Solar Water Heating for Enhanced Electrolysis in Hydrogen Production

Abstract

As the need to limit the effect of climate change gets stronger, the transition to sustainable energy solutions becomes very important. Solar thermal energy and green hydrogen production represent two quite promising sustainable fields towards decarbonizing industrial processes and energy sectors. This thesis presents an extensive simulation and performance analysis of a solar thermal energy system designed to generate heated water for different kinds of electrolysis, destinated for hydrogen production, which can be combined with captured CO2 and therefore production of electrofuels, such as methanol, whereas in the meantime this process reduces industrial emissions of CO2 in the atmosphere.
The objective of this research is to evaluate technical and operational feasibility of implementing solar collectors for low-temperature electrolysis systems, applied on technical and meteorological data of the 8 MWp solar PV park of Vassiliko, Cyprus. Focusing on technologies applied on modern projects, dynamic simulation models were developed using a widely used simulation software, the Transient System Simulation Tool (TRNSYS). The models’ performance was carried out under dynamic meteorological conditions; to the water flowrate needs and the water temperature configurations. Emphasis was placed, as well, on optimizing solar energy capture by simulating properly wind and infrared solar collectors (WISC) that are applied at the back of solar PV panels, as well as compound parabolic collectors (CPC) based on their technical data. The goal is the generation of 123.000 tons of heated water, at distinct operational temperature ranges, for the production of hydrogen that can contribute to a 10% decrease in the CO2 emissions of a local cement industry, by combining them with hydrogen coming from electrolysis to produce methanol.
The simulation results of various configurations demonstrate that an integrated solar thermal system can effectively maintain required inlet fluid temperature ranges for Proton Exchange Membrane (PEM) and Anion Exchange Membrane (AEM) electrolysis methods. Solar water heating for AEM electrolysis proves to be a less demanding option since it can be processed only by applying collectors at a part of the present facilities of the solar PV park of Vassiliko, whereas the additional required facilities turn out to be less challenging. However, solar water heating for PEM electrolysis seems to be a more stable option in terms of thermodynamic utilization. It was discovered that a layout including two WISC (wind infrared sensitive collector) units in parallel connected in series with one CPC (concentrated power compound) unit presents quite good thermal efficiency and could be implemented at a significant part of the solar PV park, as well as in additional space close to it. By optimizing water mass flow rates and simulating various models, high thermal efficiency can be obtained, making the process thermodynamically viable. Ultimately, this work provides valuable insights and a robust modeling framework for designing the first stage of a sustainable and scalable energy system, whereas it highlights the significance of developing research on various other crucial parts of the project in order to make it highly efficient and environmentally sustainable. Nevertheless, as shown in the next chapters of the thesis, there are many kinds of studies that need to be done with the intention of turning a project like that into reality and evaluating all the impacting factors of an implementation like this.

Popular Abstract

Heated water can boost sustainable hydrogen and methanol production, smoothing our transition away from fossil fuels, by “trapping” heat developed in solar panels using it for water electrolysis, “cleaning up” polluting activities.

By combining retrofit and parabolic solar collectors, we can generate the exact operational water temperature range needed to produce green hydrogen efficiently, paving the way for sustainable fuels that turns our means of transportation into running without demanding more fossil fuels. Climate change demands a radical re-evaluation of how we power our lives. While solar farms are popping up worldwide to “clean up” electricity grids, transportation sectors (like cars, buses, ships and planes) cannot rely on heavily on batteries. This is where electrofuels come in. By capturing carbon dioxide (CO2) directly from gaseous pollutants and combining it with green hydrogen, we can synthesize clean methanol. Methanol is a versatile liquid fuel that fits right into our existing gas stations and car engines without needing expensive upgrades. However, creating the hydrogen quantities required for this process usually takes an immense amount of electrical energy. Surprisingly, a method that can make this process cheaper and more sustainable is simply raising the water temperature. Splitting water molecules becomes much easier and demands less electricity.
This thesis project designed and simulated a smart engineering framework tailored to the sunny, semi-arid climate of Vassiliko, Cyprus. At this site, an existing solar park sits right next to a massive cement plant. The goal is to figure out how to heat 123.000 tons of water per year using solar energy to feed low-temperature water electrolysis systems. This amount of water creates enough hydrogen to react with captured pollutants, decreasing a cement factory's carbon footprint by 10%. Using a powerful computer simulator called TRNSYS, various configurations of solar collectors were tested under real-world weather patterns. Traditionally, water backing is used primarily to cool down solar panels to keep them running efficiently. In this project, the primary goal was to maximize the water's temperature as much as possible for the chemical plant downstream, treating any cooling of solar panels as a welcome bonus. The simulation models tested how well solar loops can heat water for Anion Exchange Membrane (AEM), Proton Exchange Membrane (PEM) and Alkaline electrolysis methods, finding out that the PEM method is the most appropriate one for the specific project. Cyprus suffers from severe freshwater shortages, and consequently the water -used for green fuel production- must come from seawater desalination plants. For these engineering layouts to be truly “green”, future work must ensure the desalination plants themselves are powered by clean energy and not fossil fuels. Moreover, this research provides the initial baseline for the development of similar water heating projects, as well as for a broader circular economy project, proving we can harvest the sun's discarded heat to transform localized industrial pollution into a clean, transportable fuel of tomorrow.

• author: Sarantakis, Alexandros
• supervisor: Narmin Hushmandi
• organization: Department of Energy Sciences
• course: MVKM05 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: solar heating, collectors, electrolysis, water, flowrate, temperature, loop, e-fuel, methanol, solar thermal system, decarbonization
• publication/series: Solar Water Heating for Enhanced Electrolysis in Hydrogen Production
• report number: LUTMDN/TMHP-26/5696-SE
• ISSN: 0282-1990
• language: English
• id: 9240255
• date added to LUP: 2026-06-18 09:25:57
• date last changed: 2026-06-18 09:25:57