Dispatchable Loads

As with dispatchable generators, dispatchable loads must be able to adjust their power consumption in response to instructions from the IESO. These instructions are called “dispatch” instructions, and the loads are “dispatchable”.

The IESO issues dispatch instructions to dispatchable loads for each five-minute interval of the day, and the loads must be equipped to receive and respond to dispatch instructions from the IESO 24 hours a day, 365 days a year.

The dispatch instructions to reach a specific level of consumption will be based primarily upon the load's bids to purchase electricity at specific prices relative to the bids and offers from other facilities. For example, a load may submit a bid to purchase 20 megawatts of energy if the price is $25/MW or below, but may not wish to purchase if the price is higher than $25. If there is available energy that costs $25 or less, the load will receive dispatch instructions from the IESO telling it how much energy to withdraw from the grid. If the only available energy costs more than $25, the IESO will send dispatch instructions telling the load not to withdraw the 20 megawatts from the grid. The dispatch instructions must also take into account the facility's ability to adjust to its energy consumption levels.

Non-Dispatchable Loads

Non-dispatchable loads consume electricity in much the same way as you do at home. They simply draw electricity from the IESO-controlled grid as needed for their equipment. They agree to pay the wholesale market price for electricity at the time of consumption, regardless of what that price might be. Examples of non-dispatchable loads include municipalities, hospitals, and large factories. Wholesale prices for non-dispatchable loads are set on an hourly basis.

Some non-dispatchable loads act as distributors; that is, they take electricity from the IESO-controlled grid and distribute it to retail consumers at a lower voltage. (Your local municipal utility is an example of a distributor.)

Non-dispatchable loads account for most of the energy consumed in Ontario.