# Off-Grid System for Production of Green Hydrogen via Electrolysis of Industrial Effluents: A Technical Analysis

## TL;DR

This study shows an off-grid system using solar and wind energy to produce green hydrogen from industrial wastewater can significantly reduce emissions and natural gas use.

## Contribution

The novel contribution is a technical analysis of an off-grid green hydrogen system using industrial effluents and renewable energy in Brazil.

## Key findings

- The system produced 17,976 kg/year of hydrogen with 10% blending reducing natural gas use by 3%.
- Environmental benefits included a 10.99% reduction in CO2 emissions (465.5 tCO2eq/year).
- Effluent conditioning delivered 486.8 m3/year, but only 27% reached the electrolyzer due to purification losses.

## Abstract

This study evaluates,
through simulation, the technical
feasibility
and highlights the environmental benefits of a proposed off-grid system
for electrolytic green hydrogen production using industrial effluents
and solar photovoltaic and wind energy (Off-Grid GH2PS).
The simulations compare the operational dynamics of the current scenario
(grid electricity and natural gas) of an industry located in northeastern
Brazil with those of the proposed system (renewable electricity, PEM
electrolyzer, effluent conditioning system, battery storage, and hydrogen–natural
gas blending). The results show strong solar–wind complementarity,
with irradiance ranging from 4.77–6.92 kWh/m2/day
and wind speeds from 5.04–8.49 m/s, resulting in a total generation
of 1.91 GWh/year, of which 62% came from solar energy. Of this amount,
the electrolyzer consumed 1.36 GWh/year (84% of the demand). Hydrogen
production reached 17,976 kg/year, and annual consumption totaled
17,262 kg. The 10% hydrogen blending into natural gas reduced natural
gas use by 3%, but it required a 6.5% increase in volumetric flow.
Effluent conditioning showed low seasonal variability and delivered
486.8 m3/year, although only 27% reached the electrolyzer
due to purification losses. It was observed that 27.54 kgH2O/kgH2 and an energy consumption of 75.90 kWh/kgH2 were required. Environmental performance showed an emission
reduction of 10.99% (465.5 tCO2eq/year). Overall, the Off-Grid
GH2PS demonstrates a strong potential for industrial decarbonization
in regions with high availability of renewable resources and effluents.
Finally, future studies should incorporate high-resolution temporal
data sets, integrate degradation models for system components, and
enable dynamic coupling between water treatment and the energy–hydrogen
subsystems. A detailed life-cycle assessment is also recommended to
strengthen the overall sustainability analysis, as well as an economic
feasibility evaluation of the proposed system.