COPRODUCTION: A GREEN COAL TECHNOLOGY?

摘要

This paper has shown that coproduction could be considered a "green" coal technology because of three very important characteristics: 1. It produces electric power from clean synthesis gas using advanced combined cycle technology at high efficiency. Sulfur is recovered as elemental sulfur rather than being emitted as SOx, NOx is low, and the residual coal ash is transformed into a non-leachable slag. 2. It produces ultra clean transportation fuels that contain zero sulfur, zero aromatics, and have high cetane number. They have been shown to produce significantly less exhaust emissions when used in diesel vehicles than petroleum fuels. 3. The configuration of coproduction produces a concentrated stream of almost pure carbon dioxide that could readily be sequestered once this technology has been developed. From the aspect of economics, as natural gas prices increase beyond $3.75/MMBtu, the lower cost producers will most likely determine the value of electric power. They will be the coal-based IGCC plants. When the price of natural gas is $3.75/MMBtu, the value of electricity is 35.6 mills. This is the required selling price of power from an advanced IGCC plant to realize a 15 percent ROE. In this analysis it is assumed that the electric power value increases with natural gas price until it reaches a value of 35.6 mills. After that, the power value is capped at 35.6 mills/kWh even though natural gas prices continue to increase. The ROE is greater for the all coal coproduction plant than for the IGCC plant at low gas prices. When natural gas prices exceed about $3.75/MMBtu, the ROE for the IGCC plant is similar to the ROE for the coproduction plant if the oil price follows the EIA reference price. However, if the oil price remains in the OPEC target range the all coal coproduction facility has a higher ROE than the IGCC pant for all natural gas prices. Therefore, the all coal coproduction plant would continue to be more economically attractive than an IGCC plant under the OPEC oil price target range.