# Toward the Decarbonization of Ammonia Production through the Gradual Incorporation of Green Hydrogen

## TL;DR

This paper proposes a method to reduce carbon emissions in ammonia production by gradually incorporating green hydrogen into the Haber-Bosch process.

## Contribution

A novel strategy for integrating green hydrogen into the Haber-Bosch process to reduce fossil fuel use and emissions.

## Key findings

- Green hydrogen can be incorporated up to 60% in the process without violating constraints.
- A partial bypass of the primary reformer prevents overheating in the secondary reformer.
- Steam Methane Reforming is the main source of emissions and the focus of decarbonization.

## Abstract

This
work addresses the decarbonization of the ammonia industry,
which relies almost exclusively on the Haber-Bosch (HB) process and
accounts for more than 1% of anthropogenic carbon dioxide emissions.
The first section of the HB process, the Steam Methane Reforming (SMR),
is identified as the primary target for decarbonization, where fossil
fuels are used as (i) feedstock for hydrogen (H2) production
and (ii) a source for process heat. A methodology is proposed to gradually
incorporate green H2 in the HB process, thus, reducing
fossil fuel intake. The methane-fed HB process is modeled in Aspen Plus, where several process modifications are proposed.
This includes an analysis of the most relevant point of green H2 injection and how to adapt plant operation to satisfy all
process constraints, while minimizing methane consumption. The process
limitations that are subject to this operation strategy were identified
by increasing the green H2 incorporation fraction. The
main bottleneck of this strategy relates to SMR operation, namely
the increase in the secondary reformer’s outlet temperature.
A partial bypass of the primary reformer is suggested to prevent this
unit from overheating. This additional modification proved effective
in controlling the temperature, enabling green H2 incorporation
of up to 60% while satisfying all process constraints.