4 research outputs found
Integrating Nuclear Energy to Oilfield Operations -- Two Case Studies
Fossil fuel resources that require large energy inputs for extraction, such as the Canadian oil sands and the Green River oil shale resource in the western USA, could benefit from the use of nuclear power instead of power generated by natural gas combustion. This paper discusses the technical and economic aspects of integrating nuclear energy with oil sands operations and the development of oil shale resources. A high temperature gas reactor (HTGR) that produces heat in the form of high pressure steam (no electricity production) was selected as the nuclear power source for both fossil fuel resources. Both cases were based on 50,000 bbl/day output. The oil sands case was a steam-assisted, gravity-drainage (SAGD) operation located in the Canadian oil sands belt. The oil shale development was an in-situ oil shale retorting operation located in western Colorado, USA. The technical feasibility of the integrating nuclear power was assessed. The economic feasibility of each case was evaluated using a discounted cash flow, rate of return analysis. Integrating an HTGR to both the SAGD oil sands operation and the oil shale development was found to be technically feasible for both cases. In the oil sands case, integrating an HTGR eliminated natural gas combustion and associated CO2 emissions, although there were still some emissions associated with imported electrical power. In the in situ oil shale case, integrating an HTGR reduced CO2 emissions by 88% and increased natural gas production by 100%. Economic viabilities of both nuclear integrated cases were poorer than the non-nuclear-integrated cases when CO2 emissions were not taxed. However, taxing the CO2 emissions had a significant effect on the economics of the non-nuclear base cases, bringing them in line with the economics of the nuclear-integrated cases. As we move toward limiting CO2 emissions, integrating non-CO2-emitting energy sources to the development of energy-intense fossil fuel resources is becoming increasingly important. This paper attempts to reduce the barriers that have traditionally separated fossil fuel development and application of nuclear power and to promote serious discussion of ideas about hybrid energy systems
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HTGR-INTEGRATED COAL TO LIQUIDS PRODUCTION ANALYSIS
As part of the DOE’s Idaho National Laboratory (INL) nuclear energy development mission, the INL is leading a program to develop and design a high temperature gas-cooled reactor (HTGR), which has been selected as the base design for the Next Generation Nuclear Plant. Because an HTGR operates at a higher temperature, it can provide higher temperature process heat, more closely matched to chemical process temperatures, than a conventional light water reactor. Integrating HTGRs into conventional industrial processes would increase U.S. energy security and potentially reduce greenhouse gas emissions (GHG), particularly CO2. This paper focuses on the integration of HTGRs into a coal to liquids (CTL) process, for the production of synthetic diesel fuel, naphtha, and liquefied petroleum gas (LPG). The plant models for the CTL processes were developed using Aspen Plus. The models were constructed with plant production capacity set at 50,000 barrels per day of liquid products. Analysis of the conventional CTL case indicated a potential need for hydrogen supplementation from high temperature steam electrolysis (HTSE), with heat and power supplied by the HTGR. By supplementing the process with an external hydrogen source, the need to “shift” the syngas using conventional water-gas shift reactors was eliminated. HTGR electrical power generation efficiency was set at 40%, a reactor size of 600 MWth was specified, and it was assumed that heat in the form of hot helium could be delivered at a maximum temperature of 700°C to the processes. Results from the Aspen Plus model were used to perform a preliminary economic analysis and a life cycle emissions assessment. The following conclusions were drawn when evaluating the nuclear assisted CTL process against the conventional process: • 11 HTGRs (600 MWth each) are required to support production of a 50,000 barrel per day CTL facility. When compared to conventional CTL production, nuclear integration decreases coal consumption by 66% using electrolysis and nuclear power as the hydrogen source. In addition, nuclear integration decreases CO2 emissions by 84% if sequestration is assumed and 96% without sequestration, when compared to conventional CTL. • The preliminary economic assessment indicates that the incorporation of 11 HTGRs and the associated HTSEs impacts the expected return on investment, when compared to conventional CTL with or without sequestration. However, in a carbon constrained scenario, where CO2 emissions are taxed and sequestration is not an option, a reasonable CO2 tax would equate the economics of the nuclear assisted CTL case with the conventional CTL case. The economic results are preliminary, as they do not include economies of scale for multiple HTGRs and are based on an uncertain reactor cost estimate. Refinement of the HTGR cost estimate is currently underway. • To reduce well to wheel (WTW) GHG emissions below baseline (U.S. crude mix) or imported crude derived diesel, integration of an HTGR is necessary. WTW GHG emissions decrease 8% below baseline crude with nuclear assisted CTL. Even with CO2 sequestration, conventional CTL WTW GHG emissions are 24% higher than baseline crude emissions. • Current efforts are underway to investigate the incorporation of nuclear integrated steam methane reforming for the production of hydrogen, in place of HTSE. This will likely reduce the number of HTGRs required for the process
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PROGRESS TOWARDS MODELING OF FISCHER TROPSCH SYNTHESIS IN A SLURRY BUBBLE COLUMN REACTOR
The Hybrid Energy Systems Testing (HYTEST) Laboratory is being established at the Idaho National Laboratory to develop and test hybrid energy systems with the principal objective to safeguard U.S. Energy Security by reducing dependence on foreign petroleum. A central component of the HYTEST is the slurry bubble column reactor (SBCR) in which the gas-to-liquid reactions will be performed to synthesize transportation fuels using the Fischer Tropsch (FT) process. SBCRs are cylindrical vessels in which gaseous reactants (for example, synthesis gas or syngas) is sparged into a slurry of liquid reaction products and finely dispersed catalyst particles. The catalyst particles are suspended in the slurry by the rising gas bubbles and serve to promote the chemical reaction that converts syngas to a spectrum of longer chain hydrocarbon products, which can be upgraded to gasoline, diesel or jet fuel. These SBCRs operate in the churn-turbulent flow regime which is characterized by complex hydrodynamics, coupled with reacting flow chemistry and heat transfer, that effect reactor performance. The purpose of this work is to develop a computational multiphase fluid dynamic (CMFD) model to aid in understanding the physico-chemical processes occurring in the SBCR. Our team is developing a robust methodology to couple reaction kinetics and mass transfer into a four-field model (consisting of the bulk liquid, small bubbles, large bubbles and solid catalyst particles) that includes twelve species: (1) CO reactant, (2) H2 reactant, (3) hydrocarbon product, and (4) H2O product in small bubbles, large bubbles, and the bulk fluid. Properties of the hydrocarbon product were specified by vapor liquid equilibrium calculations. The absorption and kinetic models, specifically changes in species concentrations, have been incorporated into the mass continuity equation. The reaction rate is determined based on the macrokinetic model for a cobalt catalyst developed by Yates and Satterfield [1]. The model includes heat generation due to the exothermic chemical reaction, as well as heat removal from a constant temperature heat exchanger. Results of the CMFD simulations (similar to those shown in Figure 1) will be presented
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The Technical and Economic Feasibility of Siting Synfuels Plants in Wyoming
A comprehensive study has been completed to determine the feasibility of constructing and operating gasification and reforming plants which convert Wyoming fossil resources (coal and natural gas) into the higher value products of power, transportation fuels, and chemical feedstocks, such as ammonia and methanol. Detailed plant designs, simulation models, economic models and well-to-wheel greenhouse gas models were developed, validated by national-level engineering firms, which were used to address the following issues that heretofore have prevented these types of projects from going forward in Wyoming, as much as elsewhere in the United States: 1. Quantification of plant capital and operating expenditures 2. Optimization of plant heat integration 3. Quantification of coal, natural gas, electricity, and water requirements 4. Access to raw materials and markets 5. Requirements for new infrastructure, such as electrical power lines and product pipelines 6. The possible cost-benefit tradeoffs of using natural gas reforming versus coal gasification 7. The extent of labor resources required for plant construction and for permanent operations 8. Options for managing associated CO2 emissions, including capture and uses in enhanced oil recovery and sequestration 9. Options for reducing water requirements such as recovery of the high moisture content in Wyoming coal and use of air coolers rather than cooling towers 10. Permitting requirements 11. Construction, and economic impacts on the local communities This paper will summarize the analysis completed for two major synfuels production pathways, methanol to gasoline and Fischer-Trosph diesel production, using either coal or natural gas as a feedstock