CCC/182 ISBN 978-92-9029-502-0

April 2011

copyright © IEA Clean Coal Centre

Abstract

This report discusses the current status of utilisation of low quality coals worldwide. The largest

market for low quality coals is power generation. Power generation using low quality coals is

dominated by Pulverised Coal Combustion (PCC) plants. Although the majority of PCC plants uses

subcritical technologies, a number of new plants have adopted supercritical steam conditions at large

scale. Germany currently leads the way in developing high efficiency large-scale supercritical PCC

technology for low rank coals. China and the USA are also developing supercritical PCC technology

rapidly for low rank coals. Circulated fluidised bed combustion (CFBC) is, by the nature of its design,

very suitable for burning low quality coals for power generation or cogeneration. This technology has

been chosen for several repowering projects in Poland and the USA. China now has the largest

number of CFBC units, and the 300 MW class CFBC has been rapidly deployed in that country. There

is very limited experience with IGCC fuelled by low rank coals, and the major challenges are to

increase the plant availability and to lower the capital and operating costs. Coal-to-liquids (CTL)

emerges as an important sector in recent years due to concerns revolving security of energy supply

and high oil/gas price volatilities. Currently, South Africa has the greatest experience with indirect

CTL, while China is rapidly increasing its knowledge base through its large-scale demonstration

projects of both direct and indirect CTL. There is also significant interest in CTL in Australia,

Indonesia, Japan and the USA. Underground coal gasification (UCG) has the potential for tapping into

large, otherwise inaccessible, coal reserves. Australia and South Africa lead the way in developing

advanced UGC technologies that build on developments in directional drilling and computer drilling.

Drying, cleaning and upgrading of low rank coals are of great importance for increasing the use of

low rank coals, as these make the coals cleaner, safer for transport and storage, and more valuable as

an exportable fuel. To this end, a number of high efficiency processes are under development in

Australia, Germany, Japan and the USA. All these developments in power generation, CTL, UCG,

drying and upgrading are likely to ensure a sustainable future for low quality coals.