The Yukon's two electrical grids are now one.

Premier Darrell Pasloski and Yukon MP Ryan Leef pushed the button at a symbolic ceremony Friday afternoon, though the connection went hot the night before.

The tie-in allows surplus energy from the Whitehorse-Aishihik-Faro (WAF) grid to flow north to the Mayo-Dawson grid, and vice versa.

Yukon Energy president David Morrison said the full benefits of the connection won't be seen until this fall, after the completion of the Mayo B hydro expansion and the addition of a third turbine at the Aishihik hydro plant.

"A major commitment in Yukon's Energy Strategy was the development of a territorial-wide electrical grid, and our government was fortunate to have the first project approved under the Government of Canada's Green Infrastructure Fund,” Pasloski said during a press conference.

"With the increase in Yukon's population, the need for reliable green energy is even greater.

"The Carmacks-Stewart Transmission Project is one of Yukon's Green Energy Legacy Projects.”

Leef said a few words on behalf of the federal government, which contributed $70.1 million toward the $120-million Mayo B hydro expansion and the $40-million line extension.

"The connection of Yukon's two major power grids gives more flexibility and stability to Yukon Energy's transmission system,” Leef said.

He pointed out phase one of the line extension from Carmacks to Pelly Crossing is saving about 25,000 to 30,000 tonnes in greenhouse gas emissions since taking Pelly off diesel generation in 2008.

Tying the two grids together is expected to cut the need for diesel generation by 40 per cent during periods of peak demand, Leef said.

"This is great news for Yukon and great news for our environment.”

With the Aishihik hydro plant off-line for the last three weeks to prepare for the installation of a new third turbine, the diesels in Whitehorse were running regularly.

The diesels in Dawson City have been running steady since late last year with the addition of the Bellekeno mine and mill to Mayo-Dawson grid, though they were silent this morning as the five megawatts of capacity at the Mayo dam were able to handle the demand.

The Mayo hydro facility, however, is scheduled to be shut down this evening for three months, to wrap up the expansion that includes two new five-megawatt generators.

But with Aishihik back on line as of Sunday afternoon, and with the new single grid, there is sufficient hydro generation available to carry the load on both grids without diesel, according to the numbers.

Demand on the Mayo-Dawson grid this morning, for instance, required approximately 4.8 megawatts of generation, while demand on the WAF grid was requiring 40 megawatts, for a total demand of 44.8 megawatts.

When Aishihik came on line yesterday, the available hydro capacity on the WAF grid went from 38 megawatts to approximately 68, or significantly more than required to meet peak demand on both grids.

"In my mind, it is a big investment on the Yukon's future,” the Yukon Energy president told reporters of connecting the two grids and expanding the Mayo hydro facility.

"These are legacy projects that will continue to provide benefits to Yukoners well into the future, and that is what I am pleased about.”

Morrison also emphasized neither of the projects would have been been possible without financing from both the territorial and federal governments.

Yukon Energy employees, he added, are also due a great deal of credit for pulling together and making the two projects successful.

Having a unified grid not only provides the benefit of sharing surplus green energy, but it also increases flexibility in developing new generating capacity, he explained.

Morrison said with a unified grid, adding capacity anywhere benefits all electrical consumers, so that improvements in capacity are no longer restricted to either the south or the north grid.

Among the energy projects being pursued by Yukon Energy is a wind farm on Ferry Hill which overlooks Stewart Crossing, where the two grids were connected.

"The board of directors regards this last development, the integrating of the two grids, as fundamental to Yukon's Energy future,” Piers McDonald, chair of Yukon Energy's board, said Friday afternoon.

"It was a piece of the puzzle that had to be done,” said the former Yukon NDP government leader.