“Green” Ammonia: Impact of Renewable Energy Intermittency on Plant Sizing and Levelized Cost of Ammonia

Abstract

Ammonia production currently contributes almost 11% of global industrial carbon dioxide emissions, or 1.3% of global emissions. In the context of global emission targets and growing demand, decarbonization of this process is highly desirable. We present a method to calculate a first estimate for the optimum size of an ammonia production plant (at the process level), the required renewable energy (RE) supply, and the levelized cost of ammonia (LCOA) for islanded operation with a hydrogen buffer. A model was developed to quantitatively identify the key variables that impact the LCOA (relative to a ±10 GBP/tonne change in LCOA): levelized cost of electricity (±0.89 GBP/MWh), electrolyzer capital expenditure (±65 GBP/kW), minimum Haber− Bosch (HB) load (±12% of rated power), maximum rate of HB load ramping, and RE supply mix. Using 2025/2030 estimates results in a LCOA of 588 GBP/tonne for Lerwick, Scotland. The application of the model will facilitate and improve the production of carbon-free ammonia in the future.

Techno-economic viability of islanded green ammonia as a carbon-free energy vector and as a substitute for conventional production

“…Each of these alternative methods however, has its own difficulties. Incorporating electrolysis of water using renewable energy with conventional Haber-Bosch synthesis (HB) requires additional flexibility incorporated in plant design (ramping of the HB 13 and a ''hydrogen buffer'' 13,14 ) and optimising power allocation. Electrocatalytic and photocatalytic production, while theoretically having a greater potential, currently have production rates orders of magnitude smaller than required for scale up.…”

“…In this research we further develop the techno-economic model, initially outlined in ref. 13, to enable identification of the optimal plant design, operation and renewable power combination to minimise the achievable LCOA for the islanded production of ammonia using water and air as feedstock. This functionality is then used to calculate and compare the achievable LCOA, optimal plant design and operation for 534 locations in 70 countries for both domestic and multi-national corporations in a present-day and 2030 scenario.…”

Standardizing a unique renewable energy supply chain: the SURESC Model

“…To worsen things, having the highest energy density among all energy carriers is its strength but also his curst, as is highly flammable and thus very dangerous to handle, requiring strong and costly security measures. But all is not lost… Studies suggest that by combining hydrogen with nitrogen present in the air, hydrogen can be stored inside the ammonia compound (NH 3 ), a carbon-free substance that can potentially resolve many of hydrogen negative aspects 55,59,66 . We will analyze ammonia as a sub product of hydrogen later.…”

“…• Ammonia: the base compound for fertilizers is ammonia, which its industrialized process uses fossil-fuels as feedstock for grey hydrogen production, contributing to approximately 1.3% global carbon emissions 66 . Hydrogen production is key for these CO 2 emissions, which we know can be produced by grey, blue and green processes.…”

Poisoning of Ammonia Synthesis Catalyst Considering Off-Design Feed Compositions

“…Therefore, small and simple chemicals with high energy density are required, so that storage and transportation costs are kept low. In recent years, among energy-dense carbon-neutral liquid fuels, ammonia and its production from renewable resources, known as power-to-ammonia, has gained special attention [2,3]. Production of ammonia from renewables has been the subject of many research projects leading to a steep increase in the number of related publications in recent years, as seen in Figure 1.…”