Airbags: For Environmental Safety Too
It is unlikely that insurance providers will offer discounts but offshore wind could soon be installing airbags. Hydrostor, hailing from Toronto, Ontario, has developed an energy storage system for offshore wind using compressed air. Air stored in bags under the sea could be used as a “battery”.
One of the hurdles for renewable energy sources is to provide energy on demand. Solar energy does not produce in the dark and wind energy, well, needs wind. While it is possible to store energy for when it is needed, the process takes energy, reducing overall efficiency. In essence, batteries are needed but battery technology is not efficient enough to be cost effective.
Hydro power is capable of producing on demand and can be brought on line more rapidly than fuel burning generators. The ability to store energy, as water, in a reservoir, a “battery”, means it is available anytime. The global water cycle, which is powered by solar energy, is the pump that refills the reservoirs. Without the water cycle it would be necessary to directly apply energy to move the water back into the reservoir.
When the wind turns a turbine, simply, electricity is produced. When the production is greater than the demand, the Hydrostor system will use the electricity to power a compressor. The compressor fills airbags about the size of a bus, approximately 50 cubic meters, anchored to the bottom of the ocean or lake.
When demand is greater than production, the airbags can be tapped to turn a generator and produce electricity. Installing the bags below a specific depth guarantees the minimum pressure available. The water pressure maintains sufficient air pressure to turn the generator even as the volume of air inside the bag is reduced.
Offshore wind solves some of the issues affecting onshore wind. Noise concerns and aesthetic considerations are removed once the installation occurs offshore and over the horizon. Maintenance can be performed more easily on dry land and grid tie-in is typically a simpler process for onshore wind. Offshore wind requires a high voltage transmission cable to be run underwater to the offshore wind farm.
True battery storage of electricity is not efficient but renewables are finding natural “batteries”. Hydro power stores energy as water and Hydrostor provides the means for wind power to store energy as wind, with an assist from water. To prove they aren’t just tilting at windmills, Hydrostor intends to install 225 bags as part of a future offshore wind farm in Lake Ontario. The wind farm itself is going through the approval process currently.
Photo Credit: Kim Hansen