In much of Canada, the electric utilities have Hydro in their names, like Hydro One or Quebec Hydro, because their electricity was generated hydro-electrically from Niagara Falls or big dams. The nice thing about hydro-electricity is that it pretty much always runs; the problem with renewables like wind and solar is that they don't, and storage becomes a big problem. Lots of ideas are being tried, from batteries to flywheels, but deep in the water off the Toronto Islands, one company is using the pressure of good old Hydro. We described Hydrostor back in 2011 as How To Store Wind Power: Pump It Into A Big Underwater Balloon, when they were prototyping it in a swimming pool but now Hydrostor has a full-sized working system. From the press release:
The Hydrostor system will be operated by utility host Toronto Hydro and is designed to store electricity during off-peak hours when demand is low and electricity is cheapest, and return the stored electricity during times of high demand or during short-term power outages.
It's so simple conceptually: they run a compressor, housed in that totally boring building (why can't people hire architects for such important projects?) that pumps air 2.5 km (1.5 miles) offshore into giant air bags, the kind that have been used for years to lift shipwrecks off the sea floor. Compressing air generates a lot of heat, which is stored as well., Curtis VanWalleghem, CEO of Hydrostor, explains in the National Post:
“The heat sits right beside the building in an insulated thermal reservoir, anything from packed concrete rocks to pressurized water to graphite rocks.”
When power is needed, the process is essentially reversed. The video is fascinating, showing how the bags are actually installed.
“When the valve is opened, the weight of the water all around that air cavity forces the air to come up to the lower pressure,” Mr. VanWalleghem said. The air is reheated and begins turning a low-pressure turbine, reproducing power.
It's a terrific idea, and would be even better if the NIMBYs hadn't killed offshore wind in Lake Ontario nearby. This could have stored much of the power and the NIMBYs wouldn't even know they were there unless they dropped an anchor off their yachts.
Hydrostor has cracked the toughest nut of cleantech - low-cost grid-scale energy storage” enthused Tom Rand, Managing Partner of ArcTern Ventures – and early backer of Hydrostor. "By enabling a flexible and robust grid, energy storage enables massive penetration of renewables at increasingly competitive pricing."
Next up, according to Fast Company, is a project In Aruba. According to VanWallegham, " "The economics get better the deeper you go," he says. "The ideal site is 200 meters [deep] within about [2.4 miles] of shore."
In Toronto the windbags are usually found at City Hall; putting them deep under water a mile offshore is a much better idea. More at Hydrostor.