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

需要。到2030年，发展中国家三分之一的人口将居住在水需求和供水之间的差距预计超过50%的地区。通过利用传统工程技术开发替代水资源来弥补这一短缺，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，干旱造成的经济损失估计为290亿美元。愿景：该项目将开发一种生物泵，能够被动地将地下水从数十米至数百米的深度提升，仅使用大气自然提供的能量。这种仿生系统使用岩土工程中的新兴材料和概念来模仿植物用于蒸腾的毛细作用机制。通过将胶体二氧化硅基水凝胶注入土壤和岩石中，将产生土壤-水凝胶网络，其在高负土壤水压力期间（即当土壤非常干燥时）具有增加的土壤水力传导性和保水能力。该网络的设计目的是在干旱期间将深层地下水位的水被动提升到近地表土壤。植物和树木。树木中的水压已被证明达到低至-10MPa的值，这在理论上相当于1公里的毛细上升。在这样的系统中，由于毛细管纳米多孔界面的存在，可以保持高的水张力，该界面防止空气进入，从而抑制空气播种和空化（气泡）。在土壤-植物连续体的不同部分发现了纳米孔界面。在叶子中，这样的纳米孔维持负木质部水压和周围大气气压之间的差异。在茎中，纳米多孔网络分割木质部血管，为树木提供隔离扩大的空气腔和防止扩散栓塞的能力。水凝胶挑战：目的是通过注入纳米多孔水凝胶来改变土壤/岩石孔隙网络，以创建植物根系的“水力延伸”。水凝胶形成为一种或多种交联的纳米颗粒聚合物的网络。它们的特点是高亲水性，其性能只是最近才被调查的岩土工程应用。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，它们也可以促进水通过其孔隙转移。该项目将解决三个不同的挑战，每一个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，可注入土壤;在灌浆土壤中创建一个连续，持久的纳米孔网络，可以抵抗反复的湿润和干燥循环;证明植物在连接到“无能源水泵”时可以茁壮成长。

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".