Hydrogen has often been touted as the alternative energy with the most promise, but are its limitations too great?
Importance of Energy Source Efficiency
The efficiency of an energy source is usually correlated to many factors that lead to a high usability factor. It can be cheap and easy to extract, simple for transfer, and conditioned for storage. Oil rose to the chief of our energy needs because of its success in these categories. Technologies were built around it, most notably those used for transportation. What was unique about this energy need is that it needed a source that would provide a sufficient amount of energy in an easy transportable size. There had to be an appropriate energy to volume ratio. Oil, usually crafted into gasoline, is efficient in this respect. Yet in the upcoming post-oil world an energy source has to prove itself to be both environmentally and economically sound enough to be used as the primary input for transportation devices. Hydrogen is at the front of this quest for a solution except for its questionable storage possibilities.
Difficulties of Storing Hydrogen Gas
Hydrogen is notoriously hard to contain in a manageable storage device because of its properties as an exceptionally light gas. Its low density means that less energy content can be stored in the same space as another energy source. The same space that could store gasoline would not be able to store an energy equal amount of hydrogen. This presents a problem within automobiles especially because the storage device must be concise enough to fit on the vehicle and have the ability to contain enough energy to give the vehicle a sufficient surplus.
Storing Hydrogen Chemically Not Yet Possible
Chemical storage is a process in which hydrogen is drawn out through chemical reactions between outside substances. There are many proposed compounds to be used in this process, but most often it is supposed to involve hydrides and water. Other suggested chemicals for this process have been methanol and ethanol, but it's debatable if another type of renewable fuel should be used when generating the hydrogen. It is difficult to know whether this is actually a practical solution because the technology won't be ready until 2010-2015, but many government agencies are obviously in favor of it.
Comparing Energy Levels Between Hydrogen and Gas
The hydrogen to oil comparison shows that hydrogen is quite notably more energy rich than oil, yet the density is of prime factor in its failure next to gasoline within current technology. The storage device for 1 kg of hydrogen is huge. Liquid Hydrogen is only 7% as dense as water and has 2.7 times more energy per mass than gasoline. Its low density ends up meaning that you need about four times the storage size for the same amount of energy in comparison to oil. With this requirement for massive system of storage it is difficult to understand how a commercial version could be produced for domestic vehicles.
Gas Compression Technology & Safety
There are two proposed solutions to the issue of hydrogen being less dense, both involving ways of condensing the hydrogen as well as creating conducive storage instruments. Hydrogen can be compressed into tanks designed for containing extremely high pressure. This would be difficult and costly due to how much larger the tank would have to be and the risks involved in pressurizing the hydrogen itself. A tank with that kind of pressure is a volatile risk which could be a possible disaster in a hold. Carbon annotates is one of the more popular ideas connected with the storage debate. The tubes are microscopic tubes of carbon that contain the substance in pores on and within the tube. They can store an immense content of hydrogen, even being quoted at holding up to 65% their body weight in hydrogen.
This estimate is at odds with what the U.S. Department of Energy has defined as safe use for transportation, which is 6.5% it's body weight. This is the minimum containment percentage quoted by researchers, and the only one that government officials have stated is acceptable. Without much more research the usability of this technology is less than optimistic. In the same vain as the nanotubes are glass microspheres, which are glass spheres that are warmed and filled with pressurized hydrogen. Then the glass is cooled which secures the fuel in the globe. When it is reheated by the control device the hydrogen is released for use by the cell. This is much safer than many of the other mentioned storage devices because the pressure is much lower than the rest and the sealability reduces the risk for contamination from outside elements.
Time and Money Costs
There are proposed storage plans from all angles, from those mentioned to that of freezing methods and varieties of compressors. Either way the technologies needed to make any of these workable in a consumer market are years away from being finished at even the most liberal estimates. To make this a viable solution there needs to be more money and time dedicated to research and development.