Abstract
Hydrogen is a key in moving toward a sustainable and green energy sector. Hydrogen production is quickly increasing. To ensure that the hydrogen produced is green, low emission production technologies need to be researched and continuously developed. This thesis reviews the life cycle emissions of two different hydrogen production technologies: alkaline electrolysis and photocatalysis.
Both technologies split water into hydrogen and oxygen. Electrolysis does this using electrical current while photocatalysis utilizes light energy. Electrolysis is a far developed technology with a technology readiness level of 8-9, while photocatalysis is still low on the scale, around 2-4. Currently, comparing the two technologies presents challenges due to these unequal premises.
This thesis found that the best way to produce hydrogen is through alkaline electrolysis, utilizing wind power as the electricity source. Life cycle emissions in this scenario are 0.65 kgCO2eq/kgH2. The second most favorable option is electrolysis using solar PV as the electricity source, with life cycle emissions of 2.90 kgCO2eq/kgH2. Photocatalysis was found to have life cycle emissions of around 2.43 – 4.43 kgCO2eq/kgH2 and 29.3 – 37.7 kgCO2eq/kgH2 using a panel reactor setup and a parabolic concentrator system respectively. When land use does not cause emissions, the parabolic concentrator system can reach life cycle emissions of 4.53 – 9.00 kgCO2eq/kgH2.
Three of the four studied technologies are able to reach the EU standard for green hydrogen, life cycle emissions of 3.38 kgCO2/kgH2. Though currently electrolysis is the most viable way to produce clean hydrogen, the photocatalytic systems have potential to become contenders in the hydrogen production field. Progress in the development of better materials and higher efficiencies would enable industrial-scale plants and increase hydrogen yields lowering the emissions currently estimated.
Both technologies split water into hydrogen and oxygen. Electrolysis does this using electrical current while photocatalysis utilizes light energy. Electrolysis is a far developed technology with a technology readiness level of 8-9, while photocatalysis is still low on the scale, around 2-4. Currently, comparing the two technologies presents challenges due to these unequal premises.
This thesis found that the best way to produce hydrogen is through alkaline electrolysis, utilizing wind power as the electricity source. Life cycle emissions in this scenario are 0.65 kgCO2eq/kgH2. The second most favorable option is electrolysis using solar PV as the electricity source, with life cycle emissions of 2.90 kgCO2eq/kgH2. Photocatalysis was found to have life cycle emissions of around 2.43 – 4.43 kgCO2eq/kgH2 and 29.3 – 37.7 kgCO2eq/kgH2 using a panel reactor setup and a parabolic concentrator system respectively. When land use does not cause emissions, the parabolic concentrator system can reach life cycle emissions of 4.53 – 9.00 kgCO2eq/kgH2.
Three of the four studied technologies are able to reach the EU standard for green hydrogen, life cycle emissions of 3.38 kgCO2/kgH2. Though currently electrolysis is the most viable way to produce clean hydrogen, the photocatalytic systems have potential to become contenders in the hydrogen production field. Progress in the development of better materials and higher efficiencies would enable industrial-scale plants and increase hydrogen yields lowering the emissions currently estimated.
| Original language | English |
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| Qualification | Bachelor Degree |
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| Award date | 18 Apr 2024 |
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| Publication status | Published - 18 Apr 2024 |
| MoE publication type | G1 Polytechnic thesis, Bachelor's thesis |
Funding
This thesis was completed as a part of the project “Climate neutral, justified and sustainable H2 transition” (JustH2Transit) and is funded by Strategic Research Council within the Research Council of Finland, decision 358422.
Keywords
- hydrogen production
- alkaline electrolysis
- photocatalysis
- life cycle emissions