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Utility Asset Deferral

Zinc-Flow units can enhance the reliability and stability of electrical transmission and distribution (T&D) networks by reducing or deferring capital investments. Restructuring, continued demand growth, and low investment rates have conspired to make the management of the power grid not only more difficult in recent years, but also an area of growing concern for the future. Zinc-Flow units designed to support T&D networks are more concerned with the ability to quickly inject energy rather than replacing power generators' role of providing bulk-energy to the grid.

Zinc-Flow installations can help alleviate both the lack of transmission capacity and the stability problems that ensue during periods of high demand. Sited past a T&D bottleneck, they can provide a pre-positioned source of energy, which will allow the system to 'ride through' a few short-term peak demands during the month-postponing the need for an expensive upgrade on the line until a more sustained level of demand warrants an upgrade. An added benefit will be that the powerlines will experience greater overall-but less intense-use and wear through reducing overloaded lines (peak power transfers that rise above rated limits incur far more wear and tear on a line than pushing additional power through the line at night when the utilization is low).

Providing Utilities a means to better control the timing of their distribution system upgrades would be a windfall to these firms struggling to provide an ever-increasing level of reliability with diminishing resources. Because of the very wide demand needs, the loading on any particular powerline lines can be extremely variable with a low overall utilization. Currently, whenever such powerline becomes fully loaded-even for a short period of time a few times per month, the entire line's transmission capacity is then upgraded by about 1/3-a level deemed sufficient to preclude another upgrade for some time to come. Operating in this way without a storage component, the power transmission and distribution system must obviously be built-out so that it's capable of meeting the greatest demand under harsh conditions. However, as we've seen, it is not the entire system that reaches constraint, but single points in the system.

Coax

One strategy is to selectively defer a portion of these required upgrades-especially in the lower-voltage transmission and distribution where existing problems from underinvestment increase in incidence. By providing an additional 5 or more years of usability to the existing transmission equipment, scarce resources could be made available for other purposes, but more importantly, it would allow system upgrades to be planned around utility's schedule-not the other way around. The need for finding alternative solutions to this problem is apparent since the drivers for them-continued demand growth and aging equipment-show no fear of abatement; in fact, these point to even greater demand for alternatives.

Upwards of $13 billion is added to the capital infrastructure base each year: $3 billion in the transmission and $10 billion for the distribution market. This is needed to keep up with demand where over the last 10 years; demand growth in the United States has increased 20%, including a shift toward higher reliability. Meanwhile, the existing equipment continues to age-with much of the existing equipment approaching or surpassing its design life. A key strength Zinc-Flow units have over traditional solutions (expensive capital upgrades) to counter reliability and capacity problems is the multi-functional capability of the unit. Many times, it is not simply real power that is needed; rather, voltage control and even regulation are also needed. By providing such system stability support, storage technologies can also help to avoid the need for more expensive power stability and control equipment. The evaluation of storage technologies for this purpose has been undertaken for many years with many surprising findings in storage's favor. PG&E concluded in 1994 that a 1 MW, 2-hour duration battery storage system (10 year life) priced at $700/kW could enable the profitable deferral of one additional substation each year. In fact, Zinc-Flow can perform these tasks for a fraction of this cost.

Power Station

Included in this role for Zinc-Flow technology at the utility substation would be to provide grid-level, active power quality enhancement. This would require a MW scale unit, able to provide rapidly altering charge and discharge cycles to improve customer's power quality. Power quality is a growing problem for United States businesses; with estimates ranging upwards of $150 billion (US DOE) each year in lost production or damaged equipment from poor power quality. Surprisingly, more than 90% of these power quality disturbances are short-term, lasting for less than 2 seconds, and 98% last for less than 30 seconds according to the Electric Power Research Institute (EPRI). Placed at a substation, this larger system would subsume the role of substation backup power, effectively combining the two facilities in those places that deployed such a unit.

References:
Energy Storage Benefits and Market Analysis Handbook, Eyer, J., Iannucci, J., Corey, G., Sandia National Laboratories, Albuquerque, NM, 2004. Page 3. SAND2004-6177
Getting Electricity Where it is Needed, Edison Electric Institute, June 2001.
Cost Analysis for Energy Storage Systems for Electric Utility Applications, Abbas, A., Swaminthan, S., and Sen, R., Sandia National Laboratories, Alburqurque, NM, 1997,p.14, (SAND97-0443)