Technology Corridor

Energy Storage Systems

How to reduce the cycling costs of conventional generation.

Energy Storage Systems (ESS) can provide significant benefits associated with reduced damage to fossil-fuel power plants if the ESS is used in such as way that it reduces start-ups or load-following/cycling. Though those benefits may not be well known, understood, or documented, they are real and ascertainable.

In recent years, many utility-owned thermal generation units, particularly older coal-, oil-, and gas-fueled units, have been forced to cycle, often on a daily basis. This is partly because of the commissioning of newer nuclear and large combined-cycle base load units, and partly because of increased power from efficient, low-cost merchant power plants. The cost of cycling these older fossil units is many times the costs used in making dispatch and planning decisions ().

We evaluated the cost of cycling for more than 200 units and found that cycling accelerates the wear and tear of many components of a generation unit, in mostly predictable ways. The increased cycling leads to higher maintenance costs and increased downtime, increased forced outage rates, higher heat rates, and shortened life expectancies. The evaluation also addresses dynamic heat rate effects-variation in generation fuel efficiency from variations in operating conditions, especially percent loading.