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Distributed Energy Storage Modeling Guide

Developed by R.W. Beck for Ice Energy, this 64-page guide is designed to assist utility planners and analysts in determining how to account for energy storage-equipped facilities as part of a utility's electric system analysis and planning processes.

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Modeling the Value of Energy Storage:

Breaking it down and adding it up.

Determining the value of distributed energy storage is considerably different for utility resource planners than modeling conventional power supply or demand-side resources.

The Ice Bear system requires consideration of technology-specific assumptions and the application of simulation and financial models to prepare reliable estimates and projections for impacts to electric system facility and operation costs produced by thermal energy storage technologies.

In other words, the value of storage is substantial. You'll just need a different set of tools. This guide can help.

Whether performing a standard utility pro forma analysis or a regulatory Total Resource Cost (TRC) analysis, it’s vital to consider a wide range of attributes when evaluating the Ice Bear system.

These include:

Value of Avoided Capacity

Individual Ice Bear units are installed a utility customer sites and are operated by the electric utility to shift customer loads from on-peak (daytime) periods to off-peak (nighttime) periods. By reducing electric system peak demands, future capacity requirements for the utility are reduced at significant cost savings to the utility through avoidance of generating unit additions or purchased power. Moreover, avoided capacity is greater than the achieved customer load reductions by the compound effects of avoided electric system losses, reduced capacity planning margins, and superior performance of the Ice Bear system during peak weather conditions.

Avoided Energy Production Costs

A fleet of Ice Bear units operating within an electric system will produce measureable impacts on the electric utility load shape, clipping peak period loads and filling off-peak valleys. This shift in energy will produce savings in electric system operating costs by reducing needs for high-cost, on-peak power and exchanging it for low-cost, off-peak power.  Other benefits may also be recognized as gains in electric system efficiency, improved utilization of generating assets, reduced use of fossil fuels, enhanced integration of renewable resources, and reduced air emissions.

Reduced Losses

Electric system losses are higher during peak load periods and are lower during low periods. The Ice Bear system counteracts this effect by reducing energy requirements during high-loss, on-peak periods and using energy during low-loss, off-peak periods, with the net effect being a reduction in total electric system losses. Moreover, changes in incremental or marginal losses, which are much higher than the average system losses, may be an appropriate measure of the impact on losses produced by the Ice Bear system.

Performance under Peak Conditions

A unique attribute of the Ice Bear system is its ability to assure demand reductions under high temperature conditions (capacity of the Ice Bear actually increases with ambient temperature). Additionally, the very high availability of individual Ice Bear units and the distributed nature of the Ice Bear system proved near 100% reliable capacity reductions. Conversely, generating unit performance actually drops during extreme weather events. When comparing the Ice Bear to avoided generating assets, the higher inherent performance of the Ice Bear should be considered.

Transmission & Distribution System Impacts

The Ice Bear system provides value by avoiding transmission and distribution system capital and operating costs. In some instances, avoided transmission and distribution upgrades can be significant, especially for electric systems facing major constraints on the electric grid. Regardless of the magnitude, transmission and distribution system impacts should be considered to assure a comprehensive assessment of the Ice Bear system.

Ancillary Services

The Ice Bear system will reduce ancillary service requirements of the electric utility or balancing authority. The Ice Bear system improves electric system power factor, thus reducing reactive power requirements. The Ice Bear system also reduces obligations for regulation, spinning, supplemental, and replacement reserves, and under certain operating schemes can provide these services to the electric grids. Avoided costs of ancillary services should be included when evaluating the benefits of the Ice Bear system.

Market Transactions

The Ice Bear system reduces electric utility loads during periods when market prices for power are high (peak periods) and uses energy during periods when market prices are low (off-peak periods).  During peak periods, the Ice Bear system will either reduce the quantity of high-priced market purchases the utility must make, or free up utility resources that can be then sold at a profit in the market. During the off-peak periods, the availability of market purchases tends to lower off-peak utility operating costs, thus lowering the cost of operating the Ice Bear system. The Ice Bear system can also take advantage of periods when market prices are severely depressed or negative.

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