Energy storage is the main challenge for a deep penetration of renewable energies into the grid to overcome their intrinsic variability. Thus, the commercial expansion of renewable energy, particularly wind and solar, at large scale depends crucially on the development of cheap, efficient and non-toxic energy storage systems enabling to supply more flexibility to the grid. The Ca-Looping (CaL) process, based upon the reversible carbonation/calcination of CaO, is one of the most promising technologies for thermochemical energy storage (TCES), which offers a high potential for the long-term storage of energy with relatively small storage volume. This manuscript explores the use of the CaL process to store Concentrated Solar Power (CSP). A CSP-CaL integration scheme is proposed mainly characterized by the use of a CO 2 closed loop for the CaL cycle and power production, which provides heat decoupled from the solar source and temperatures well above the ~550ºC limit that poses the use of molten salts currently used to store energy as sensible heat. The proposed CSP-CaL integration leads to high values of plant global efficiency (of around 45-46%) with a storage capacity that allows for long time gaps between load and discharge. Moreover, the use of environmentally benign, abundantly available and cheap raw materials such as natural limestone would mark a milestone on the road towards the industrial competitiveness of CSP.

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We have investigated the pattern of incorporation of 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU) by proliferating cells during regeneration of the tail fin of Carassius auratus. Fifteen days after amputation, intraperitoneal injection of a single dose of 0.25 mg/g wet weight of BrdU and subsequent immunocytochemical detection on sections revealed groups of replicating cells in the blastema and epidermis at different proximodistal levels. Proliferating blastemal cells were confined to a crowded, compact distal area that lost its replicative capacity laterally, causing the differentiation of scleroblasts, which synthesize the lepidotrichia hemisegments. Proximally, but centrally located, the blastemal cells did not incorporate BrdU and they differentiated giving rise to the mature intraray connective tissue. An independent cell-proliferation process was noted in the epidermis. The distal cap did not proliferate; the lateral faces of the epidermis showed high rates of cell replication in the central layer at every level of the regenerate rays; quiescent cells remained in the superficial layers. The basal epidermal cells did not incorporate BrdU when actinotrichia were present. The possible role of basal epidermal cells in the synthesis of actinotrichia, the contribution of these collagen macrofibrils to the morphogenetic process, and the different pathways of cell differentiation during fin regeneration are discussed.

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