Welcome to the Glass Age

64 agriculture, animal husbandry and other fields. As science and technology advanced, solar thermal utilization has expanded from low temperature applications (<100ºC) to medium and high temperature applications ( ≥ 100ºC). New technologies such as solar thermal power generation (Figure 4.4), solar stills for water purification and distillation, integrated solar buildings and thermochemical hydrogen production have been developed in recent decades to provide clean energies of higher-grade. The key technologies for solar thermal utilization are heat collection, transmission and storage, and new glasses play a critical role in all three. In heat collection, the core component is the concentrating reflector, composed mainly of ultra-clear glass (also known as low-iron glass). The concentrating reflector is normally composed of a 1 mm to 4 mm ultra-clear glass substrate coated with a reflective silver layer, protected with a layer of copper and several protective paints on the back. For a concentrating reflector, reflectance can increase by 1.5% for every 1% increase in glass transmittance. Thanks to continuous optimization of raw material formulation and furnace structural design as well as fine control of the melting process, ultra-thin and ultra-clean glass with high transmittance and high weather resistance can be produced, paving the way for high- quality heat collection and highly efficient thermoelectric conversion. Additionally, in heat transmission, the inner metal tube coated with a medium-high temperature selective absorption coating is sealed in a borosilicate glass tube with good acid and water resistance and a well-matched coefficient of linear expansion to the metal phase, bringing in a medium-high temperature solar vacuum tube collector with an operating temperature up to 400°C —a temperature that ensures more stable and efficient transfer and utilization of solar heat. In heat storage, by adding transparent phase-change materials to the glass envelope, the newly developed glass curtain wall can utilize solar energy effectively and reduce energy consumption of buildings. It is critical to the development of ecological architecture and the realization of a carbon neutral strategy. Therefore, new glass materials remain the basic component to enable efficient utilization of solar heat. Highly efficient use of solar heat is an important aspect of solar energy utilization. Thanks to continuing R&D efforts, new glass materials are increasingly used in solar heat. Undoubtedly, the development of these new materials and technologies will bring new opportunities and challenges to the solar thermal industry, nurturing economy of scale, accelerating commercialization, and promoting Figure 4.5. Wind Farm. Source: Pixabay.