An energy free pump: nanoporous gels to passively lift subsurface water

的需要。到2030年，发展中国家三分之一的人口将居住在用水需求和供水缺口预计将超过50%的地区。利用传统工程技术开发替代水资源来满足这一短缺将耗尽宝贵的能源资源，并产生巨大的成本。在全球范围内，2010年至2015年期间，与干旱有关的经济损失给农业造成的损失估计为290亿美元。愿景：该项目将开发一种生物启发泵，能够被动地从几十米到几百米深处抽取地下水，只使用大气自然提供的能量。这个受生物启发的系统使用了岩土工程中的新兴材料和概念来模仿植物用于蒸腾的排汗机制。通过将胶体硅基水凝胶注入土壤和岩石中，将形成一个土壤-水凝胶网络，该网络在高负土壤水压期间（即土壤非常干燥时）具有更高的土壤水力导电性和保水能力。该网络将被设计成能够在干旱期间从深层地下水位被动地提升到近地表土壤。植物和树木。树木中的水压可低至-10MPa，理论上相当于毛细管上升1公里。在这种系统中，由于存在毛细管纳米孔界面，可以防止空气进入，从而抑制空气播种和空化（气泡），因此可以保持高水张力。纳米孔界面存在于土壤-植物连续体的不同部分。在叶片中，这些纳米孔维持着木质部负水压和周围大气气压之间的差值。在茎中，纳米孔网络分割木质部血管，为树木提供隔离膨胀的气腔和防止弥漫性栓塞的能力。纳米孔土壤-根界面也可以防止空气的进入。水凝胶挑战：目标是通过注入纳米多孔水凝胶来改变土壤/岩石孔隙网络，从而创建植物根系的“水力延伸”。水凝胶形成一个或多个交联的纳米颗粒聚合物的网络。它们的特点是高亲水性，它们的性质直到最近才被研究用于岩土工程应用。申请人在准备本次投标时进行的初步实验表明，即使在孔隙水压力为-10 MPa的情况下，它们也能促进水通过孔隙的转移。该项目将解决三个不同的挑战，每个挑战都对系统的成功至关重要：设计一种具有合适水力特性的水凝胶，可以注射到土壤中；在灌浆土壤中创建一个连续的、持久的纳米孔网络，可以抵抗反复的干湿循环；以证明植物可以在连接到“无能源水泵”时茁壮成长。

THE NEED. By 2030, a third of the population in developing countries will reside in areas where the gap between water demand and water supply is predicted to be over 50%. Meeting this shortfall by exploiting alternative water resources using traditional engineering technologies will deplete valuable energy resources and incur significant cost. Globally, drought-related economic losses between 2010 and 2015 had an estimated cost to agriculture of $29 billion.THE VISION: This project will develop a bioinspired pump capable of passively lifting subsurface water, from depths of tens-to-hundreds of meters, using only energy that is provided naturally by the atmosphere. This bioinspired system uses emerging materials and concepts in geotechnical engineering to mimic the wicking mechanisms plants use for transpiration. Through the injection of a colloidal silica-based hydrogel into soils and rocks, a soil-hydrogel network will be created that has an increased soil hydraulic conductivity and water retention capacity during periods of high negative soil water pressure (i.e. when the soil is very dry). The network will be designed to enable the passive lifting of water from a deep groundwater table to near-surface soils during periods of drought. PLANTS AND TREES. Water pressure in trees has been shown to reach values as low as -10MPa, which is theoretically equivalent to a capillary rise of 1 km. In such systems, high water tension can be maintained thanks to the presence of a capillary nanoporous interface that prevents the ingress of air thus inhibiting air seeding and cavitation (air bubbles). Nanoporous interfaces are found in different parts of the soil-plant continuum. In the leaves, such nanopores maintain the differential between the negative xylem water pressure and the surrounding atmospheric air pressure. In the stem, nanoporous networks segment xylem vessels, providing the trees with the capacity to isolate expanding air cavities and prevent diffuse embolism. Nanoporous soil-root interfaces also prevent the ingress of air.THE HYDROGEL CHALLENGE: The aim is to modify a soil/rock pore network via injection of nanoporous hydrogel to create a 'hydraulic extension' of a plant root system. Hydrogels are formed as a network of one or more cross-linked nanoparticulate polymers. They are characterised by high hydrophilicity and their properties are only recently being investigated for geotechnical applications. Preliminary experiments by the applicant, in preparation for this bid, have shown they can facilitate water transfer through their pores even at porewater pressures of -10 MPa. The project will tackle three different challenges, each vital to success of the system: to design a hydrogel with suitable hydraulic properties, that is injectable into the soil; to create a continuous, durable network of nanopores within the grouted soil that is resistant to repeated cycles of wetting and drying; to demonstrate that plants can thrive when connected to the "Energy-free water pump".