A futuristic view of nuclear supported coal-to-liquid - 15400

The paper reports the outcomes of a study aimed at improving the carbon efficiency of the Fischer Tropsch synthesis process. It is assumed that nuclear energy is available to a Coal-to-Liquid (CTL) process through any combination of the following energy carriers: steam, electricity, hydrogen, oxygen and/or high temperature helium. Various High Temperature Reactor (HTR) Nuclear supported CTL (NCTL) process schemes were investigated with the aid of 'plug-and-play' process building blocks. The latter included CO₂ lean gasification, Plasma Arc Reforming (PAR) and nuclear hydrogen using a thermo-chemical water splitting process (hereinafter HyS). Alternative NCTL schemes were evaluated in terms of their carbon efficiency, capital intensity and economic feasibility. These solutions were then compared against an existing conventional 80.000 barrels (bbl) per day facility located in Secunda, South Africa. The study reached three important conclusions: First, although the capital intensity (overnight cost per barrel per hour) of a conventional CTL plant can be reduced from 6.8 m/bbl/h to 2.1 m/bbl/h (dollars) if nuclear hydrogen was available, this advantage is cancelled by the increase in capital intensity of the combined CTL/HTR/HyS system, to values far beyond that of a conventional CTL plant. As a consequence it was necessary to increase the selling price of synthesized products (by assuming a higher crude oil price) to make these configurations economically viable. Secondly, a HTR plant with temperature top-up to deliver heat to a HyS plant at 800 Celsius degrees, producing 1.46 kg/sec hydrogen in support of a CTL process, has a small economic viability window, even at oil prices in excess of 150 dollar/barrel. Hence it is not worth pursuing. Thirdly, a VHTR (Very High Temperature Reactor) plant capable of delivering heat to a HyS plant at 950 C. degrees, producing 2.2 kg/sec hydrogen in support of a CTL process, has a reasonable economic viability window when the oil price is above 150 dollar/bbl. (authors)