Energy is inevitably trending towards local energy production and management. However, a significant barrier is the inability to effectively, efficiently and cheaply store this locally produced energy. Until now, the main storage option was pumped storage power plants (Poland). Another method is compressed air storage, which receives off-peak electricity. This is used to compress and store fuel which is used later to drive the gas turbine during the peak season.
The German Fraunhofer Institute (Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V.), which is one of the most innovative and important scientific organizations supporting industry in Europe, has been experimenting with storing energy in the sea (Stense Stored Energy in Sea). Concrete balls with built-in turbines are to be filled with water and placed on the bottom of the Mediterranean Sea and the Atlantic Ocean (in the ideal version - at a depth of 600-800 meters). Electricity would be used to pump water out of the sphere into the sea. In order to produce it, the pump would work in the opposite direction and the water would flow into the concrete space. Plans are for warehouses with a capacity of 5 MWh and 20 MWh3.
Due to their high degree of flexibility, the most potential lies with fuel cells (suing hydrogen) and lithium batteries, due to their constantly increasing capacity and the ability to ensure the stabilization of the electricity network in the future. Elon Musk has followed this path and, in 2016, Tesla began to offer small scale energy storage with the so-called Powerwall in two capacities - 7 kWh and 10 kWh. Quite quickly, a second option dedicated to companies was abandoned. Parallel sales of Powerwall, with a capacity of 6.4 kWh for households that need to store energy from their own photovoltaic installation, was planned in anticipation of demand.
Recently, Elon Musk unexpectedly presented Powerwall 2 with a nominal capacity of 14 kWh (really 13.5 kWh) and power 7 kW at peak and 5 kW in continuous mode. It is slightly heavier than its predecessor - approx. 120 kg, but smaller (115 cm × 75.5 cm × 15.5 cm) and more efficient. The warranty covers an unlimited number of charging cycles over a period of up to 10 years. The device costs $5,500, that is, for one unit of capacity, you have to pay 2.46 Wh / USD.
Powerwall 2 is a pre-installed inverter whose task is converting direct current to alternating current. The direct current generated in the photovoltaic cells is not suitable for powering home appliances - it has to be converted in the inverter to a nominal voltage of 230 V and 50 Hz. The functionality of the new Powerwal brings us significantly closer to the vision of energy self-sufficient housing estates and communes. Energy storage has been one of the topics most frequently discussed topics in recent years.
By PowerUp! Team on in PowerUp! 2018