Contracted Power
Typically, wind generated electricity is sold to an electrical utility, or to the operator of an electricity grid, under a multi-year contract which is heavily in favour of the windpower company. Typically, the buyer must accept, up to the contract maximum, whatever amount is being produced by the windmills with no minimum and no penalties for low supply. Contracts running twenty years or longer are usual.
Wind electricity is purchased by utilities or grid operators largely for the favourable image they expect this creates with their customers, who believe it satisfies some environmental objective. “Green power” and all that. It thus can be seen as an exercise in public relations.
The cost of wind electricity is really two separate expenses: _one part as a cost of purchased power comparable to reliable power obtained from some other outside source, _with the remainder an expense to be charged to a public image account or public relations account — call it what you will. Such would reflect the actual situation and be an honest accounting of this expense for the purchaser.
Were this electricity being generated by some other means, would the buyer pay full price for an erratic and unreliable supply? No, the buyer would not. It would pay a discounted price precisely because the supply is unreliable and erratic. So the amount which ought to be charged to a public image account is that much higher per unit than one might at first anticipate.
Windpower is erratic and unreliable, for some days very little gets generated. On some days light breezes barely cause the windmills to mill. This is particularly true when a cold high pressure system sits over a wide area for several days in the depths of winter, air temperatures very low. Having becalmed windmills just as annual peak demand occurs is not a good combination.
Brrrr…When it’s really cold
A recent example is the Alberta Electric System Operator which has responsibility for running the electricity grid in Alberta, sourcing supply from several companies who produce electricity. On January 12th of 2024 it issued an alert that the grid was in danger of being unable to meet surging demand during a very cold run of days. Total demand was a new high of 12,384 Mw. Part of its usual supply are renewables contracted for about 6,000 Mw but who were supplying less than one percent of that amount. The frigid still air of an Arctic high pressure cell can have that effect.
A similar earlier instance was the experience of New Brunswick Power in the last week of 2007. It had a 25 year contract with a windpower producer to supply up to 300 Mw of electricity, but during several very cold days with very little wind was being delivered only 6 Mw. This was at the time of peak annual consumption, which typically is on the coldest days of winter. Yet, the utility could not count on supply from the windpower producer.
The fault here lies with the utility signing such a one-sided contract. It clearly should not have. Instead, it should insist on a steady supply of stipulated amounts, either from the windpower company itself or from an intermediary to whom it supplies unreliable amounts but who then must supply predictable steady amounts to the utility. Likely this would entail the intermediary having a gas turbine generator to even up the unreliable output of the windmills. [Call them wind turbines if you prefer.]
Surely, the utility should put its own needs foremost and not simply go along with what a windpower producer is able to provide, whatever that might be, whether much or hardly any at all. Calm cold weather in the middle of winter to be expected after all. Lack of foresight is no good excuse for signing supply contracts with no minimum amounts stipulated.