Maximizing Power Cost Savings with Time of Day Pulping and Real Time Optimization, 2003 Fall Technical Conference

Alberta Newsprint Company purchases electrical power through the Alberta provincial power pool. Power prices in this market move with supply and demand. In extreme cases the price can change as much as two orders of magnitude over 24 hours.

A Time of Day Pulping (TDP) solution with Real Time Optimization (RTO) was implemented at the mill to achieve significant power cost savings. This system dynamically balances power price changes with TMP production capacity and paper machine production, determining the optimal number of refiner lines to run.

The Alberta power market was modeled using an innovative, statistical method that greatly enhances the effectiveness of the system. Instead of predicting the actual power prices, the ranking of the current power price in relation to the distribution of power prices that will occur over the next 72 hours is predicted.

This system has improved mill power price at a given price volatility by about 30%. The actual cost savings depends on the power prices/price volatility of the Alberta power market, but based on the price distribution in 2001 and 2002, a substantial savings in power cost was achieved.

Aggressive TDP systems generally increase pulp quality variability. In this case the system was implemented in conjunction with an advanced quality control installation. With advanced quality control, pulp variability was reduced by 30% despite the implementation of TDP.