Performance of a Small-Scale Haber Process: A Techno-Economic Analysis

Abstract

In this work, the techno-economic analysis of a 20,000 metric ton (MT) green ammonia production facility is presented. This facility is 30 times smaller than a large-scale conventional process, producing ammonia from totally renewable resources: hydrogen from water electrolysis and nitrogen from pressure swing adsorption. Two different configurations of the Haber–Bosch (HB) process are investigated: high-pressure reaction-condensation (RXN-CON) and low-pressure reaction-absorption (RXN-ABS). Process simulation was implemented using ASPEN Plus, where the reactor and absorber columns were designed as a custom model. The results obtained were then used to estimate the total capital and operating costs. The high-pressure processing improves the single-pass conversion and loop efficiency but relies on costly compression, whereas the low-pressure processing is more favorable for both capital and operating costs. The performance analysis of the HB process indicates that the operating pressure affects ammonia production costs. The levelized cost of ammonia (LCOA) from our small-scale Haber process was found to be about twice more expensive than the conventional commodity ammonia prices. Our sensitivity analysis suggests that inherently safer low-pressure RXN-ABS can be utilized for thermochemical energy storage of renewable resourcesfor scenarios that numerous small ammonia plants can be implemented in areas with local ammonia demand, with access to excess renewable electricity at the time of high penetration of renewable resources. Under such conditions, the LCOA from this plant can be comparable with the ammonia commodity prices. When the revenue from selling oxygen is considered into economics, small-scale all-electric ammonia can be profitable with an after-tax rate of return of 27.50% for RXN-ABS.

Green ammonia as a spatial energy vector: a review

“…A third approach is the use of grid 73,74,85,90,98 or hydro 76,97 electricity to entirely supply the electrolyser and ammonia plant at almost all times, or whenever renewables are not available. Although this approach enables maximum value to be extracted from the installed capital equipment, and no costs to be allocated to hydrogen storage, it demands the use of either of hydroelectricity, whose global potential is far less than global demand, 99 or of prohibitively expensive grid electricity, which is not generally decarbonized.…”

Application of Liquid Hydrogen Carriers in Hydrogen Steelmaking

“…NH 3 is separated out from the recycle loop via condensation at −25 to −33 • C, which necessitates refrigeration [88,89]. The need for refrigeration provides another reason for the high reactor pressure in the Haber-Bosch process: a lower pressure would lead to unpractically low NH 3 condensation temperatures [90].…”

Rapid pressure swing adsorption for small scale ammonia separation: A proof‐of‐concept

“…For lower pressure manufacturing (150 bar), a refrigeration system is required to achieve the lower condensation temperature necessary to condense ammonia. [ 10 ] Since gas compression and refrigeration are two major contributors to the total energy consumption in ammonia manufacturing, there is a critical need for designing separation processes that reduce the process energy consumption. [ 2,10,11 ] One approach can be to replace phase‐changing separation with a more energy‐efficient unit operation.…”

“…[ 10 ] Since gas compression and refrigeration are two major contributors to the total energy consumption in ammonia manufacturing, there is a critical need for designing separation processes that reduce the process energy consumption. [ 2,10,11 ] One approach can be to replace phase‐changing separation with a more energy‐efficient unit operation. It is widely accepted that exploiting separations which obviate the phase‐changing can lead to energy savings up to one order of magnitude.…”

“…[ 21 ] Some of the recent efforts toward enhanced ammonia synthesis have been dedicated to low‐pressure ammonia manufacturing that can reduce capital and operating costs. [ 10 ] Recently, an innovative, but simple, reaction‐absorption process is proposed that enables ammonia production at 10–20 times lower pressure while producing ammonia at rates comparable to those of conventional process operating at high pressure. [ 22,23 ] A major feature of the absorption‐based separation is that the absorber column, which is packed with metal halide absorbents, can separate ammonia more completely at significantly lower ammonia concentrations.…”