Ikea sells its own balcony power plant for self-assembly.
From this week on, Ikea stores will offer a DIY balcony solar power kit for a small price. It comes with a portable battery included.
A research team from Singapore has developed a promising method to generate electricity from falling rain - and surprisingly efficiently.
The new technique is based on vertically standing, conductive-coated tubes through which rainwater flows intermittently. This so-called plug-flow generates significantly more electricity than a uniform water flow.
In the experimental setup, scientists used tubes with a height of 32 centimeters and an inner diameter of two millimeters. Inside, a special polymer ensures electrical conductivity. Raindrop-sized droplets are fed from above, forming short columns of water with air bubbles upon impact in the tube. This irregular, discontinuous movement causes the electrically charged particles in the water - positively charged H+ ions and negatively charged OH- ions - to separate more spatially. This creates a voltage that can be measured and utilized through electrodes on the tube.
Compared to previous experiments with continuous water flow, the new system achieves significantly higher efficiency. The researchers speak of a theoretical power density of around 100 watts per square meter - a value that is about five orders of magnitude above previous rain-based experiments.
The key to success lies in the flow behavior: the pulsating movement allows the ions to move further away from the surface of the tube than would be possible with a uniform water flow. This surpasses a previously considered physical limit distance, known as the Debye length. This discovery represents a breakthrough, as the low contact area of water with solid surfaces has been a limiting factor for energy generation from precipitation.
In practical terms, the potential of the method is evident: four of the tested tubes were able to provide enough power to permanently light a dozen LEDs. The tests also showed that the system can be easily scaled. Combining two tubes - side by side or end to end - doubles the amount of energy generated. However, the effect does not increase with tube lengths beyond 32 centimeters.
The new technology could be used in the future as a cost-effective and environmentally friendly supplement to conventional hydropower. Unlike large dams or turbine installations, the system requires neither large amounts of water nor complex infrastructure. Instead, it is particularly suitable for urban areas, such as rooftops or rain gutters, as well as remote areas without access to the power grid. The researchers see their development as a practical solution for decentralized power generation and a new way to utilize precipitation as a renewable energy source. The system is not only technically convincing but also easy to install and low maintenance - and could help advance the energy transition.