A recent deal to build a proposed transmission line that crosses the international border with Canada has the potential to enable the storage of abundant wind power from the US in a giant hydro “battery” in Manitoba.
A pair of utilities, Minnesota Power and Manitoba Hydro, have inked a Renewable Optimisation Agreement (ROA) under which electricity from excess wind produced in North Dakota can be stored in Manitoba’s hydro reservoir when loads and prices are low, with the potential for selling that power back onto the huge United States Midwest Independent Transmission System Operator (MISO) market at times when needs are high.
The deal involves the pair building a new 400 mile 500 kV transmission line, with a capacity of 750 megawatts, connecting northeastern Minnesota with Winnipeg, at a cost of $1bn split between the two utilities.
Manitoba Hydro is already an external participant with MISO, as a large hydroelectric system with some of the lowest electricity prices in North America.
“We can act as a rechargeable battery for the MISO market,” says Manitoba Hydro Division Manager of Power Sales and Operations David Cormie. “The arrangement we have with Minnesota Power is that they are going to invest in new transmission in the US, and Manitoba Hydro will invest in the transmission in Canada, and at the same time Manitoba Hydro is going to build new power dams that create more storage capability.”
The deal with Minnesota Power would use 51 per cent of the proposed line’s capacity, leaving the remainder available for other US utilities to do the same.
Huge “battery” to the north
The province lies at the centre of a 400,000 square mile watershed that drains from the Rocky Mountains to the west and Lake Superior to the east. The Nelson River drains north to Hudson Bay with an average flow at the sea of 115,000 cubic feet per second - eight times that of the Colorado River.
Manitoba's 1,000 feet of hydro-electric potential remains only half developed and two new hydro projects with associated storage planned for the Nelson River has created the opportunity for further interconnecting the Manitoba battery to MISO.
“We are able to able to operate our hydro system in a manner that takes energy out of the market when the prices are low, and returns the energy to the market in periods when the prices are high,” Cormie explains.
“But the new storage capability of our hydro system can only be useful if the transmission line capacity to the market gets bigger. So between the storage that Manitoba Hydro is developing and Minnesota Power’s willingness to build new transmission, we in effect are making the battery bigger, enabling more two-way trade in electricity.”
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