The primary goal of this research is to evolve an economically viable coal and biomass fed energy plant concept that integrates advanced subsystem technologies which are under development in a synergistic manner to generate electricity while capturing a significant portion of the CO2 and coproducing H2 for future fuel cell hybrid vehicle applications. For the design element of the research, a typical plant sire will be conceptualized by taking into account access to coal and biomass feedstock resources, proximity to CO2 sequestration sites and transportation of the coproduct H2. For the purposes of the design study, major subsystems in the context of 2020 deployment will be selected, with development of models for predicting performance. A variety of concepts will be evaluated utilizing system simulation models, and by developing exergy analysis and rough order of magnitude economic analysis leading to a final system design selection. Through a broad array of outreach activities hosted by the principal investigator, including an international colloquium, annual short course events, and industry member meetings, results of the research will be widely disseminated. Additionally, an outreach program will involve local elementary and high school teachers.
with CCS and H2 Co-production World energy consumption is projected to continuously grow in following decades; as a result, emissions of green house gas (GHG) CO2 are expected to increase by significant amount. Coal fired power plants account for approximately 50% of power generation in the United States and approximately 80% of GHG emissions produced by power generation sector. With increasing concerns over global climate changed caused by GHG emissions, carbon capture and storage has become imperative for coal based power plants. Meanwhile, with development and deployment of hybrid vehicles, electric vehicles, and alternative fuel vehicles, GHG reduction efforts in power industry can also benefit transportation sector, which accounts for one-fifth of global CO2 emissions. Power plants with H2 co-production capability can contribute significantly in such development trends because H2 powered fuel cell hybrid vehicles are very promising for future "zero emissions vehicles". Most of H2 co-production power plants investigated to date are based on coal gasification and gas turbine based combined cycle for power generation (IGCC). High temperature fuel cells, such as Solid Oxide Fuel Cell (SOFC) and Molten Carbonate Fuel Cell (MCFC) are highly efficient energy conversion device and integration of coal gasification with high temperature fuel cell, IGFC power plants are very promising for highly efficient utilization of coal for power. High temperature fuel cell systems are also amenable to co-production of H2; however system level investigations of such IGFCs are relatively rare thus far. Besides increasing thermal efficiency, another dimension for GHG reduction is to use feedstock that has low carbon footprint; biomass, a nearly CO2 neutral source of renewable fuel, is an important feedstock of this kind. Much research work has addressed H2 and power production from biomass fuel. However, due to its low energy density (and being a distributed resource), transportation of biomass collected from various locations over long distances to a central plant makes it economically prohibitive. Biomass facility has to be located in close proximity to feedstock, which limits plant size and economies of scale of large plants cannot be taken advantage unless biomass is co-fed with coal to a "central station" type gasification facility located close to biomass sources. Purpose of this work is to investigate thermodynamic performance and cost advantage of employing advanced technologies currently under development for central power plants that (1) employ coal and biomass as feed stock; (2) co-produce power and high purity H2; (3) capture most of CO2 evolved within the plants. Thus, two system designs are developed: the first "base" case is an IGCC system consisting of commercially ready technologies; the second "advanced" case is an IGFC system with large scale SOFCs which are yet to be developed for central power plant applications, currently projected to be demonstrated in the 2020 time frame. Feedstock employed consists of Utah bituminous coal and two typical biomass resources, corn stover and cereal straw. Composition of plant feedstock consists of 66 wt.% of Utah coal, 17 wt.% of corn stover, and 17 wt.% of cereal straw (all on a dry basis). Site ambient conditions correspond to ISO conditions and mechanical draft cooling tower are utilized for plant heat rejection. Both IGCC and IGFC based plants consume same amount of coal and biomass while exporting 154.6 tonne/D of H2 (which is equivalent to 23.41% of input fuel bound energy on an HHV basis), and achieving similar levels of carbon capture (95% to ~98%), but net electricity output of the IGFC case is significantly higher than that of the base IGCC case. The IGCC plant produces 200.64 MW of net electricity, which corresponds to an electricity efficiency (without taking credit for energy contained in exported H2) of 18.51% while the IGFC plant produces as much as 342.80 MW of net electricity with a correspondingly higher electricity efficiency of 31.63% (both on HHV basis), a more than 13 percentage points higher than the IGCC case primarily due to more efficient power block and synergy between hydrogasification process and SOFC. In terms of overall plant efficacy, the IGCC plant can achieve an efficacy of 41.92% while the IGFC plant has an efficacy as high as 55.04%. The IGCC plant cost is lower at $1243 million versus $1440 million for the IGFC plant. However, due to significantly higher efficiency of the IGFC case, revenue stream generated by its larger export power more than compensates for its higher plant cost. Cost of producing coproduct H2 is determined for the two cases using a 20 year levelized cost of electricity of $135/MWh based on data developed by NETL for IGCC and boiler plants fueled by a bituminous coal and equipped with 90% carbon capture. Resulting cost of producing coproduct H2 is significantly lower for the IGFC case, 1178/tonne versus $2620/tonne for the IGCC case.
