What’s popping up in my news feeds thanks to the Climate Change conference is incredibly interesting! Here’s a new energy storage system now being tested off Lake Ontario. Makes sense given all those wind turbines we saw travelling through the Windsor area last summer!
Essentially, renewable energy sources run a compressor that pumps air into the system through one pipe. A turbine is powered by compressed air coming from another pipe providing constant AC power. An inter-cooler system harvests cold air exiting at the turbine to cool pressurized air entering from the compressor. This would negate thermal loss.
What’s interesting about this technique is the fact that Boyle’s law dictates that the pressure output will be constant regardless of the actual volume of air in the balloons. This is a real game changer!
There are a number of permutations on this design that would make it feasible for many different applications. Consider the simple construction of an underground vertical bore whose top sits below the deepest portion of a nearby pond/lake. In this bore rides an airtight piston. Water from a nearby pond is piped to the upper portion of the bore, above the piston, while compressed air is stored in the lower portion under the piston.
When pressurized air from the compressor side of the system is pumped in, the piston rises higher in the bore. Conversely, when this same pressurized air is siphoned off to drive the turbine, the piston in the bore lowers. Net pressure on piston seals is zero so the design can leverage existing and inexpensive technology.
A different (and even easier) way to do this would be to simply cap the bore at the top with the compressor/turbine pipes. Water from the lake would enter from below and initially fill the entire bore. Pressurized air delivered by the compressor would lower the water level in the bore, while pressurized air used by the turbine would raise it. In this design, some sort of safety system would have to be developed to prevent water from entering the turbine tube if demand outstripped the system’s storage capacity.
I’m currently doing some feasibility calculations on this design. How big must the system be to power a house? How big for a microgrid? How does available water depth impact system sizing?