Energy resilience is a necessary requirement for a business or local authority to fulfil their operations and duties. A vulnerable energy supply threatens to harm every branch of local government and business activity.

In the worst of cases critical operations and services are disabled. And new hazards emerge as people find unsafe solutions of their own. The risk of house fires and carbon monoxide poisoning from candles and indoor generators both see an increase during power cuts.

Battery energy storage systems (BESS) are the technological solution, just like a trusty torch during a power cut. But complex sites and widespread constituent needs require ongoing backup preparation.

‘Energy audits’, reviews of energy likened to financial reviews, optimise backup power supplies by distributing backup power according to criticality and consumption.
Control systems are the ‘brains’ of the grid. They monitor energy use and identify and prioritise backup needs. They are that extra layer of backup planning for multi-faceted energy needs beyond the household power cut.

National and regional power outages are restored according to the geography of available backup methods. In April the Iberian grid was restored regionally as France-Spain interconnectors transferred power to northern Spain and the Morocco-Spain interconnector powered southern Spain before Spain-Portugal connecters repowered Portugal. Power restoration also stemmed from large black-start centres such as hydroelectric plants. While successful, the restoration process was not optimised for the countries’ energy needs and left many reliant on national infrastructure rather than localised backup.

Backup power is best distributed according to system criticality – the most important things need to stay on 24/7 while a minor delay in backup can be afforded with other things.

There is no universal assessment of what systems are critical and should take priority but there are 3 broad tiers:

- Tier 1: Critical loads. Requires 100% backup availability for non-negotiable power needs. Most non-negotiables lie within hospitals.

- Tier 2: Priority. Requires ~ 70% backup availability. Such as mainstream communications and notice boards.

- Tier 3: Discretionary load. Requires ~ 30% backup availability. Majority of systems to regain full operations.

A lot of discussions will be needed to decide what energy applications sit in each tier. For example, are traffic lights Critical or Priority?

Centrica Business Solutions recommends an energy distribution of 10% the backup supply for Tier 1 and 15% for Tier 2 given that fewer systems will be of greater priority. The remainder can be delegated to Tier 3 systems that make up the bulk of devices.
Optimised BESS are versatile and in line with the shift to renewable energy.

Where sites produce energy BESS store excess energy and distribute it at peak demand times, avoiding high energy costs and reliving the main grid. Battery systems prevent excess energy waste, allowing energy producing sites to ‘overload’ where production disruptions (low levels of sun, wind) are overcompensated for giving power generating sites security from losses.

Otherwise, other battery systems may lie dormant until needed during an outage.
In either case BESS need to account for overloading and future site expansions.
Site and or service expansion beyond existing energy backup capabilities creates vulnerability, energy backup systems should prerequisite site growth.