The definition of coal energy
This is a form of energy which emanates from below the surface of the ground. It is a very potential source of energy which results from remains of the decayed plant and animal life (Coal Association of New Zealand, 2009). These fossils are usually buried deeply over a long period of time ranging in millions of years. The vegetative matter which has been compressed finally forms what is called peat. As time progresses, peat is gradually transformed to coal. The fact that the initial materials which form coal were alive at first, it is also referred to as fossil fuel similar to other forms of fuels like petroleum products. The main composition of coal is carbon and it generates what is known as coal energy.
Energy generated from the burning of coal cannot be renewed. This implies that coal sources can be used until depletion because it is a finite energy resource which is non renewable.
Coal production in New Zealand
The key source of energy in New Zealand is coal. This energy resource has provided this country with supply for energy which is well assured of even in times when hydroelectric power generation is low. The coal produced in New Zealand is not just used for domestic consumption. It is also exported to other destinations. The high quality bituminous coals have high demand in the foreign markets. The amount or content of sulphur in this form of coal is rather low. The very sample of coal has also high swelling ability. As a result, they have varied uses especially in steel manufacturing industries. Moreover, they can be well blended.
In 2009 alone, a total of 4.6 million tonnes of coal was produced in New Zealand. Although this seemed to be a remarkable production, it was characterized by a slight decline of about seven per cent (Solid energy New Zealand ltd, 2002). This production was classified into three categories. Firstly, there was the bituminous coal which accounted for 2.09mt. The other classification was the lignite coal which was about 0.26mt of the total production and finally sub-bituminous coal which was 2.22mt. Both the opencast and ground mines are used to extract these three categories of coal. However, the opencast mine has been the main method of mining coal compared to ground mines.
One of the reasons why the production of coal declined during this period was that there was an industrial action which hampered the mining process at the main mining grounds.
There were four underground mines which were in operation by 2009. At the same period, opencast mines which were actively operating were 18. Much of the production in 2009 was carried out by Solid Energy. The national production of coal was mainly centred in Stockton and Rotowaro. In addition, some mining processes also takes place in West Coast and Waikato.
Coal reserves in New Zealand
There is about 15 billion tonnes of coal reserve in New Zealand today. About 52 per cent of this estimated reserved quantity is under the economically recoverable classification (Coal Association of New Zealand, 2009). The South Island which also hosts the Otago area is well known for the production of lignite which is of low grade. Additionally, this form of coal accounts for only 8 per cent of the total production of coal in New Zealand.
The Solid State is the largest producer of coal and is entirely owned by the state to assist in the production of this commodity in the 45 recognised mining points spread across New Zealand. The company carries out mining activities for and on behalf of the state. As mentioned earlier, Waikato is the chief location of the coal mines and is the main provider of coal in New Zealand steel and other manufacturing industries. The mines which are located at the south mainly provide coal supplies to suffice the needs of the domestic industries while the West Coast reserves are mainly meant for export purposes (Solid energy New Zealand ltd, 2002).
The geology of coal mining and production processes in New Zealand is carried out by Crown Minerals. It has the mandate of documenting the potential of coal mining in New Zealand, the properties as well as the classification of the coal mined. Reports which are relevant for the purposes of tracking down the supply of this form of energy are also kept by Crown Minerals. In cases where exploration of the resource is needed, all the documented facts are carried out and kept by Crown Minerals. Accounts on coal field geology have been published by the Institute of Geological and Nuclear Sciences among other organisations. The reports are very important as far as the study, exploration and mining of coal resources in New Zealand is concerned.
Coal energy uses in New Zealand
The main use of coal in New Zealand is in the production of electric energy. Additionally, it is also used as process energy in the domestic industrial plants. About 3.1mt of coal was used domestically in 2009 which marked a significant drop of 27 per cent in consumption. The main reason for this drop was an equal decline of coal fire production at Hunty. About 4 per cent of New Zealand consumption of energy was catered for by coal as a source of energy (Morris, 1997). The reason why coal has been preferred to other sources of process energy like gas is that it is relatively cheap. For instance, electricity or diesel supplies may be very expensive when used as process energy in industrial plants. At the local level, Glenbrook steel mill is one of the largest users of coal especially as a source of process energy. The Hunty power station is also another heavy domestic consumer of coal. The dairy industry is also dependent on coal as one of the cheap and reliable sources of energy where it is used for the purposes of providing energy needed in the processing of daily products. For example, pasteurisation is a process which requires significant of energy and coal comes in handy for this application. Timber production in the lumbering industry has also used coal as the chief source of energy. Further, the health sector also depends on coal in the provision of energy which has often been regarded as not only reliable but also affordable. Hunty alone has the capacity of providing 20 percent of the energy resources derived from coal.
Coal is also an important foreign exchange earner in New Zealand owing to the fact that the commodity is exported to other locations. For instance, a total of 2.09mt of coal was exported from West Coast in 2009. This was the bituminous type. Some of countries which import coal from New Zealand are USA, South Africa and India. The amorphous form of coal exported is that which is mainly composed of coke although the specially graded coal like lignite is also exported. The state owned company which is responsible for the mining process of coal in New Zealand produces about 95 percent of the total coal earmarked for export (Morris, 1997). The remaining amount is catered for by Francis Mining. The sample of coal which has low ash content is especially preferred for use in the making of steel. This type is produced in Pike River and it is relatively hard compared to other forms of coal. This hard coking coal is also exported due to high demand in the international market.
Advantages of coal
One of the advantages of coal is that it can burn with a lot of ease and release significant amounts of energy which is required for movement especially in industrial processes. This energy can also be converted easily to electricity. In addition, coal is relatively available in most locations of the world making it possible for different countries to access it (Eden, 1981). This makes it to be largely inexpensive compared to oil or gas. Moreover, coal energy resources make it possible to generate significant quantities of electricity within a short period of time. If water is used in the generation of the same, it may take a longer time to produce the same amount of power. It is also possible to generate this electric energy in one confined location compared to hydroelectric power generation. A fossil fuel station used to generate power can be located at any location as long as means of transportation has been catered for to transport the coal products.
Disadvantages of coal
Although coal has its advantages, there are also some disadvantages which come along with the mining and usage of this energy resource. For instance, it cannot be renewed hence it is a non-renewable energy resource (Eden, 1981). As a result, coal may be depleted from the mines. In cases where coal has to be transported, it may prove to be very costly bearing in mind that it is a bulky product. It requires an elaborate transport system in addition to storage facilities for easy management. Storage is of great importance especially if energy production is to be sustained throughout the year.
One of the hotly debated issues is that of global warming. Coal, just like other fossil fuels generates carbon dioxide when it undergoes combustion. This is the most potential greenhouse gas which catalyses the process of global warming. Hence, continued production and consumption of coal is not environmental friendly and unless this is controlled, it may lead to serious environmental threats in future. Further, by-products which are harmful in nature are produced in the course of combustion leading to pollution of air. One such toxic product released form the combustion of coal in insufficient air is carbon monoxide. It may lead to suffocation and death of the victim when inhaled (Trinnaman, 2004).
Coal mines often leads to complete change of the environment and destroys the existing ecosystem. This damage cannot be reversed. Besides, when coal is burnt in the atmosphere, it releases carbon dioxide which is left suspended for considerable length of time. This in turn leads to acid rain during precipitation causing damage to both plant and animal tissues. The aquatic environment also develops into extreme acidity which jeopardises the aquatic life. There are some plant and animal species which may not survive in an acidic environment.
In spite of these pollution factors, it is not possible to recycle the waste products from the combustion of coal and its compounds. Also, those who work in coal mines encounter numerous accidents each year especially in cases where precaution is not taken in advance. Such deaths are hardly experienced in the process of tapping other sources of energy like hydropower.
Coal energy technologies
In order to convert coal energy to usable electricity, the integrated gasification combined cycle technology is often used (Eden, 1981). It is one of the most thorough and environmentally sustainable methods which have been adopted in the conversion process. The electric power stations which make use of coal gasification technology is used in New Zealand. This technology has also been considered to be the best option in future because it will enable clean conversion of coal to electricity.
The principle behind coal gasification is the disintegration of coal using heat energy into its constituent chemical elements instead of direct combustion of the mined product. Steam is directed towards coal and regulated amounts of oxygen follow. The physical conditions of temperature and pressure are equally kept high during this process. As a result, the molecules which make up coal are broken down which is then followed by a series of reactions generated chemically. Finally, hydrogen, carbon monoxide and other gases are produced (Trinnaman, 2004). On the other hand, the stream cycle receives the surplus heat which has been generated during the process of combustion. This is synonymous to what happens in a combined cycle gas turbine. There is a high level of efficiency achieved using this technique than the traditional burning of coal to generate energy.
References
Coal Association of New Zealand (2009). New Zealand Coal Production, Reserves, and Use. Web.
Eden, J. R. (1981). Energy economics: growth, resources, and policies New York: Cambridge University Press.
Morris, L (1997). The New Zealand Coal Industry Enterprise, Wellington: New Zealand Trust.
Solid energy New Zealand ltd (2002). Solid Energy Coals of New Zealand. Web.
Trinnaman J. (2004). Survey of energy resources World Energy Council, London: Elsevier Inc.