Design Concepts for Co-Production of Power, Fuels & Chemicals Via Coal/Biomass Mixtures
The overall goal of the program is to develop design concepts, incorporating advanced technologies in areas such as oxygen production, feed systems, gas cleanup, component separations and gas turbines, for integrated and economically viable coal and biomass fed gasification facilities equipped with carbon capture and storage for the following scenarios: (i) coproduction of power along with hydrogen, (ii) coproduction of power along with fuels, (iii) coproduction of power along with petrochemicals, and (iv) coproduction of power along with agricultural chemicals. To achieve this goal, specifically the following objectives are met in this proposed project: (i) identify advanced technology options and innovative preliminary design concepts that synergistically integrate plant subsections, (ii) develop steady state system simulations to predict plant efficiency and environmental signature, (iii) develop plant cost estimates by capacity factoring major subsystems or by major equipment items where required, and then capital, operating and maintenance cost estimates, and (iv) perform techno- economic analyses for the above described coproduction facilities. Thermal efficiencies for the electricity only cases with 90% carbon capture are 38.26% and 36.76% (HHV basis) with the bituminous and the lignite feedstocks respectively. For the coproduction cases (where 50% of the energy exported is in the form of electricity), the electrical efficiency, as expected, is highest for the hydrogen coproduction cases while lowest for the higher alcohols (ethanol) coproduction cases. The electrical efficiencies for Fischer-Tropsch coproduction cases are slightly higher than those for the methanol coproduction cases but it should be noted that the methanol (as well as the higher alcohol) coproduction cases produce the finished coproduct while the Fischer-Tropsch coproduction cases produce a coproduct that requires further processing in a refinery. The cross comparison of the thermal performance between the various coproduct cases is further complicated by the fact that the carbon footprint is not the same when carbon leaving with the coproduct are accounted for. The economic analysis and demand for a particular coproduct in the market place is a more meaningful comparison of the various coproduction scenarios. The first year cost of electricity calculated for the bituminous coal is $\$$102.9/MWh while that for the lignite is $\$$108.1/MWh. The calculated cost of hydrogen ranged from $\$$1.42/kg to $\$$2.77/kg depending on the feedstock, which is lower than the DOE announced hydrogen cost goal of $\$$3.00/kg in July 14, 2005. Methanol cost ranged from $\$$345/MT to $\$$617/MT, while the market price is around $\$$450/MT. For Fischer-Tropsch liquids, the calculated cost ranged from $\$$65/bbl to $\$$112/bbl, which is comparable to the current market price of crude oil at around $\$$100/bbl. It should be noted, however, that F-T liquids contain no sulfur and nitrogen compounds. The calculated cost of alcohol ranged from $\$$4.37/gal to $\$$5.43/gal, while it ranged from $\$$2.20/gal to $\$$3.70/gal in a DOE funded study conducted by Louisiana State University. The Louisiana State University study consisted of a significantly larger plant than our study and benefited from economies of scale. When the plant size in our study is scaled up to similar size as in the Louisiana State University study, cost of alcohol is then reduced to a range of $\$$3.24/gal to $\$$4.28/gal, which is comparable. Urea cost ranged from $\$$307/MT to $\$$428/MT, while the market price is around $\$$480/MT.