One of the barrier to the use of renewable energy (solar and wind) is their intermittency. As more renewable sources of energy comes online, it become more difficult to balance between production and consumption. In Inner Mongolia, wind farm operators have to turn off ("abandon the wind") their turbines during winter nights because of the lack of demand during those times, having to discard 36 GWh of electricity every night. Storage will also reduce the necessity to have excess underutilized generation capacity to handle peak loads. Renewable sources of energy are usually located far away from where there are needed. The current peak/off peak prices of electricity is an artifact of the limitations of existing technology.
This concept is similar to a flywheel, but it solves its main weakness by eliminating the hub. This kinetic energy system stores energy in magnetically levitated slugs maintained at high speed inside a loop of evacuated tube. In the constant mass version, energy is injected by increasing the speed of the slugs and energy is extracted by decreasing the speed of the slugs, energy can be injected and extracted at any point in the tube. This version can also serve as a power transmission network. In the constant speed version, energy is injected by adding slugs and extracted by removing slugs at a central station. Both versions can also be used to transport freight that can withstand high G forces. The elimination of air drag and rolling resistance allows most of the energy spent during acceleration to be recovered when decelerating. Energy may actually be gained when going from high elevation to low elevation.
The capital cost $/kW/km is inversely proportional to the square root of the kW or kWh of energy storage required. This system is suitable for energy and power applications that requires more than 5 GWh of storage. This system have much bigger MW carrying capacity than overhead lines and cheaper than underground lines.
In conjunction with electrification of transport, this technology will allow most the energy requirements of transport, energy and heating to be sourced from renewables.
Calculates the cost and performance of the system given the Energy storage capacity required. Use Google Chrome if the graph does not appear.
Evacuated Tube Transport
United States Patent No. 5,950,543 Evacuated Tube Transport
Prospects for Large-Scale Energy Storage in Decarbonised Power Grids
Energy efficient, environmental friendly, cost effective, convenient, safe and fast transportation system for passenger and freight traffic
The Role of Energy Storage in Helping Global Energy Problems Become Gone With The Wind
Electricity Energy Storage Technology Options
Last updated: 20 October 2012