (or steam) is formed in the reaction, then the LHV would be appropriate. An important distinction is that water is produced in the form of vapor in a fuel cell as well as in a combustion reaction and, therefore, the LHV represents the amount of energy available to do work. Table 4 shows both the LHV and the HHV for common fuels. 

Obviously, the most important virtue of using hydrogen as a fuel is its pollution-free nature. When burned in air, the main combustion product is water with O2 in a fuel cell to directly produce electricity the only emission is water vapor. Indeed this 

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Metallic membranes for hydrogen separation can be of many types, such as pure metals Pd, V, Ta, Nb, and Ti binary alloys of Pd, with Cu, Ag, and Y Pd alloyed with Ni, Au, Ce, and Fe and complex alloys of Pd alloyed with more than one metal [3], Body-centered cubic metals, for example, Nb and V, have higher permeability than face-centered cubic metals, for instance, Pd and Ni [26-29], Even though Nb, V, and Ta possess a permeability greater than that of Pd, these metals develop oxide layers and are complicated to be used as hydrogen separation membranes [29], Especially, the Pd and Pd-based membranes have in recent times obtained renovated consideration on account of the prospects of a generalized use of hydrogen as a fuel in the future [26], We emphasize on these types of membranes in this chapter. 

Hydrogen is receiving a lot of attention lately as a fuel of the future. We are all aware of the difficulty the world will be facing as our nonrenewable energy resources become depleted. Oil is expected to last, by various estimates, into the early twenty-second century and coal perhaps for another century... 

Hydrogen is highly flammable over a wide range of temperature and concentration. Although its combustion efficiency is truly outstanding and welcomed as a fuel of the choice for the future, it inevitably renders several nontrivial technological challenges, such as... 

In conclusion, model compound studies have contributed valuable information for our understanding of the structure and reactivity of the enzymatic centre by probing the chemical possibilities. But apart from the help in the complete understanding of the catalytic principle, they also point to potential alternatives for functional catalysts, which are needed for the cheap production of hydrogen on a large scale to meet the increased demand expected after its introduction as a fuel in the future (Chapters 9 and 10). 

Hydrogen has been suggested as the fuel of the future. One way to store it is to convert it to a compound that can be heated to release the hydrogen. One such compound is calcium hydride, CaH2. This compound has a heat of formation of —186.2 kj/mol and a standard entropy of 42.0 J/mol-K. What is the minimum temperature to which calcium hydride would have to be heated to produce hydrogen at one atmosphere pressure ... 

FlyPOCEN will explore the limits of using hydrogen as a means of de-carbonising fossil fuels and therefore its potential to bridge to a future hydrogen economy. The aim of the project will be to develop and operate a pilot demonstration plant and prove the feasibility, safety and economics, of carbon capture and sequestration. 

The US is optimistic about the prospects for hydrogen, not just as the transportation fuel of the future, but also for its potential to generate electricity to heat and power our homes and businesses. Bush stated that he considered his US 1.5 billion hydrogen development plan a legacy for future generations and key to the nation s energy security. 

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