For the first time in a good while, Yukon Energy is burning diesel as a primary source of power generation, says the corporation's spokeswoman.

Janet Patterson explained this morning diesel generation was required Monday during peak demand at breakfast and supper time, and again this morning, as two of the hydroelectric generators are down, including the primary fourth wheel.

That wheel, which generates half of the total hydroelectric capacity at the Whitehorse Rapids Dam, was taken off-line last week after a sticky valve caused a power outage on Thanksgiving Sunday. The number three turbine was taken off-line early Monday morning, following a brief four-minute outage at 1:10 a.m.

As a result, the diesel generators were required and commercial consumers of secondary surplus power were given their 24 hours' cut-off notice.

Patterson said the 22 consumers of secondary power will be off the system prior to this evening's peak demand period, though some diesel generation will likely still be required.

Experts from a Wisconsin electrical company which manufactures parts for hydroelectric generators will be in Whitehorse Wednesday or Thursday to check out the numbers three and four turbines, Patterson said.

With a surplus of hydroelectric power on the grid after the Faro mine ceased operations in 1998, Yukon Energy offered large energy consumers a chance to buy surplus hydroelectric power at a discount rate.

In many instances, it offset the need to burn diesel or propane as a source of heat. There was a condition, however, that the consumers had to maintain a primary electrical feed, and their regular source of heat just in case they had to be cut off surplus power.

Whitehorse General Hospital, for instance, is a large consumer of secondary surplus power.

So too is the Yukon Brewing Company.

Company president Bob Baxter said this morning his business invested in the necessary equipment to take advantage of cheaper electricity, understanding that there would be times when it wasn't available.

Yukon Brewing doesn't use the electricity for its main source of heat, as the building is heated primarily by capturing and redistributing heat from hits refrigeration units, Baxter pointed out.

He said the brewery uses the bulk of its electricity for its electrical boiler to make beer, though it has an oil-fired boiler as well.

If this was the middle of January when demand for beer drops off somewhat, Yukon Brewing might consider not brewing for a couple of days to avoid the greater cost of using the oil-fired boiler, Baxter pointed out.

But right now, he said, the brewery will just keep on brewing.

Baxter said once the Minto mine comes on-line, the company expects there will be less available surplus power, especially in the winter months.

Fortunately for Yukon Brewing, he said, demand for beer is greatest in the summer, when demand for electricity is at its lowest and the amount of surplus hydro is at its highest.

Patterson said recently that Yukon Energy was hoping to have the mine and Pelly Crossing tied into the grid by the end of this month.

Meanwhile, the cause of the lengthy blackout on Thanksgiving Monday remains a mystery.

Patterson said staff at the publicly-owned corporation have checked and rechecked, and cannot find any explanation at their end.

Yukon Energy is primarily responsible for power generation in the territory, while Yukon Electrical Co. Ltd. is primarily responsible for distributing the power.

Jay Massie, operations manager for Yukon Electrical, said today that last week, staff at his shop have checked and rechecked their equipment. They couldn't find anything at their end to explain the power outage on Thanksgiving Monday, which lasted more than five hours for some.

Yukon Electrical, he pointed out, did not have to make any repairs to get the power back on.

Yukon Energy is also in the midst of seeking a new three-year air emissions permit for its diesel generators. The existing permit will expire Dec. 31.

The company submitted its 180-page application to the Whitehorse office of the Yukon Environmental and Socio-economic Assessment Board late last month.