Energy of Hydrogen

Archive for the ‘Delivery of hydrogen’ Category

Hydrogen delivery is another difficulty to ubiquitous utilization of hydrogen. It is closely coupled with not sufficiently developed methods of hydrogen storage. It should be noted that hydrogen delivery is enough dangerous process, since dangerously explosive detonating gas is produced when oxygen from air interacts with hydrogen. Meanwhile, a hydrogen economy requires an infrastructure to deliver hydrogen from where it’s produced to the point of end-use, such as a dispenser at a refueling station or stationary power site.

There are three potential delivery pathways: gaseous hydrogen delivery, cryogenic liquid hydrogen delivery, and novel solid or liquid hydrogen carriers. The liquid and gas pathways transport pure hydrogen in its molecular form via truck, pipeline, rail, or barge. A carrier is a material that carries hydrogen in a form other than free hydrogen molecules.

Transporting gaseous hydrogen via existing pipelines is currently the lowest-cost option for delivering large volumes of hydrogen. The high initial capital costs of new pipeline construction, however, constitute a major barrier to expanding hydrogen pipeline delivery infrastructure.

Today, compressed hydrogen can be shipped in tube trailers at pressures up to about 200 bar. Disadvantages of this method are: the high price and use of 33 kg tanks for 2 kg hydrogen storage, however, and it is cost-prohibitive for distances greater than about 200 miles. Researchers are investigating technologies that might reduce mass of tank to 20 kg for 1 kg hydrogen storage and permit tube trailers to operate at higher pressures (up to 600 bar), which would reduce costs and extend the utility of this delivery option.

Currently, for longer distances, hydrogen is transported as a liquid in super-insulated, cryogenic tank trucks. Gaseous hydrogen is liquefied (cooled to below -253°C) and stored at the liquefaction plant in large, insulated tanks. Over long distances, trucking liquid hydrogen is more economical than trucking gaseous hydrogen because a liquid tanker truck can hold a much larger mass of hydrogen than a gaseous tube trailer. But it takes energy to liquefy hydrogen—using today’s technology, liquefaction consumes more than 30% of the energy content of the hydrogen and is expensive.
Third method is to use for delivery novel liquid or solid hydrogen carriers—which store hydrogen in some other chemical state, rather than as free molecules. Hydrogen extraction from compounds executes by hydrolysis or by thermal dissociation. The first process is one-time process, but the second one makes it possible to create accumulators of many-times. The most significant advantage of novel liquid or solid hydrogen carriers is safety operation. Principal disadvantage is relatively low content of hydrogen.