Why Clean Energy Still Loses Heat, and How Nanofluids Could Fix It
Clean energy often loses efficiency after heat is generated. Nanofluids offer a practical way to move heat more efficiently, unlocking better performance from existing solar and industrial energy systems.
If solar thermal collectors already reach the right temperatures, why do so many industrial heat systems still lose efficiency at the point where heat is supposed to move, not where it is generated?
And if nanofluids can deliver a 30% thermal conductivity gain at 0.002% volume fraction, what is the real limiting factor for solar thermal and PV cooling deployment, heat transfer physics or manufacturable, stable fluid production at scale?
At the International Conference on Sustainable Energy Systems (ICOSES 2025), Prof. Saleh Khamlich, Associate Professor of Applied Chemistry and Engineering at Mohammed VI Polytechnic University, answered these questions in a talk that framed nanofluids as a practical lever for improving the efficiency of solar thermal systems (photovoltaic cooling, and industrial heat processes) particularly in high-irradiation environments like Morocco.
As he explains, conventional heat transfer fluids are a limiting factor in renewable energy systems. Oils, glycols, and water were not designed for the thermal loads and efficiency demands now placed on solar thermal collectors, concentrated solar power systems, or hybrid PV-thermal installations.
As solar deployment moves beyond electricity generation and into industrial heat, that limitation becomes structural rather than incremental.
Much of Morocco’s energy challenge, he noted, is not electricity generation but heat, a problem similar in plenty of other places globally.
Chemical processing, food and beverage production, mining, textile manufacturing, and materials processing all consume large amounts of thermal energy, often in temperature ranges that are well suited to solar thermal systems. Drying, pasteurization, distillation, cleaning, and low-to-medium temperature process heat account for a significant fraction of industrial energy use, yet remain largely electrified or fossil-based.
He thinks solar thermal systems can address this gap, but only if their efficiency improves. Flat plate collectors and evacuated tubes are suitable below roughly 200 degrees Celsius. Parabolic troughs and Fresnel systems extend that range to 350 or 400 degrees.
In all cases, heat extraction and transport determine whether these systems are viable at industrial scale. That is where nanofluids enter the picture.
Nanofluids, as Khamlich defined them, are conventional heat transfer fluids augmented with suspended nanoparticles.
The premise is simple but powerful. Solids have higher thermophysical properties than liquids and by introducing nanoparticles into a base fluid, thermal conductivity, heat capacity, and overall heat transfer performance can be enhanced without changing the system architecture itself.
At the nanoscale, materials exhibit properties that differ fundamentally from their bulk counterparts. As particle size decreases, surface-to-volume ratio increases, altering thermal, optical, and mechanical behavior. Gold nanoparticles do not behave like gold bars. The same principle applies to metals, metal oxides, and carbon-based materials introduced into fluids.
Khamlich walked through the material landscape with a pragmatist’s eye.
Metallic nanoparticles such as copper and aluminum offer high thermal conductivity and strong performance gains at relatively low volume fractions. Metal oxides provide more modest enhancements but are significantly cheaper and easier to scale.
Carbon-based materials, including carbon nanotubes and graphene-derived structures, offer exceptional thermal performance but remain cost-prohibitive for widespread industrial deployment.
Ah but cost, he emphasized repeatedly, is the gating factor.
Thermal enhancement alone is insufficient. Nanofluids must be manufacturable, stable, and economically viable at scale. This constraint shaped much of his group’s work.
To design nanofluids rationally rather than empirically, Khamlich’s team combines experimental work with molecular dynamics simulations. At the nanoscale, heat transfer is governed by molecular vibration and energy exchange at solid–liquid interfaces. Simulations show that nanoparticles absorb thermal energy more effectively than surrounding fluid molecules, then transfer that energy through enhanced vibrational coupling.
This mechanism explains why even very small nanoparticle concentrations can produce measurable performance gains.
Producing nanoparticles with the right size distribution and stability is nontrivial. Khamlich compared two broad approaches: chemical and hydrothermal synthesis versus pulsed laser ablation in liquids. Chemical methods are well established but involve multiple processing steps, purification stages, and surfactants that can compromise stability and add cost. Particle size control is also challenging.
Pulsed laser ablation offers a cleaner alternative. A high-energy laser is focused onto a solid target submerged in a liquid, generating nanoparticles directly within the base fluid. The process produces particles below 10 nanometers with inherent electrostatic stability, eliminating the need for surfactants. It is a single-step method that yields clean, well-dispersed nanofluids.
While laser systems are capital-intensive, Khamlich argued that the economics shift at scale.
Chemical methods incur increasing costs as production volume rises due to processing complexity. Laser ablation, by contrast, scales more linearly and benefits from declining laser system costs worldwide.
As high-power laser platforms become more affordable, this approach becomes competitive for industrial nanofluid production.
The group demonstrated continuous-flow laser ablation systems capable of producing concentrated nanofluids that can later be diluted for use.
Copper nanoparticles synthesized directly in ethylene glycol and silicone oils showed tight size distributions below 10 nanometers, strong optical signatures, and minimal oxidation, with green laser wavelengths producing the narrowest spreads.
To quantify performance, the team built a guarded hot plate system rather than relying solely on commercial instruments, imposing a controlled heat flux between concentric cylinders to extract thermal conductivity across temperature ranges relevant to solar thermal operation.
The results pointed to practical relevance showing copper-based nanofluids delivered thermal conductivity gains of up to 30 percent at volume fractions as low as 0.002 percent, with smaller particles consistently outperforming larger ones and performance improving at higher temperatures.
Stability held across repeated thermal cycles, a prerequisite for industrial use. With testing now moving from the lab to operational collectors at their Green Energy Park, the focus has shifted toward deployment and manufacturing.
Khamlich framed the work as both an efficiency lever for Morocco’s solar investments and a potential export industry, arguing that nanofluids matter not as a breakthrough material, but as a way to remove a persistent bottleneck where heat transfer limits otherwise mature renewable systems.
For Morocco, and for other regions facing similar energy constraints, that path is less about inventing new systems than about making existing ones work harder, smarter, and longer.