Experimental, computational and environmental impact study of a solar powered hydrogen production system for domestic cooking applications in developing economies

Lead University: Brunel University London

Professor Maria Kolokotroni, Dr Zahir Dehouche, Dr Evangelia Topriska

Collaboration

The University of Manchester: Professor Adisa Azapagic, Dr Ximena C Schmidt Rivera

University of Technology, Jamaica: Dr Earle Wilson

Ho Polytechnic, Volta Region, Ghana: Dr Divine T Novieto

Summary

In many developing economies, a high percentage of domestic energy demand is for cooking based on fossil and biomass fuels. Their use has serious health consequences affecting almost 3 billion people. Cleaner cooking systems have been promoted in these countries such as solar cooking and smokeless stoves with varying degrees of success. In parallel, solar electrolytic hydrogen systems have been developed and increasingly used during the last 25 years for electricity, heat and automobile fueling applications.

This study by Brunel University has developed and tested experimentally in the laboratory a solar hydrogen plant numerical model suitable for small communities, to generate and store cooking fuel. The numerical model was developed in TRNSYS and consists of PV panels supplying a PEM electrolyser of 63.6% measured stack efficiency and hydrogen storage in metal hydride cylinders for household distribution. The model includes novel components for the operation of the PEM electrolyser, its controls and the metal hydride storage, developed based on data of hydrogen generation, stack temperature and energy use from a purpose constructed small-scale experimental rig. The model was validated by a second set of experiments that confirmed the accurate prediction of hydrogen generation and storage rates under direct power supply from PV panels.

Based on the validated model, large-scale case studies for communities of 20 houses were developed. The system was sized to generate enough hydrogen to provide for typical domestic cooking demand for three case-studies; Jamaica, Ghana and Indonesia. The daily cooking demands were calculated to be 2.5kWh/day for Ghana, 1.98kWh/day for Jamaica and 2kWh/day for Indonesia using data mining and a specific quantitative survey for Ghana. The suitability of weather data used in the model was evaluated through Finkelstein Schafer statistics based on composite and recent weather data and by comparing simulation results. A difference of 0.9% indicated that the composite data can be confidently used. Simulations results indicate that a direct connection system to the PV plant rather than using a battery is the optimal design option based on increased efficiency and associated costs. They also show that on average 10tonnes of CO2/year/household can be saved by replacing biomass fuel with hydrogen.

The final part of the study by The University of Manchester analysed, on a life cycle basis, the environmental impact of the system in Jamaica. It compared the results with the currently used cooking fuels and analysed different future scenarios. The results show that the proposed system would reduce climate change by 91% as well as other impacts such as POF, FFD and TET. However, it will also increase metal depletion (MD) and ozone depletion (OD), as well as toxicities to the water, soil, and humans. The primary energy demand (PED), slightly increases by ~5%, but reduces the contribution of non-renewable sources by around 30%. In terms of local health, the study also shows that the proposed technology would significantly improve the air quality, due to the avoidance of the combustion of solid and fossil fuels during the use stage.

Highlights

  • Development of numerical model in TRNSYS validated experimentally in the laboratory
  • Weather data suitability evaluation through Finkelstein Schafer statistics
  • Case studies for communities of 20 houses in Jamaica, Ghana and Indonesia
  • 10tonnes of CO2/year/household can be saved by replacing biomass fuel with hydrogen
  • LCA shows reduction of climate change impact and improvement of indoor air quality

Schematic of the solar hydrogen system

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