Coal Geology

Larry Thomas

• Publisher: Wiley-Blackwell
• Year: 2020
• ISBN:
  9781119424260
• Edition: 3
• Topic: Naturwissenschaften
• Subtopic: Energie

A global exploration of coal geology, from production and use to chemical properties and coal petrology

Coal Geology, 3rd Edition, offers a revised and updated edition of this popular book which provides a comprehensive overview of the field of coal geology including coal geophysics, hydrogeology and mining. Also covered in this volume are fully revised coverage of resource and reserve definitions, equipment and recording techniques together with the use of coal as an alternative energy source as well as environmental implications.

This third edition provides a textbook ideally suited to anyone studying, researching or working in the field of coal geology, geotechnical engineering and environmental science.

• Fills the gap between academic aspects of coal geology and the practical role of geology in the coal industry
• Examines sedimentological and stratigraphical geology, together with mining, geophysics, hydrogeology, environmental issues and coal marketing
• Defines global coal resource classifications and methods of calculation
• Addresses the alternative uses of coal as a source of energy
• Covers a global approach to coal producers and consumers

1
Preview

1.1 Scope

The object of this book remains unchanged. It is to provide geologists and those associated with the coal industry, as well as teachers of courses on coal about its geology and uses, with a background of the nature of coal and its varying properties, together with the practice and techniques required in order to compile geological data that will enable a coal sequence under investigation to be ultimately evaluated in terms of mineability and saleability. In addition, the alternative uses of coal as a source of energy together with the environmental implications of coal usage are also addressed.

Each of these subjects is a major topic in itself, and the book only covers a brief review of each, highlighting the relationship between geology and the development and commercial exploitation of coal.

1.2 Coal Geology

Coal is a unique rock type in the geological column. It has a wide range of chemical and physical properties, and it has been studied over a long period of time. This volume is intended to be a basic guide to understanding the variation in coals and their modes of origin and of the techniques required to evaluate coal occurrences.

The episodes of coal development in the geological column are given together with the principal coal occurrences worldwide. It is accepted that this is not totally exhaustive, as coal does occur in small areas not indicated in the figures or tables.

The reporting of coal resources/reserves is an important aspect of coal geology, and international standards and guidelines are in place to ensure the correct reporting procedures to be undertaken. Most national standards are now being reconciled with these, and the principal resources/reserves classifications are given. Current estimates of global resources and reserves of coal, together with coal production figures, are listed. Although these obviously become dated, they do serve to indicate where the major deposits and mining activities are currently concentrated.

In relation to the extraction of coal, the understanding of the geophysical and hydrogeological properties of coals is an integral part of any coalmine development, and these are reviewed together with the principal methods of mining coal. The increasing use of computer technology has had a profound impact on geological and mining studies. Some of the applications of computers to these are discussed.

An important development in recent years has been the attempts to use coal as an alternative energy source by either removing methane (CH₄) gas from the in‐situ coal and coal mines, or by liquefying the coal as a direct fuel source, or by gasification of coal in situ underground. These technologies together are particularly significant in areas where conventional coalmining has ceased or where coal deposits are situated either at depths uneconomic to mine or in areas where mining is considered environmentally undesirable.

1.3 Coal Use

The principal uses of traded coals worldwide are for electricity generation and steel manufacture, with other industrial users and domestic consumption making up the remainder.

Lack of environmental controls in the use of coal in the past has led to both land and air pollution, as well as destruction of habitat. Modern environmental guidelines and legislation are both repairing the damage of the past and preventing a reoccurrence of such phenomena. An outline is given of the types of environmental concerns that exist where coal is utilised, together with the current position on the improvements in technology in mining techniques, industrial processes, and electricity generation emissions.

The marketing of coal is outlined, together with the contractual and pricing mechanisms commonly employed in the coal producer/coal user situation.

1.4 Background

In most industrial countries, coal has historically been a key source of energy and a major contributor to economic growth. In today's choice of alternative sources of energy, industrialised economies have seen a change in the role for coal.

Originally, coal was used as a source of heat and power in homes and industry. During the 1950s and 1960s cheap oil curtailed the growth of coal use, but the uncertainties of oil supply in the 1970s led to a resumption in coal consumption and a rapid growth in international coal trade. This, in turn, was followed by an increasingly unfavourable image for coal as a contributor to greenhouse gas (GHG) emissions and had been closely identified with global warming. The coal industry has responded positively to this accusation, and modern industrial plants have much lower emissions levels than in previous years. Current figures show that coal accounts for 45% of all carbon dioxide (CO₂) emissions.

The world consumption of fossil fuels, and thus emissions of CO₂, will continue to increase, and fossil fuels still meet around 86% of primary energy requirements. The objective of the United Nations Framework Convention on Climate Change (UNFCCC) signed at the 1992 Earth Summit in Rio de Janeiro is to ‘stabilise GHG concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system’. No set levels were identified, but emissions in developed countries were expected to be reduced to 1990 levels. A series of annual meetings by the international body under the UNFCCC, the Conference of the Parties (COP), have taken place, notably COP‐3 in Kyoto, Japan, in 1997, at which the Kyoto Protocol was drawn up, setting emissions targets for all the countries attending. However, government ministers at COP‐6 in The Hague in November 2000 failed to agree on the way forward to meet the Kyoto Protocol targets. This placed the whole of the Kyoto Protocol's ambitious and optimistic plan for a global agreement on GHG emissions reduction in an uncertain position. This could be an indication of overambitious goals rather than any failure in the negotiations, and it is up to the parties concerned to establish a realistic set of targets for emissions reductions in the future. The Copenhagen Accord in 2009 reinforced the need for emissions reductions, together with providing financial assistance to help developing countries cut carbon emissions. In 2015, at the Paris Agreement, parties to the UNFCCC reached agreement to combat climate change and to accelerate and intensify the actions and investments for a sustainable low‐carbon future. This was the first legally binding global climate deal.

It remains a fact that many economies still depend on coal for a significant portion of their energy needs. Coal currently accounts for 28% of the world's consumption of primary energy, and, importantly, coal provides fuel for the generation of around 39% of the total of the world's electricity. In 2018, internationally traded coal was 1169 Mt, the bulk of which was steam or thermal coal. Globally, 5.6 Gt of coal was consumed in 2016 (BP plc 2017).

Coal reserves are currently estimated to be around 900 Gt, and the world coal reserves to production ratio is nearly six times that for oil and four times that for natural gas. This, together with the globally democratic distribution and secure nature of coal deposits, will ensure that coal will continue to be a major energy resource for some considerable time to come.

With this scenario in mind, this volume is intended to assist those associated with the coal industry, as well as educationalists and those required to make economic and legislative decisions about coal.

The philosophy and views expressed in this book are those of the author and not the publisher.

2
Origin of Coal

2.1 Introduction

Sedimentary sequences containing coal or peat beds are found throughout the world and range in age from middle Palaeozoic to Recent.

Coals are the result of the accumulation of vegetable debris in a specialised environment of deposition. Such accumulations have been affected by synsedimentary and post‐sedimentary influences to produce coals of differing rank and differing degrees of structural complexity, the two being closely interlinked. The plant types that make up coals have evolved over geological time, providing a variety of lithotypes in coals of differing ages.

Remarkable similarities exist in coal‐bearing sequences, due for the greater part to the particular sedimentary associations required to generate and preserve coals. Sequences of vastly different ages from areas geographically separate have a similar lithological framework and can react in similar fashions structurally.

It is a fa...