The purpose of this work is to quantitatively compare the energy cost of design alternatives for a process to produce ammonia (NH3) from air, water, and renewable electricity. It is assumed that a Haber–Bosch (H–B) synthesis loop is available to produce 1000 metric tons (tonnes) of renewable NH3 per day. The overall energy costs per tonne of NH3 will then be estimated at U.S.$195, 197, 158, and 179 per tonne of NH3 when H2 is supplied by (i) natural gas reforming (reference), (ii) liquid phase electrolysis, (iii) solid oxide electrolysis (SOE) of water only, and (iv) simultaneous SOE of water and air. A renewable electricity price of U.S.$0.02 per kWh electric, and U.S.$6 per 10^6 BTU for natural gas is assumed. SOE provides some energy cost advantage but incurs the inherent risk of an emerging process. The last consideration is replacement of the H–B loop with atmospheric pressure chemical looping for ammonia synthesis (CLAS) combined with SOE for water electrolysis, and separately oxygen removal from air to provide N2, with energy costs of U.S.$153 per tonne of NH3. Overall, the most significant findings are (i) the energy costs are not substantially different for the alternatives investigated here and (ii) the direct SOE of a mixture of steam and air, followed by a H.–B. synthesis loop, or SOE to provide H2 and N2 separately, followed by CLAS may be attractive for small scale production, modular systems, remote locations, or stranded electricity resources with the primary motivation being process simplification rather than significantly lower energy cost.
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Valorization of Shale Gas Condensate to Liquid Hydrocarbons through Catalytic Dehydrogenation and Oligomerization
The recent shale gas boom has transformed the energy landscape of the United States. Compared to natural gas, shale resources contain a substantial amount of condensate and natural gas liquids (NGLs). Many shale basin regions located in remote areas are lacking the infrastructure to distribute the extracted NGLs to other regions—particularly the Gulf Coast, a major gas processing region. Here we present a shale gas transformation process that converts NGLs in shale resources into liquid hydrocarbons, which are easier to transport from these remote basins than NGL or its constituents. This process involves catalytic dehydrogenation followed by catalytic oligomerization. Thermodynamic process analysis shows that this process has the potential to be more energy efficient than existing NGL-to-liquid fuel (NTL) technologies. In addition, our estimated payback period for this process is within the average lifetime of shale gas wells. The proposed process holds the promise to be an energy efficient and economically attractive step to valorize condensate in remote shale basins.
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- Award ID(s):
- 1647722
- PAR ID:
- 10092412
- Date Published:
- Journal Name:
- Processes
- Volume:
- 6
- Issue:
- 9
- ISSN:
- 2227-9717
- Page Range / eLocation ID:
- 139
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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