Sorption heat storage for long-term low-temperature applications: A review on the advancements at material and prototype scale

Sorption heat storage has the potential to store large amounts of thermal energy from renewables and other distributed energy sources. This article provides an overview on the recent advancements on long-term sorption heat storage at material- and prototype- scales. The focus is on applications requiring heat within a temperature range of 30–150 °C such as space heating, domestic hot water production, and some industrial processes. At material level, emphasis is put on solid/gas reactions with water as sorbate. In particular, salt hydrates, adsorbents, and recent advancements on composite materials are reviewed. Most of the investigated salt hydrates comply with requirements such as safety and availability at low cost. However, hydrothermal stability issues such as deliquescence and decomposition at certain operating conditions make their utilization in a pure form challenging. Adsorbents are more hydrothermally stable but have lower energy densities and higher prices. Composite materials are investigated to reduce hydrothermal instabilities while achieving acceptable energy densities and material costs. At prototype-scale, the article provides an updated review on system prototypes based on the reviewed materials. Both open and closed system layouts are addressed, together with the main design issues such as heat and mass transfer in the reactors and materials corrosion resistance. Especially for open systems, the focus is on pure adsorbents rather than salt hydrates as active materials due to their better stability. However, high material costs and desorption temperatures, coupled with lower energy densities at typical system operating conditions, decrease their commercial attractiveness. Among the main conclusions, the implementation within the scientific community of common key performance indicators is suggested together with the inclusion of economic aspects already at material-scale investigations.This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. TU/e has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). The results of this study can contribute to the development of educational material within INPATH-TES

Energy density and storage capacity cost comparison of conceptual solid and liquid sorption seasonal heat storage systems for low-temperature space heating

Sorption heat storage can potentially store thermal energy for long time periods with a higher energy density compared to conventional storage technologies. A performance comparison in terms of energy density and storage capacity costs of different sorption system concepts used for seasonal heat storage is carried out. The reference scenario for the analysis consisted of satisfying the yearly heating demand of a passive house. Three salt hydrates (MgCl2, Na2S, and SrBr2), one adsorbent (zeolite 13X) and one ideal composite based on CaCl2, are used as active materials in solid sorption systems. One liquid sorption system based on NaOH is also considered in this analysis. The focus is on open solid sorption systems, which are compared with closed sorption systems and with the liquid sorption system. The main results show that, for the assumed reactor layouts, the closed solid sorption systems are generally more expensive compared to open systems. The use of the ideal composite represented a good compromise between energy density and storage capacity costs, assuming a sufficient hydrothermal stability. The ideal liquid system resulted more affordable in terms of reactor and active material costs but less compact compared to the systems based on the pure adsorbent and certain salt hydrates. Among the main conclusions, this analysis shows that the costs for the investigated ideal systems based on sorption reactions, even considering only the active material and the reactor material costs, are relatively high compared to the acceptable storage capacity costs defined for different users. However, acceptable storage capacity costs reflect the present market condition, and they can sensibly increase or decrease in a relatively short period due to for e.g. the variation of fossil fuels prices. Therefore, in the upcoming future, systems like the ones investigated in this work can become more competitive in the energy sector.This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. TU/e has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement Nº 657466 (INPATH-TES). The results of this study can contribute to the development of educational material within INPATH-TES

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

An estimation of the European industrial heat pump market potential

This paper presents an estimation of the European (EU28) industrial heat pump market potential in terms of magnitude, sizing and number of units. This study is carried out in order to provide technology suppliers and manufacturers of industrial heat pumps perspectives for the technology. Potential heat pump applications in the food, paper, chemical and refining sectors are identified considering a maximum sink temperature of 200°C. This is achieved utilising a bottom-up methodology that uses detailed information from individual processes in the aforementioned sectors. Combining individual process data with typical plant capacities provides information on the heating capacities of heat pumps. The data is upscaled to European level, using production statistics relevant to the individual processes analysed. Since the database of processes is generic in nature and not fully covering the whole industrial sector, the results of this analysis provide a conservative estimate of the heat pump market potential. The results show a potential cumulative heating capacity of industrial heat pumps in EU28 of 23.0 GW, consisting of 4174 heat pump units which are able to cover 641 PJ/a of process heat demand. The largest number of heat pump units (%) can be found for heating capacities <10 MW, making up about 50% of the total market cumulative heating capacity. Clearly, there is a large market ahead for industrial heat pump manufacturers and suppliers

Seasonal sorption heat storage - research on thermochemical materials and storage performances

Advantages of thermochemical heat storage over conventional heat storage are a higher energy density and loss-free storage of the heat after charging, since the heat is stored in chemical form. At ECN, a thermochemical heat storage is developed for seasonal heat storage applications. This paper shows results of materials testing, experiments with a lab scale reactor and first modeling results. The required output temperature of 60°C was realise

Thermochemical storage for long‐term low‐temperature applications: Performance estimation of ideal systems

Thermochemical heat storage has the potential to store a large amount of thermal energy from renewables and to cope with the seasonal mismatch of energy demand and supply, ideally without energy losses typical of sensible heat storage. However, in order to have a commercially attractive system, research at material, reactor, and ultimately at system level is still required. The aim of this work is to investigate the current state-of-the-art research at prototype- and system-scale, and to estimate the performance of ideal long-term low-temperature thermochemical storage systems in terms of energy densities and storage capacity costs. First, a review on existing systems based on solid/gas reactions is carried out. Especially for open systems, the choice of adsorbents rather than salt hydrates as active materials is prominent due to their enhanced stability. However, high material costs and desorption temperatures, coupled with lower energy densities, decrease their commercial attractiveness. Then, the performance of ideal open thermochemical heat storage systems based on solid/gas reactions are estimated for different active materials among which salt hydrates, an adsorbent, and an ideal composite. The common reference scenario assumes that the seasonal space heating energy of a passive house has to be stored. The results show that the open system based on a composite material, can represent a valid compromise between hydrothermal stability and storage capacity costs. However, it results in a very large system for the assumed reference scenario conditions. The performances of open systems are then compared with the ideal performance of closed solid sorption systems. The results show that closed systems are in general more expensive and less compact for the assumed reactor layouts. Finally, liquid sorption systems from the literature are compared with the open and closed solid sorption systems. The results show that most of the liquid systems are not able to achieve the minimum temperature required by the consumer in the reference scenario. However, a liquid sorption system based on NaOH-H2O can in principle satisfy the consumer needs and result more compact and less expensive than solid sorption systems based on pure adsorbents and certain salt hydrates. Beside research at material- and reactor-scale, integration of thermochemical storage at grid level has to be investigated to assess its techno-economic feasibility based on their performance and interactions with production and consumption technologies

Proteoglycans in health and disease: novel regulatory signaling mechanisms evoked by the small leucine-rich proteoglycans.

The small leucine-rich proteoglycans (SLRPs) are involved in many aspects of mammalian biology, both in health and disease. They are now being recognized as key signaling molecules with an expanding repertoire of molecular interactions affecting not only growth factors, but also various receptors involved in controlling cell growth, morphogenesis and immunity. The complexity of SLRP signaling and the multitude of affected signaling pathways can be reconciled with a hierarchical affinity-based interaction of various SLRPs in a cell- and tissue-specific context. Here, we review this interacting network, describe new relationships of the SLRPs with tyrosine kinase and Toll-like receptors and critically assess their roles in cancer and innate immunity

Techno-economic optimization of an energy system with sorption thermal energy storage in different energy markets

Sorption thermal energy storage (STES) has the potential to have higher energy densities and lower thermal losses compared to conventional thermal storage technologies, and it can contribute to increase the energy grid flexibility and the penetration of intermittent and distributed energy sources. However, STES is a technology still under research, and system-scale investigations are necessary to determine its potential in future energy systems. In this regard, the objective of this work is to investigate the STES potential in a reference energy system interacting with different energy markets. The system consists of a geothermal doublet supplying thermal energy to an organic Rankine cycle (ORC) and to a district heating network that satisfies the thermal energy demand of a residential neighborhood. A techno-economic optimization of the energy system is carried out using mixed integer linear programming. The optimization aims at finding the optimal STES size and system operational behavior that maximizes the yearly profits from selling the ORC energy to the energy markets. Among the main results, it is found that the STES integration increased the overall system profits by 41% in the scenario where the ORC interacted with the UK day ahead market (2017 data), and with two UK balancing services: the capacity market, and the short term operating reserve. In conclusion, this work highlights how a thermal storage technology still under research could become an asset under specific market conditions. Future policy mechanisms can benefit from similar analyses and foster the integration of new technologies into the energy grid