Cooling is the fastest-growing use of energy but is also one of the most critical blind spots in today’s energy debate. Rising demand for cooling is putting enormous strain on electricity systems in many countries, as well as driving up emissions.
The European Commission’s Heating and Cooling Strategy identifies actions of ‘increasing the share of renewables’ and ‘reuse of energy waste from industry’ as two key areas for decarbonizing cooling to meet the EU’s climate goals by 2050. Therefore, the new technology development and adoption become critical to flexibly ‘absorb’ renewable energy and/or waste heat and then ‘convert into’ and also ‘store’ cooling energy to meet end users’ timely demand.
Researchers in the University of Birmingham’s School of Chemical Engineering and Birmingham Centre for Energy Storage are working on different novel cold storage and renewable refrigeration technologies to address the challenges. One example is the development of microencapsuled phase change materials (PCMs) for cryogenic-temperature cold storage and transportation.
Through the in-depth investigation and understanding of the in-situ polymerisation process, the researchers had successfully sealed the volatile PCM ‘heptane’, which is not effectively retained by common polymeric emulsifiers. The produced microcapsules have exceptionally large payload in terms of both volume (~97 vol%) and weight (~95 wt%), superb long-term retention capability at ambient conditions, as well as the surprising cryogenic-temperature survival during thermal cycles between 25 °C and -140 °C.
The project was funded by EPSRC and the research results were published in Chemical Engineering Journal. Professor Yongliang Li, the principal investigator of the project, says: ‘the potential value of cryogenic-temperature cold storage has been widely recognised for the much-elevated exergy density and the capability of cogeneration of cold and power.
The related UK leading technologies those under development including cryogenic engine for transportation, liquid air energy storage, pumped thermal electricity storage etc., in which cryogenic temperature cold storage is a key to improve the performance’.
The work addressed the key challenge for the development and application of cryogenic slurry, which is a suspension of the PCM microcapsules into a carry fluid. The cryogenic slurries are excellent cold storage candidates as they can be transported by pumps (good fluidity), and their effective temperature-dependent heat capacity can be designed easily by adding different capsules with appreciate freezing point core PCMs to minimize the exergy loss in charging/discharging processes.
The research activities in the School of Chemical Engineering on sustainable cooling has been further explored with recently awarded sizeable Governmental funding. Backed by £1.4 million of UKRI funding, the four-year Zero Emission Cold-Chain (ZECC) project led by
Professor Toby Peters will create the first detailed road map to allow the UK food cold chain industry to identify opportunities to reduce emissions. In parallel, the £1.5 million Heat Accumulation from Renewables with Valid Energy Storage and Transformation (HARVEST) project led by Professor Yongliang Li will develop new heat/cold storage and conversion technology to help ensure that renewable electricity is stored in times of less electricity demand and ready for use to meet high heating demand in winter and high cooling demand in summer.
More details can be found via our article on future sustainable routes and technologies.
In addition, researchers in the School of Chemical Engineering are also leading on a green cooling technologies programme consisting of 12 research institutions and 5 industrial companies all over the world to accelerate new cooling technologies into the marketplace.
Such a four-year project named CO-COOL, is funded by the EU Horizon 2020 under its Marie Sklodowska-Curie Research and Innovation Staff Exchange programme. You can find out more through our article detailing the programme.