Solar Power Solar Power on Demand: Making Energy Available 24/7
Solar power in time could become a steady alternate power source replacing conventional methods of generating energy. Find out how Linde and its member companies are finding solutions to make this vision a reality.
These sun worshipers have no time for sunscreen. The silver sea of parabolic mirrors reaches up lazily towards the burning sun, catching as many rays as they possibly can. Every year, the sun beams 1.5 sextillion (1021) kilowatt-hours of sunshine down to the earth. The technologies already available today are capable of meeting 380 per cent of the world’s energy needs through solar power.
The parabolic mirrors are designed to automatically follow the sun in order to capture as much energy as possible. Shaped like a trough, the curved surfaces concentrate sunlight onto a receiver tube located at the focus of the parabolic mirrors.
“A heat transfer fluid flows through these receivers, absorbing the heat from the sun and transferring it from the solar field to the power plant. The energy stored in the medium can then be used to create power— as long as the sun stays shining at least,” explains Project Manager - Energy Production and Storage, Clean Energy and Innovation Management Unit, Linde, Stefan Hübner. As soon as the sun sets, radiation ceases and the solar power plant can no longer supply energy, unless it stored up excess energy during the day.
Making Solar Power Flexible
“With a storage solution, regenerative energy would also be available during the night,” adds Hübner. Working with his colleagues at Linde Group member Bertrams Heatec, Hübner is exploring ways to make solar power more flexible. One of the projects he is working on with DLR is called Direct Steam Generation Store (DSG Store).
This involves developing a totally new generation of thermal storage solutions for solar thermal power plants. Hübner clarifies, “We hope to gain valuable insights into the potential of this technology for other industrial applications. It could be used for instance to capture process off-heat.”
The heat transfer fluid plays a defining role in the efficiency of solar storage systems. In existing parabolic solar power plants, thermal oil typically flows through the receivers. It is heated to around 390°C as it passes through the solar field. In a second step, the thermal oil heats water, producing steam that drives a turbine to generate electricity. The downside of this oil is that it degrades at temperatures in excess of 400°C. Linde and DLR want to overcome this challenge by replacing oil with water as the direct working medium. Water could achieve higher temperatures and thus store more thermal energy.