The Integrated Resource Plan (IRP) details how City Light anticipates meeting customer needs over the next 20 years with only a very small probability that they will face a necessity for brownouts during the most adverse conditions. Most new resources require significant lead time to build, so accurate forecasting and planning ahead of time is essential to be be sure that resources are in place when needed. In the past City Light has relied on spot market purchases of power to meet short-term shortfalls of power availability. This short-term power is often from gas-fired combustion turbines, which release greeenhouse gases that must be offset by purchasing Renewable Energy Credits (RECs). This will not be possible after 2035.
Seattle City Light presents a full IRP or an IRP Progress Report every two years to the Seattle City Council. In preparation for this, City Light conducts outreach meetings with interested parties. The biggest finding of the 2018 IRP Update is that they expect to meet power demands from 2018-2022 by reducing consumption through conservation investment, even with a growing population. After 2022, they project a need to purchasing more Renewable Energy Credits (REC) to cover more market purchases. Significantly increasing the conservation investments program to reduce the need for market purchases would require additional funds from rate increases, which the Seattle City Council has not favored.