Scientists may have uncovered the solution to the problem of long-term energy storage by developing a device that uses a specialized fluid that can store solar power for more than 10 years. The renewable, carbon-free energy device is made up of a concave reflector with a pipe in the center, which tracks the Sun like a satellite dish. With tests showing signs of success, the device is attracting the attention of investors. If all goes well, the technology is expected to be available for commercial use within 10 years.