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Technology demonstration of large-scale photo-electrochemical system for solar hydrogen production

Periodic Reporting for period 3 - PECSYS (Technology demonstration of large-scale photo-electrochemical system for solar hydrogen production)

Reporting period: 2020-01-01 to 2020-12-31

Solar driven hydrogen generation via water electrolysis is an archetypal use of renewable energy that ensures a sustainable energy supply while minimising green-house emissions. The challenges for adaptation by society are the high cost of the technology and maintaining the reliability of supply compared to conventional energy supply from fossil fuels. Thus the specific objectives of the project are:
• To study and develop devices for integrated photo-electrochemical concepts and scale viable concepts to prototype size > 100 cm².
• To use socio-techno-economic analysis to predict and select concepts with levelised cost of hydrogen (LCOH) production below € 5/kg.
• To scale the prototypes of the less mature but promising technologies to a demonstrator with active area > 10 m².
• To achieve a hydrogen production of 16 gH2/h from the demonstrator resulting from a solar to hydrogen conversion efficiency (ηStH) of at least 6 %.
• To ensure that the initial solar to hydrogen conversion efficiency of the demonstrator does not reduce by more than 10 % relative after six months of continuous operation.
Two system concepts were considered in the project.
In the first, representing, the next generation of solar hydrogen generation systems, photovoltaic (PV) modules were both directly electrically coupled to and thermally integrated with alkaline electrolysers using earth abundant electrocatalysts. A CuInGaSe photovoltaic mini-module with a total collection area of 100 sq. cm was integrated to an alkaline electrolyser at Uppsala University, Sweden. This prototype achieved a maximum ηStH 13.5 % under 1000 W/sq. m illumination with an H2 generation rate of 3.7 g/h/sq.m on an active area 82.2 sq. cm basis). Also, a scalable 64 sq.cm aperture area device consisting of triple-junction thin-film silicon solar cells coupled with a bifunctional NiFeMo catalyst was developed at Forschungszentrum Jülich (FZJ, Germany). This device achieved an ηStH of 4.5% with an area specific H2 production rate of 1.56 g/h/sq.m.
Additionally, a silicon heterojunction (SHJ) photovoltaic module was thermally integrated with an alkaline electrolyser and scaled-up from 294 cm² to 2600 cm² solar collection area at Helmholtz Zentrum Berlin (Germany). Thanks to insights from the analysis of the outdoor performance of the smaller device, the heat transfer between the PV module and the electrolyser in the larger prototype, increased leading to a 34% relative improvement in ηStH to 5.1 % at 1000 W/m². Under these conditions, the scaled-up prototype achieved an H2 generating capacity of 85 mL/min at an area specific rate of 1.56 g/h/sq.m.
In the second concept, PV modules were directly coupled to proton exchange membrane (PEM) electrolysers to form a modular generation unit. This layout is unique because the balance of plant was minimised by feeding water to the electrolyser from the cathode side only using hydraulics and not pumps as well as by eliminating both power management electronics and active heating/cooling of the electrolyser. At Consiglio Nazionale delle Ricerche (Catania, Italy), the effects of bifaciality were studied on a 730 sq.cm SHJ bifacial PV module that was directly electrically coupled to a single PEM electrolyser cell. The albedo effect of ~ 30% combined with a bifacial factor of 90 %, increased the ηStH, by 17% relative, to 13.5% compared to a mono-facial SHJ PV mini-module with an average production rate of 4.2 g/h/sq.m.
The final Project outdoor demonstrator installed at FZJ, consisted of a 10 m² array of several units using either CuInGaSe (from Solibro Research AB) or SHJ (Enel Green Power, S.p.A) PV modules. The demonstrator was operated continuously for 9 months (2680 h) before the project ended. In this time a total of 22 kg of hydrogen were collected with an average ηStH of 10% with less than 10% relative degradation, exceeding the respective project targets. The costs and green house impact of this technology can be reduced to levels below 5 €/kg-H2 and below the green hydrogen threshold of 36.4 g CO2. Eq./kg- H2, by improving the energy conversion efficiency, operating the system in sunny regions such as in Southern Europe and /or extending the system lifetime beyond 20 years.
The results of the project are available in open access peer reviewed publications, in public deliverables and on the project website. The consortium plan to scale the directly coupled SHJ PV-PEM electrolysis concept, with a reduced balance of plant, to the 250-kW range. Other results are now used by the partners as background in newer research projects and as additions to course materials in universities.
The PECSYS project results represent progress beyond state of the art in many aspects. Firstly, the outdoor operation of directly coupled of PV modules and electrolysers (with reduced BOP) for 9 months has not been previously published as such tests are usually done for a few hours or days as part of an investigation of conventional PV driven electrolysis. The models used to predict the performance of the system explicitly include the effect of ambient conditions on the temperature and thus the electrolyser- and overall StH efficiency. Using these models allowed an economic and lifecycle assessment on an actual system based on performance measured for real world operation, unlike most reports which consider hypothetical devices. The StH efficiencies achieved for all the approaches are the best in class for devices using the same materials and in the same order of scale.
We envisage several economic, environmental and societal impacts as a result of this project. The availability of such compact modular solar generators would provide a low-cost source of renewable energy. This would encourage local communities and individuals to actively participate in the energy transition towards zero greenhouse emissions as they would benefit from more autonomy regarding decisions about the use and pricing of energy. The new technology opens up possibilities for new business models such as in value added manufacturing for both photovoltaic and electrolyser manufacturers, as well as leasing for utility companies. The new business models many increase employment opportunities for the public in Europe. The reduced environmental impact may reduce the prevalence of related respiratory health issues in the society. Lastly, the variety of scientific knowledge and technical know-how developed in the project shall contribute towards Europe’s position in world leading research and innovation for future energy systems.
Outdoor performance behaviour of a SHJ PV mini-module directly coupled to a PEM electrolyser
Thin film silicon PV mini-module coupled and thermally integrated with an alkaline electrolysis cell
CuInGaSe PV mini-module directly coupled and thermally integrated with an alkaline electrolysis cell
SHJ PV mini-module thermally integrated with an alkaline electrolysis cell scaled 290 cm² to 2600 cm
Enhanced H2 production by using a bifacial SHJ PV mini-module directly coupled to a PEM electrolyser
SHJ PV modules with a PEM electrolyser directly mounted on the rear
PECSYS Project Logo
Demonstrator test bed at Jülich Germany featuring SHJ or CuInGaSe PV modules