Enhancing the Gas Turbine Power Plant for Flexible Baseload PowerRobert Rapier
Gas turbine power plants are adjusting their traditional baseload power strategy to emphasize flexibility.
Following the start of the commercial electricity generation industry, most of the grid's electricity was produced by centralized power plants. When the industry was in its infancy, coal was the fuel of choice for this baseload power. Over time, however, nuclear power and the highly efficient gas turbine power plant began to make increasingly important contributions.
During the 20th century, these baseload power plants became larger in size and represented the foundation of the electrical grid. These plants were run at high capacity for maximum efficiency.
But the notion of traditional baseload power has begun to change in recent years, and that is causing a mismatch between the way many plants were originally designed and a future in which they will likely need to operate differently from power plants of the past 100 years. As a result, asset managers should prepare for a future where baseload power generation no longer resembles the traditional model.
There are multiple reasons for the shift away from traditional baseload power. One reason likely to continue to grow in importance is the incorporation of more renewables into the grid. According to the 2016 BP Statistical Review of World Energy, global consumption of wind and solar power increased by a factor of 10 between 2005 and 2015. Feed-in tariffs are encouraging this surge of renewable power, while simultaneously accelerating the retirement of coal-fired power plants and slowing the build-out of new nuclear power plants. These factors are all putting pressure on baseload power.
Coal plants that were previously baseload plants are being retired and replaced with very efficient gas turbine power plants. A gas turbine power plant operates with lower carbon dioxide emissions than the coal plants they are replacing, and, importantly, they have the ability to ramp up and down quickly in response to the new variable power sources that are being added to the grid.
Historically, baseload power could be supplemented with dispatchable power sources during high-demand periods. These peaking power plants were ramped up to 100 percent load as quickly as possible, run during the high-demand period, and then shut down. Today's power plant may instead run at a lower load and adjust output as needed. Power plants that were operated at baseload levels of perhaps 8,000 hours per year are now being called upon to run at 4,000 hours per year. Power plants that needed to be efficient at maximum load now need to be able to follow renewables. Unlike the baseload plant of the past, efficiency at 50 percent load is now far more important.
Instead of ramping up to full power quickly, more and more power plants need to dip down during the day but respond quickly if the output from renewables falls unexpectedly. Because the up-and-down cycles are more frequent, the maintenance requirements will likely be higher. When baseload plants are running fewer hours, making less electricity—yet requiring more maintenance—a different set of key performance indicators (KPI) is required for analyzing plant efficiency.
Countries with rapidly growing electricity demand like India and Pakistan will continue to depend upon traditional baseload power. However, the concept of traditional baseload power elsewhere is changing, especially in regions that have stagnant or slow-growing electricity demand but are adding significant amounts of renewable power to the grid. This is especially true in developed countries that are incorporating large amounts of wind power into the grid. Gas turbine power plants are ideally suited for the role of supplying flexible baseload power, but asset managers need to think strategically about how to adjust baseload power plant economics around a new set of KPIs.
While some power producers may wistfully wait for the baseload world to come back, the growing importance of renewables in the global power picture means they need to prepare for a future that is quite different from the past.
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