8.3.3 Discuss the relative advantages and disadvantages associated with the transportation and storage of fossil fuels.

OIL

Transportation of oil
Whether oil is transported from production sites to the refineries by maritime or terrestrial routes, the main issues are those of safety, security and respect for the environment.
Maritime Transportation
The majority of oil transported by maritime means reaches their destination. For example, in the period 2000/2004, according to the accident statistics of ITOPF (International Tanker Owners Pollution Federation) almost 99.99998% of oil transported arrived at its destination without problem.
The organization of maritime transport of oil is complex and many companies and skills are involved in a voyage (building and maintaining the boat, inspecting it regularly, choosing the crew, deciding the route to be taken …).

The petroleum industry has chosen to favor maritime transport for its products, for reasons of greater flexibility.
At sea, the relative disadvantages derive from the possibilities of oil spills and discharging of polluting products such as the residue from tank and bilge cleaning.
Land Transportation
Overland transport by pipelines brings oil, destined for transport by ship, to a port. In the industrialized countries, there are major pipeline networks transporting crude to refineries situated inland and also handling the finished products coming out of the refineries and destined for major centers of consumption.
Normally there are no serious oil spillages. In fact, as soon as the pipeline is damaged by accident or sabotage, pumping is stopped and pollution remains limited. But things become more serious if the state of the pipelines is not kept constantly under surveillance. Oil is always corrosive to a greater or lesser extent, because it contains acidic gases. The pipes deteriorate from the inside and if they are not changed in time, they finish by leaking. This problem exists for example in certain areas in Siberia.
The construction of major pipelines crossing several countries requires intense negotiation. Behind these negotiations are questions of the geopolitics of energy requirements and geopolitical questions in general.

Oil Storage in Tanks (Petroleum storage tanks/ oil depots)
Enormous quantities of oil transported are not used immediately. The same is true for a part of the output from refineries, what are called the finished products. The developed countries have realized for a long time now the strategic importance of oil and thus hold stocks of petroleum products (crude and finished products) equivalent to 3 months of import quantities.
An oil depot (sometimes called a tank farm, installation or oil terminal) is an industrial facility for the storage of oil and/or petrochemical products and from which these products are usually transported to end users or further storage facilities. An oil depot typically has tankage, either above ground or underground, and gantries for the discharge of products into road tankers or other vehicles (such as barges) or pipelines.
Oil depots are usually situated close to oil refineries or in locations where marine tankers containing products can discharge their cargo. Some depots are attached to pipelines from which they draw their supplies and depots can also be fed by rail, by barge and by road tanker (sometimes known as "bridging")


COAL
Coal transportation
There are several methods for moving prepared coal from the mine to the markets.
Coal transportation » Railroads
Rail transportation is by far the most common mode of hauling coal over long distances. Roadbed and track requirements and large fixed investment in railcars make rail transport capital-intensive. However, the long life of the permanent assets, relatively trouble-free operation with minimum maintenance, the large-volume shipments that are possible, the high mechanical efficiencies that are obtained with low rolling resistances, and the dedicated nature of the origin and destination of the runs are some of the factors that make rail transport most attractive for long-term, long-distance, high-volume movements of coal.
Coal transportation » On-highway trucks
If haul distances and shipment sizes are small, it may be advantageous to transport coal by truck through a network of public roads. Advantages over railroads are that trucks can negotiate more severe grades and curves, roads can be resurfaced or constructed more readily and with far lower capital investments than can railways, and the coal flow can be made continuous by adding new trucks and replacing failing trucks.
Coal transportation » Barges
The costs of barge transport depend on the number of barges being towed by a single towboat; this in turn depends on the dimensions of the waterway. Waterways are usually circuitous, resulting in slow delivery times. However, transport of coal on barges is highly cost-efficient.
Coal transportation » Conveyors
Conveyors for carrying coal transport coal from mines to barge-loading stations. In addition, where a power plant is in close proximity to a mine, conveyors are generally used to transport coal to the power plant stockpile. Conveyors can traverse difficult terrain with greater ease than trucks or rail systems, and they can also be extended easily and have the advantage of continuous transport. Conveyors with wide belts and high operating speeds can have enormous capacities, varying from 2,000 to 5,000 tons per hour.
Coal transportation » Slurry pipelines
Coal slurry is a mixture of crushed coal and a liquid such as water or oil.
Slurry pipelines have several advantages. A large portion—approximately 70 percent—of the costs involved in a slurry pipeline are invested in the initial construction of the line and pumping stations and are fixed for the life of the pipeline. Therefore, the total costs of moving slurry during the life of the line do not increase in proportion to inflation. The advantage over rail and truck transport is clear, as the costs of these latter modes escalate with inflation. Furthermore, pipelines require less right-of-way, much less labour, and about half of the steel and other supplies required for other transport methods.
On the other hand, slurry pipelines involve potential environmental problems. Water requirements are substantial: almost one ton of water is needed to move one ton of coal—an important issue in Australia and the western United States, where water supplies are scarce and its availability cannot be guaranteed. Other concerns focus on water pollution at the mouth of the pipeline as well as along its length. For this reason, efforts to obtain right-of-way to lay a pipeline have often faced legal and environmental challenges.

Coal Storage
Coal stockpile is the most common form of coal storage.
Stockpiles
A simple stockpile is formed by machinery dumping coal into a pile, either from dump trucks, pushed into heaps with bulldozers or from conveyor booms. More controlled stockpiles are formed using stackers to form piles along the length of a conveyor, and reclaimers to retrieve the coal when required for product loading, etc.
Taller and wider stockpiles reduce the land area required to store a set tonnage of coal.
Larger coal stockpiles have a reduced rate of heat lost, leading to a higher risk of spontaneous combustion.
Coal-Stockpile.jpg
Coal stockpile



NATURAL GAS
Once natural gas has been extracted from the ground, it is usually transported by pipeline to a refinery, where it is processed.
After processing, the natural gas is transported through pipelines to communities and other markets.
Natural Gas Transportation
Unlike oil, the gas is in a gaseous state at normal pressures and temperatures. This means that, for the same quantity of energy, it occupies a volume 600 times greater than that of oil. Chartering vessels to transport gas in its gaseous state would thus cost … 600 times too much!
Transportation by gas pipelines are less costly and are thus more common. There are underwater gas pipelines, such as those which link Norwegian gas fields to European terminals or those linking North Africa to Sicily. And of course, overland gas pipelines like those that bring Russian gas to the European Union. These gas pipelines are not visible: for reasons of safety and security they are buried underground. The compressed gas circulates at high speed in a gas pipeline, with the aid of compression plants positioned at regular intervals along the network.
But in certain cases the construction of gas pipelines is technically impossible or too expensive, for example to bring Nigerian gas to Europe, or to take gas from Qatar to Japan. To resolve this problem, a method of maritime transport based on the liquefaction of the gas (LNG, liquefied natural gas) and transporting this LNG via maritime means has been introduced.


Natural Gas Storage
Once natural gas reaches its market, gas companies often store it so that enough remains available for peak customer demand. When gas stored underground is needed, it is pumped back to the surface.
The most important type of gas storage is in underground reservoirs. There are three principal types: depleted gas reservoirs, aquifer reservoirs and salt cavern reservoirs.

Depleted Gas Reservoir

These are the most prominent and common form of underground storage. They are the reservoir formations of natural gas fields that have produced all their economically recoverable gas. The depleted reservoir formation is readily capable of holding injected natural gas. Using such a facility is economically attractive because it allows the re-use, with suitable modification, of the extraction and distribution infrastructure remaining from the productive life of the gas field which reduces the start-up costs. Depleted reservoirs are also attractive because their geological and physical characteristics have already been studied by geologists and petroleum engineers and are usually well known. Consequently, depleted reservoirs are generally the cheapest and easiest to develop, operate, and maintain of the three types of underground storage.
Typically, these facilities are operated on a single annual cycle; gas is injected during the off-peak summer months and withdrawn during the winter months of peak demand.

Geographically, depleted reservoirs are relatively close to gas markets and to transportation infrastructure (pipelines and distribution systems) which will connect them to that market as the fields were at one time productive and connected to infrastructure.

Salt Formation

Salt caverns allow very little of the injected natural gas to escape from storage unless specifically extracted. The walls of a salt cavern are strong and impervious to gas over the lifespan of the storage facility.
Salt caverns cannot hold the large volumes of gas necessary to meet base load storage requirements. Deliverability from salt caverns is, however, much higher than for either aquifers or depleted reservoirs. This allows the gas stored in a salt cavern to be withdrawn and replenished more readily and quickly. This quick cycle-time is useful in emergency situations or during short periods of unexpected demand surges.
Although construction is more costly than depleted field conversions when measured on the basis of dollars per thousand cubic feet of working gas, the ability to perform several withdrawal and injection cycles each year reduces the effective cost.

Aquifer Reservoir

Aquifers are underground, porous and permeable rock formations that act as natural water reservoirs. Usually these facilities are operated on a single annual cycle as with depleted reservoirs. The geological and physical characteristics of aquifer formation are not known ahead of time and a significant investment has to go into investigating these and evaluating the aquifer’s suitability for natural gas storage.
If the aquifer is suitable, all of the associated infrastructure must be developed from scratch, increasing the development costs compared to depleted reservoirs.

Aquifers are generally the least desirable and most expensive type of natural gas storage facility.


*Blue means advantages; red means disadvantages.


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