Modifying Conventional Power Plants for a Changing Industry

As renewable energy is becoming more prevalent in the power sector, conventional thermal plants must evolve to remain profitable and avoid closure. Modifications to these existing facilities must be made to raise ramp rates, minimize the time for starts and stops, and to achieve a lower minimum loading. Reaching these goals to remain profitable in a competitive and evolving market can be achieved by making operational adjustments, modifying control systems, and by performing major upgrades.

According to the International Energy Agency (IEA), renewable energy is the fastest growing part of the power sector and is projected to meet 30% of all global power demand by 2023, which is an increase from 24% of demand met in 2017. These renewables include generation from hydropower, wind, solar photovoltaic (PV), and bioenergy. This growth of renewable energy, along with an increase in installed global energy storage, makes the power sector much more competitive for existing conventional thermal plants.

Generation from renewables such as solar and wind constantly changes, and with varying load demand, grid operators prefer power plants with a high ramp rate to provide stability to the grid. Thus, plants are preferred that can provide additional or curtail load at a similar rate to variations in generation by renewables. As the amount of installed renewables rises, conventional thermal plants who have strived to raise their ramp rates will be preferred over plants that have not. The IEA Clean Coal Centre discusses how some coal-fired power plants have increased their ramp rates up to 5%/min with control system changes and tuning.

Along with the importance of raising ramp rates, reducing the start and stop times for conventional baseload power plants is also very important in the evolving power sector. Baseload power plants that have the ability to start when profitable and stop when a continued operation is no longer profitable will have an advantage over plants that have extended start and stop times. Because of the increase in installed renewables, without an equivalent increase in energy storage, grid operators in areas such as Germany and California have to deal with excess energy production during times of high wind speed and high solar irradiance. During periods of excess energy production, grid operators in these areas have had to give away or pay neighboring countries/states to take the energy. Having the ability to start and stop faster will minimize the time power plants have to operate during these conditions as the price per MWh paid to the plant is often negative.

Achieving a lower minimum loading can also help conventional power plants minimize losses during periods where the price per MWh is negative. Often, the amount of time where it is not profitable to continue operation does not warrant a shutdown of the power plant. Grid operators will prefer plants with lower minimum loading to remain in operation during these periods to minimize stops and restarts when demand returns, and to minimize cycling of peaking units.

Raising ramp rates, reducing start and stop times, and lowering the minimum loading are goals all conventional thermal power plants should be striving to achieve in this changing power sector. As the industry continues to evolve with the ever-increasing installation of renewables, striving to meet these goals will ensure your plant remains profitable in such a competitive market. FCS can help to ensure your plant is able to meet these goals.