HARRISTON, ONT. - The trouble with electricity is that no one’s figured out how to bottle it when there’s too much, and uncork it later when there’s too little.
An unassuming industrial building 160 kilometres northwest of Toronto houses an operation that’s trying to store juice — not in bottles, but by using rapidly spinning, four-tonne steel cylinders.
It’s the brainchild of Annette Verschuren, chief executive of NRStor Inc. — which owns the operation — and Cam Carver, chief executive of Temporal Power Ltd. — which supplied the technology.
Storing electrical energy is an increasing challenge, especially as Ontario and other jurisdictions turn to sources such as wind and solar power that vary with the weather.
The province’s long-term energy plan is seeking 50 megawatts of energy storage capacity.
Toronto-based NRStor and Mississauga-based Temporal are testing flywheel technology for this trial: Using energy from the power grid to set the cylinders spinning, then using the momentum stored in the spinning cylinders to generate power and return it to the grid when needed.
It is, say Carver and Verschuren, the first grid-connected operation of its type in Canada.
Carver, the proud technology papa, adds: “It stores more energy than any flywheel in the world.”
The heart of the facility lies in vaults beneath 10 massive, round concrete caps that line the floor.
Entombed beneath the 10 caps are assemblies each housing a steel cylinder that weighs four tonnes and stands 2.5 metres high.
At the base of each cylinder is an electric motor, hooked up to the power system. The motors can set the cylinders spinning at up to 11,500 revolutions per minute.
When the power grid needs energy, the momentum of the spinning cylinders is used to drive the motors in reverse, turning them into generators that feed electricity back out into the grid.
The station receives a signal from the electricity system controller every four seconds telling it to feed energy into the grid, or draw it out. And it can jump from drawing energy in to out — or vice versa — in a quarter of a second.
That agility is one of its strengths.
The purpose of the Harriston facility is not to pump massive amounts of electricity system into the grid: It generates a maximum of two megawatts. (Ontario can suck up 25,000 megawatts on a hot summer day.)
It’s there to help manage the second-by-second fluctuations on the system as electrical machines and appliances are switched on and off — and as generators come on and off the system to meet the ever-varying load.
Currently, the system has to pay some generating stations to stay on standby, feeding varying amounts of energy into the grid to keep the system stable.
The theory is that flywheels can provide that service more efficiently than having generators on standby.
“We believe this type of technology will get costs down,” says Verschuren. It will free up existing generators to pump energy into the grid, while facilities like NRStor’s keep the grid stable.
That’s the theory. Does it work in practice?
The Harriston facility has been built to find out, so that both the company and the Independent Electricity System Operator (IESO) can figure out how it works in real life.
NRStor has a three-year contract with the IESO to give it a try. Neither Verschuren nor Carver would talk money — how much the facility cost, nor how much it gets paid for the service it’s providing.
The facility, and the flywheel technology, will have to compete against other forms of energy storage that are also under consideration.
NRStor itself is looking at more than one form of storage.
Verschuren wants to try pumping compressed air into underground salt caverns, using the stored energy to drive generators when demand is high.
Other companies are using electricity to make hydrogen, which can then be stored and used to power fuel cells.
On a bigger scale — 174 megawatts — Ontario Power Generation has been storing power for many years at the Sir Adam Beck Generating Station in Niagara, pumping water uphill into a reservoir at night so it can run through the hydro station and produce electricity during the day.
Verschuren has her eye firmly on larger-scale projects once the three-year Harriston trial is done.
“I would love to see up to 100 megawatts of this type of energy storage in Ontario,” she said. “But I think the next logical step is 20 megawatts, after this two-megawatt project.”