Cement, Energy and Environment

lubricants, chemical feed stocks and alternative liquid fuels such as methanol and dimethyl ether (DME). Why coal to liquid Concerns about the continued supply of affordable crude oil in the future has forced governments and companies to look at the viability of converting coal into liquid fuels. The 1970s saw the first steps in the direction of developing technologies to convert CTL following the global oil crisis. However, the following decade (1980s) saw international oil prices dip and with that the urgency to develop these alternate technologies vanished. Since the late-1 990s, however, coal gasification and Fishcer– Tropsch synthesis have again aroused significant interest because several coal-rich countries have intensified their focus on improving energy secu rity. CTL conversion provides greater energy self– sufficiency and energy security for countries with sufficient coal reserves. The viability of CTL technology is more compelling at a time when crude oil prices are trading at comparatively higher levels and several of the world's oil-rich regions are politically unstable. In a few instances, some countries have to confront the reality of declining domestic crude oil production in the face of increasing domestic consumption. This increases the affected countries' dependency on energy imports. However, the process is very capital intensive in comparison to crude oil refining, and hence requires capital subsidies or other forms of financial support from governments. Environmental concerns have also helped to make coal gasification to top of the mind recall in the international arena, especially with the development of more environmentally benign coal-based technologies in the recent years. The development of clean coal technologies, such as the integrated gasification combined cycle (IGCC) technology, combined with the potential for the commercial storage of concentrated carbon dioxide (C0 2 ), for power generation has led to the availability of processes that are considered to be more environmentally desirable than traditional coal-fired power plants. These clean-coal technologies allow coal-rich countries to benefit from their extensive coal reserves, working with the growing global shift A COlli to Hqu.id plant towards a more environmentally acceptable technologies and processes. Choosing technology In using coal as the feedstock, it is important to remember that coal properties can vary extensively between geographic sites and even within the same region. It therefore, follows that the properties of the targeted coal have a major impact on the choice of a suitable gasification technology. a) Gasification: Coal is fed into giant gasifiers to produce raw gas, which is then purified into the synthesis gas needed for Fischer-Tropsch synthesis. 2