Large-Scale Battery Storage for Hospitals

Posted on January 22nd, 2018

Electricity is the lifeblood of modern society. It is neat, clean and simple to use. However, storing enough electricity to power a hospital for any meaningful period has been a challenge. The good news is that new battery technologies are making large-scale electricity storage practical and affordable. For hospitals, the capability to store and use large amounts of electricity on demand offers numerous advantages. The following describes potential advantages for hospitals and the technology of large-scale battery storage systems.

Financial Benefits of Large-Scale Battery Systems

A large-scale battery system allows a hospital to control the timing and amount of electricity it purchases, sells or stores. This capability enables the hospital to take advantage of a variety of opportunities to reduce electricity costs and generate revenues.

Reducing Demand Charges – In many locations, hospitals pay Demand Charges in addition to electricity use charges. Demand Charges represent the higher costs of distribution infrastructure and incremental generating capacity utilities incur to service large electricity users. Delivering a peak demand of 300 kW to a customer clearly costs the utility substantially more than delivering a maximum of 10 kW.

A hospital will experience its peak electricity usage when laundries, kitchens, operating rooms, labs and all other services are in full operation. This peak kW usage is measured throughout the monthly billing cycle and the maximum monthly kW figure is multiplied by a $/kW amount to calculate the Demand Charge. It is not uncommon for Demand Charges to account for more than half of a monthly electric bill.

Some utilities also charge commercial entities for excess reactive energy demand (KVAR) caused by poor facility power factor. Like the Demand Charge, utilities incur higher costs to serve large customers with a poor power factor. Fortunately, there is a way to reduce these charges.

Using electricity stored in a large-scale battery system, a hospital can minimize its peak kW usage (Demand Charges) and correct poor power factor conditions (KVAR) to save thousands of dollars on its electric bill. Furthermore, if stored electricity is generated by a renewable source such as photovoltaic panels, a hospital may be eligible for financial benefits beyond simply reducing its electric bill.

Reducing Time-of-Use (TOU) Charges – Some utilities charge higher rates for electricity depending on the time of day. These are called “time-of-use” (TOU) rates. TOU rates are intended to incentivize customers to use electricity at “off-peak” times when demand is lowest: late night and early morning weekday hours and anytime on weekends. Depending on the utility, TOU rates may be imposed or increased during months when outdoor temperatures increase and air conditioning loads drive electricity demand to the highest levels.

Unfortunately, a hospital’s highest electricity usage typically occurs between 8 AM and 8 PM when demand for electricity and TOU charges are high. Large-scale battery storage can help a hospital reduce TOU costs by “shifting” all or part of its load to off-peak hours. By recharging a large-scale battery system during off-peak hours, the hospital pays the lowest rates for electricity. It then uses that stored electricity during the day to minimize the hospital’s electricity purchases when TOU rates are highest.

Participating in Demand Response Programs – Most years, there are a handful of days when temperatures skyrocket and air conditioners strain to keep everyone cool. Rolling brownouts and blackouts are not uncommon on these days as utilities experience their annual maximum demand for electricity. Moreover, a major cost for utilities is having available electric generating facilities that typically operate less than 100 hours per year solely to meet the maximum electricity demand.

To minimize this huge cost, some electric utilities have programs to actually pay customers who voluntarily help reduce the peak demand by reducing their electricity use for a couple hours. These are broadly called “Demand Response” programs. The more a customer agrees to reduce its electricity usage (“negative demand”), the more the utility pays the customer. Hospitals can earn tens or hundreds of thousands of dollars per year simply for participating in Demand Response (DR) programs.

Large-scale battery storage systems make it easy for hospitals to maximize their income from Demand Response programs without the need to adjust operations to reduce electricity usage.

Perfect Power from Large-Scale Batteries

Hospitals and their patients depend on a sufficient supply of good quality electricity, however electricity from local utilities doesn’t always meet these needs. Brownouts, blackouts, voltage sags, unbalanced voltage, low voltage and autorecloser/fault clearing operations are some of the situations that can adversely affect hospital operations.

The conventional method for keeping critical hospital equipment and data centers operating during power problems is to use double-conversion uninterruptible power supplies (UPS) with support from backup diesel-generators for longer outages. This arrangement usually works well but it is inefficient, complex, and requires costly and frequent maintenance to ensure reliability.

Fortunately, large-scale battery storage systems have the potential to improve hospital power. Today, large-scale battery storage systems may not yet be directly backing up critical systems but their ability to provide electricity for an entire facility suggests it may not be long before they do. Especially when used in conjunction with combined heat and power (CHP systems), large-scale battery systems can provide hospitals reliable and resilient, high quality, environmentally friendly and, potentially, the lowest cost electricity.

State-of-the Art Large-Scale Battery Systems

There are two basic battery types currently used in large-scale battery applications: solid-state and flow batteries. Lithium Ion (Li-ion), Sodium Sulfur (NaS) and Nickel-Cadmium (Ni-Cd) batteries are the most popular solid-state batteries. Thanks to their proliferation and extensive use in electric vehicles, Li-ion batteries are the most popular choice for many large-scale applications.

Flow batteries, as the name suggests, typically utilize liquid electrolytes separated by a membrane rather than traditional solid plates. Current flow battery technologies include Iron-Chromium (ICB), Vanadium Flow (VFB) and Zinc-Bromine (Zn-Br) batteries. Recent articles from Forbes and the IEEE suggesting VFBs are the future of flow batteries will have that premise tested by a 2017 demonstration at a New York area hospital. The VFB installation is to provide 100kW of electricity for four hours to assist the hospital with demand reduction and backup power.

Income and Power

Large-scale battery storage systems have come of age and will only continue to improve as kW capacities increase, prices decrease and experience builds. The variety of opportunities to generate income while also improving power reliability and resiliency will make such systems an increasingly popular option for hospitals.

Contact ENGIE MEP for more information about large-scale battery systems and other energy efficiency measures for hospitals.

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