Demand-Side and Supply-Side Load Management: Optimizing with Thermal Energy Storage (TES) for the Restructuring Energy Marketplace

The current and future restructuring energy marketplace represents a number of challenges and opportunities to maximize value through the management of peak power. This is true both on the demand-side regarding peak power use and on the supply-side regarding power generation. Thermal Energy Storage (TES) can provide the flexibility essential to the economical management of power. In large industrial applications, the added value of TES has been demonstrated, not only in managing operating costs, but also in delivering a net saving in capital cost versus conventional, non-storage approaches. This capital cost saving is often realized in situations where investments in chiller plant capacity, or in on-site power generating capacity, are required. On the demand-side, TES has long been used to shift air-conditioning loads and process cooling loads from on-peak to off-peak periods. In today's and tomorrow's restructuring energy markets, price spikes are increasingly likely during periods of peak power demand. TES is performing an important role, especially when coupled with a proper understanding of modern TES technology options. The inherent advantages and limitations of the available TES technology options are briefly reviewed and discussed. Examples of existing large TES installations are presented, identifying the TES technology types they utilize. The applications include industrial facilities, as well as universities, hospitals, government, and District Cooling utility systems. The power management impact and the economic benefits of TES are illustrated through a review of several TES case studies. Combustion Turbines (CTs) are a common choice for modern on-site and utility power generation facilities. Inlet air cooling of CTs enhances their hot weather performance and has been successfully accomplished for many years, using a variety of technologies. In many instances, TES can and does provide a uniquely advantageous method of optimizing the economics of CT Inlet Cooling (CTIC) systems. TES systems can achieve low inlet air temperatures, with resulting high levels of power augmentation. The TES approach also minimizes the installed capacity (and capital cost) of cooling systems, as well as limiting the parasitic loads occurring during periods of peak power demand and peak power value. Chilled water, ice, and low temperature fluid TES systems are all applicable to CTIC. The inherent pros and cons of each TES type are discussed. Sensitivity analyses are presented to explore the impact of cooling hours per day on capital cost per kW of power enhancement. Case histories illustrate the beneficial impact of TES-based CTIC on both capital cost and operating cost of CT power plants. TES-based CTIC is advantageous as an economical, peaking power enhancement for either peaking or base-load plants. It is applied to both new and existing CTs. TES is projected to have even greater value in future restructuring energy markets