Techno-Economic Analysis on an Electrochemical Non-oxidative Deprotonation Process for Ethylene Production from Ethane
This report has been prepared as part of a study for Light Water Reactor Sustainability (LWRS) program to evaluate the technical and economic feasibility of integrating a light-water reactor (LWR) nuclear power plant (NPP) with an electrochemical, nonoxidative deprotonation (ENDP) process for production of ethylene from ethane. Process synthesis and modeling were utilized to assess the economic feasibility. ENDP is a novel, early TRL (~1-2) process for producing ethylene and hydrogen via the electrochemical dehydrogenation of ethane. It is currently being demonstrated at the laboratory scale at Idaho National Laboratory (INL). Ethane is a plentiful feedstock that is separated as a condensate during natural gas processing. The U.S. LWR NPP fleet is facing increasing financial challenges due to the expansion of solar and wind power, as well as the low price of natural gas. Alternative strategies are being sought to increase the revenues of NPPs and to find new applications for NPP heat and electricity during periods of overgeneration. NPPs enable solar and wind generating-capacity buildout by providing carbon-free baseload capacity needed for times when solar and wind are unable to generate. Overgeneration occurs during periods when excess electricity is generated due to high solar- or wind-energy output. During these times, NPPs are either paying to curtail wind and solar power or are flexibly operating by turning down their reactor power and generation output. Flexible operations can have impacts on NPP fuel cycles and maintenance while also decreasing revenue. An NPP could alternatively provide carbon-free energy for process-heat steam, cooling water for cooling duties, and house-load electricity to industrial processes, such as ENDP, as an alternative revenue-generating source. In conventional chemical processes, energy and utilities are generated by utilizing fossil fuels, such as coal, fuel oils, and natural gas, resulting in significant emissions of carbon dioxide greenhouse gases (GHGs). Ethylene production via the current industry-standard process of steam cracking, for example, is energy intensive and uses large furnaces burning large amounts of natural gas to “crack” feedstocks from ethane and naphtha to heavy-gasoils into lighter olefinic molecules (such as ethylene, propylene, etc). Steam cracking is a mature and optimized industrial process, but remains both capital and energy intensive. Thus, the steam-cracking process is the subject of frequent process-intensification studies to reduce the process-energy demand. The primary purpose of this report is to present a scaled modeling and techno-economic analysis (TEA) of the novel ENDP process for producing ethylene and hydrogen from ethane. This TEA provides the related chemical process and economic analysis for the production of ethylene and hydrogen via the ENDP process and compares it with conventional industrial steam cracking of ethane for ethylene production. Given that the ENDP process is still in the early research stage, two ENDP cases are evaluated in this study: the projected current case 1 and the predicted future case 2. Case 1 is based on current results obtained from laboratory results on button cells. Case 2 is a predicted future case assuming improvements to the ENDP process are made. The results are compared with those of a reference conventional steam cracking process. The main difference between the two ENDP cases is the single-pass ethylene yield. It is 13% in current case versus 40% in future case at 500 °C operation temperature. The future case assumes that reasonable improvements to the ENDP process will be made in order to enable higher ethane conversion and ethylene yield. Results shows the overall energy and mass balance for the ENDP future predicted Case 2 integrated with a 1000 MWe NPP. For an ethane feed of 111 metric ton (tonne) per hour, the ENDP plant produces 84 tonne/hour ethylene, 7 tonne/hour of hydrogen and a stream of 20 tonne/hour of other C₃ to C₄ hydrocarbons which can be sold as a co-product stream. This process requires 280 MWe power, 49 MWt steam, and 26 MWt cooling duty from an NPP, and 52 MWt of refrigeration duty. The ENDP future case exhibits several advantages over traditional steam cracking, including a 50% reduction in capital costs, a 20% decrease in operating costs, a 77% reduction in process-energy required, and a more than 70% reduction in carbon footprint. For the ENDP future case with an internal rate of return (IRR) of 12% and a selling price of ethylene at $0.44/kg ($0.2/lb), the anticipated net present value (NPV) for this project is $270 MM and the discounted payback period is eight years of operation. It is worth noting that the current industrial ethylene selling price is near $0.44/kg ($0.2/lbs) which is a historically record low price. When the NPV is set equal to zero at an IRR of 12%, the minimum selling price (MSP) of ethylene is $0.37/kg for Case 2. This MSP is the price at which the project will break even, which is 48% lower than that of steam cracking ($0.71/kg), indicating a promising economic feasibility when compared to the conventional steam-cracking process. The high MSP of the steam-cracking process is mainly due to its high capital costs ($1,110M), which are more than three times higher than that of the ENDP future case.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- DOE Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1643942
- Report Number(s):
- INL/EXT-19-56936-Rev.000; TRN: US2201562
- Country of Publication:
- United States
- Language:
- English
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