Method for Analyzing the Value of Distributed Energy Storage at the Facility Level – Step 2: Non-Energy Considerations

Figure 1 shows the current step in the evaluation methodology…

Figure 1 Showing the current step in the methodology for evaluating a facility level energy storage deployment.

Continuing with the example of the software company, the appropriate application determined in the previous steps is Demand Charge Management. With this in mind only energy storage devices that supply sufficient energy at a power rating enough to significantly reduce the facility’s peak power demand will be considered. This eliminates from consideration low energy/power rated devices and devices that focus on power quality (such as flywheels and capacitors). Of course, all facilities are unique and low energy/power rated devices and power quality devices maybe highly valuable elsewhere. It is also important to note that energy storage device manufacturers are constantly looking at ways to increase the breath of applications their devices can address.

Outside of the energy requirements for the facility there are many other factors that must be considered to choose the appropriate energy storage technology. One important factor is the amount and type of land available for an energy storage implementation. Considering land use, the following technologies were not be considered feasible at the software company:

• Pumped Hydro energy storage - large amounts of land are required for the two reservoirs, one of which must be elevated significantly above the other.
• Gravity Power energy storage - even though there may potentially have been several acres of land available on the facility’s property, this technology is not considered feasible because of the large upfront investment in digging the 500 m deep storage shafts.
• CAES using underground caverns - it is not known if there is a large underground cavern which could support CAES. However, it is unlikely that the facility owners could be convinced to initiate the geologic survey required to determine if there is a viable underground cavern.
• CAES using underwater airbags - though there is a reservoir located near the facility, the reservoir is used to supply drinking water to a nearby city and the mean depth is 3.8 m. For this reason it is not likely that the reservoir can be used for CAES using underwater airbags.
• CST - there is not likely sufficient land and sufficient solar access to support a concentrated solar thermal electricity generation and storage system.

Clearly an appropriate energy storage device would be one with a small footprint that does not rely on unique geologic features. Though it is understood that some changes to the facility may be required to support energy storage technologies, it is not likely that the changes required to add sufficient thermal mass to the building will be considered. For this reason, adding a Trombe wall or some other type of thermal mass is not considered viable.

It is important to reiterate that all the above considerations apply only to the particular facility in question (the software company). Every facility is different and something inappropriate for one facility may be applicable to another.