How Does Gravity Storage Work? There are several different gravity-based storage systems. Let's take a look at two different types. New Energy Let's Go UG (a privately held company) is based in Hamburg, Germany. Its system is based on the hydraulic principles of fluids, and it's currently in the conceptual stages. It involves lifting a very large, cement-covered rock mass (pictured in white below). Think of it as a giant piston inside a huge cylinder. The piston has a gasket that creates a tight seal between it and the cylinder wall. This prevents water from escaping between the cylinder and the piston. The only way water can get under the piston is through a pipe connected to the bottom of the cylinder. The mass is raised using giant pumps. They pump water out of a holding pond on the surface. The piston is slowly raised by hydraulic pressure. This happens mainly during the day. That's when renewable energy sources produce excess power. Once the piston is raised, valves close to keep it in place. At night - or whenever peak power is needed - the valves open. Gravity makes the piston slowly descend. The water, under tremendous pressure, flows through turbines connected to generators. The amount of storage a system like this is capable of providing involves complex calculations. But it's essentially determined by the diameter and depth of the cylinder and the size and weight of the rock mass. Another form of gravity-based energy storage is under development by London-based Gravitricity (another privately held company). Its patented technology is simple. It starts with a vertical shaft that can be anywhere from 150 meters to 1,500 meters deep. During times of excess renewable energy production, its four motors raise a weight of up to 5,000 metric tons to the top of the shaft. During times of peak demand, the motors electronically transform into generators that spin as the weight lowers to the bottom of the shaft. Gravitricity claims its system can store energy at 50% of the cost of a lithium-ion battery storage system. Its systems have a design life of 50 years. The company has demonstrated a prototype system already as a proof of concept. This year, it plans to develop a full-scale project at a mine site in the Czech Republic. When it's operational, it could deliver 4 to 8 megawatts of storage. The company estimates there are about 14,000 abandoned mine sites around the world that would be suitable for this type of energy storage. It's clear that gravity-based systems will play a significant role in the future of energy storage. I will continue to investigate and report on these developments. Good investing, Dave P.S. Gravity-based energy storage will be huge, but it's nothing compared with the trends that are taking the clean energy sector by storm right now. To read about my top five renewable energy trends to watch in 2022, click here. | 
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