Up-cycling plastic waste for distributed passive cooling applications

Project Information

CoolChips

Grant agreement ID: 101082087

DOI

10.3030/101082087

Project closed

EC signature date 15 June 2022

Start date 1 August 2022

End date 31 January 2024

Funded under

• European Research Council (ERC)

Total cost

No data

EU contribution

€ 150 000,00

Coordinated by

UNIVERSITAT BAYREUTH
Germany

Periodic Reporting for period 1 - CoolChips (Up-cycling plastic waste for distributed passive cooling applications)

Reporting period: 2022-08-01 to 2024-01-31

Summary of the context and overall objectives of the project

CoolChips addresses two grant challenges of our modern society: 1) Global warming requires new technologies to mitigate the ever-accelerating consequences of climate change. Passive daytime cooling is such an emerging technology that requires intricate photonic engineering of materials. 2) Plastic waste is evolving as an increasing challenge to keep our environment pollution-free. We, therefore, will investigate an up-cycling strategy to put used food-packaging polymers to an even better use in mitigating global warming. Consequently, we outline synthetic strategies to equip aluminium laminate polymer films, widely known for chips bags, etc., with an additional coating. This coating layer combination will be designed so that solar radiance will be fully reflected and thermal radiation in the mid-infrared range will be efficiently emitted. This unique combination of optical properties is the key to using cold outer space as a heat sink for our environment, day and night. We will achieve this goal by using our knowledge in polymer and composite materials synthesis and processing. We will further develop scalable processing strategies to glue or weld the individual recycling pieces to large passive cooling foils. This upcycling is vital for the envisioned transition to end-user products that can then be realized by established roll-to-roll processing technologies. Foreseeable application cases such as covers for tents, glue-able foils for blinds, or stand-alone parasols will be investigated with established industry partners. The development of the required processing steps and material selection will be tightly accompanied by an intellectual property patenting strategy and market analysis to ensure optimum exploitation of this promising novel material development. Overall, CoolChips will make passive daytime cooling materials accessible to various communities providing a green and affordable way to cooler environments.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The performed work focused on three parts: the technical development of suitable up-cycling coatings, the evaluation of exploitation strategies and the dissemination for reaching a broad and also non-scientific audience. During the development of the project we focused strongly on technical development, where we introduced different material combinations to achieve passive daytime coolings. With each step of development, the applied coating material comprises more easily available starting materials and the coating itself becomes more environmentally benign. Precisely, the first generation comprised polydimethylsiloxane, the second generation poly(ethylene terephthalate), the third generation polycaprolactone and the final generation starch as the polymer matrix. These first two coatings have already been published; the last two coating generations are ready for peer review. This development reflects our targeted goal of developing coatings that can be accessed by various communities in a green and affordable way.
For exploitation of our expected findings, we conducted a patent search at the beginning of the project. It became clear that several patents already claimed reflective polymer films with an emitting top coating. We, therefore, refrained from pursuing a patenting strategy based on the film composition. Strategies for exploiting such coatings, therefore, needed to target specific use cases and processing strategies that are not covered by the existing patents.
We actively disseminated our achieved results through open-access publications and further press releases. In particular, our press release on the first two generations of chips bag coatings was well picked up by local and national media, which resulted in two radio interviews (“Bayern1” and “BLR (Bavarian local radio stations)”), several online and printed articles, and a TV contribution (video shooting is still ongoing). Additionally, we developed simple experiments for educating pupils and the general public on the relevance of broadband optical engineering, radiative heat transfer, and passive cooling.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Overview of the results:
1) We successfully demonstrated that laminated Aluminium foils can be upcycled to functional passive daytime cooling materials. This provides an incentive for investigating further strategies to collect and isolate laminated aluminium foils from the waste stream.
2) We outline four different types of functional coatings that are suitable to achieve passive daytime cooling. While the polymer matrix of such coatings can comprise synthetic or biogenic base materials, the inclusion of porosity or a filler material improves the solar reflectance and, hence, the passive cooling performance.
3) Upcycled chip bags can be used to coat other objects, e.g. an umbrella, to improve thermal comfort.
4) We developed methods of sufficient simplicity and safety to be useable by the general public and without the necessity of sophisticated equipment or laboratory infrastructure.
Key needs for further uptake and success:
1) Scalability and long-term usage: While our results demonstrated passive cooling foils up to low sqm areas, further upscaling will be necessary. This entails major developments in collecting, cleaning, and processing chip bags. Considering weather conditions, a major necessity is the investigation of ageing processes on passive daytime cooling materials.
2) Value of cooling: The most important need is how to rate the value of cooling. Depending on the use cases, there will not be a simple way to determine the cost benefits of passive daytime cooling. In combination with established active cooling technologies, a cost reduction due to increased efficiency can be quantified. When it comes to thermal comfort due to reducing the urban heat island effect, a cost calculation becomes much less obvious. This is where a standardisation and regulatory framework will become essential, e.g. for future roofing, blinds, and shades, at least in urban constructions. This necessity needs to go hand-in-hand with standardisation efforts from the research community to still better quantify the cooling performance of the specific passive cooling materials.