Module: Baseline Development
Redundant Energy and Water Systems
A redundant system refers to an onsite system able to supply energy or water to a critical load in the event of an energy or water utility disruption. A backup generator, UPS, building-integrated PV system, or microgrid with PV and battery storage are all examples of redundant energy systems to a utility supply. To be considered redundant, an onsite energy system must not be reliant on grid power to function and supply the critical load. Redundant water systems may include onsite water cisterns connected to a critical load, portable water tanks, or reverse osmosis purification systems.
The TRN refers to first and second redundant systems to account for loads with two tiers of redundancy as a way to manage risk (e.g. a battery storage system and a generator). A second redundant system is one that is independent of the utility system and, preferably, independent of the first redundant system, meaning it relies on different hardware from the primary system so the two systems are not vulnerable to a common cause of failure.
This action characterizes the baseline conditions of energy and water systems that enable critical loads. Baseline conditions are examined in terms of the site’s preparedness to respond to disruptions, redundant systems in place, robustness of system design, and plans for rapid recovery.
Data collection for this action focuses on baseline conditions of redundant energy and water systems, as sites typically have greater influence over these than they do over primary energy and water supply infrastructure. This data is used to inform risk scoring in the Risk Assessment module. Data is also gathered on the condition of the primary energy and water supply systems. While primary supply system characteristics are not explicitly considered in risk assessment, understanding the utility’s preparedness to respond to emergencies, redundancies built into the supply system, robustness of system design, and whether the utility is positioned for rapid recovery, can help identify additional solutions that would enhance site resilience.
To complete this action, consider:
- Are existing energy and water systems designed to meet current and future mission requirements?
- Is current energy and water resource use optimized to meet those requirements?
- Do redundant systems exist where they are required?
- How long can the critical load requirements be met with the current redundant systems?
- Are existing systems operated and maintained in a way that provides assurance they will work reliably when they are needed?
- Are the systems configured to facilitate reliable start-up?
Data Inputs Needed
- Existing redundant systems and design attributes
- Redundant system engineering and process flow diagrams
- Redundant system O&M procedures, schedules, and logs
- Past efficiency assessments of facilities with critical loads
- Energy and water supply infrastructure diagrams and condition assessments
- Daily energy and water load estimates (output from Action 2)
- Primary supply system one-line diagrams and condition assessments
Outputs of This Action
- Redundant system characteristics required to model risk in the Risk Assessment: Action 3
- Primary energy and water supply system conditions
- Dependency mapping between critical loads and primary energy and water supply systems
- Existing redundant system runtime duration relative to mission requirements
Establishing baseline conditions of energy and water systems involves:
- Characterizing the condition of redundant systems on critical loads
- Comparing the design capacity of redundant systems to meet the critical energy and water requirements
- Characterizing primary energy and water supply system conditions and establishing dependencies between critical loads and those systems.
Baseline conditions are established using data gathered through Action 1: Collect and Review Baseline Documentation, and through interviews with mission owners and site operators as described in Action 2: Establish Baseline Energy and Water Requirements. Observation and system auditing may also be required to fill data gaps.
Redundant System Conditions
The redundant system characteristics established in this action are the primary input to the Risk Assessment module. Mission owner interviews are often a prime source of information on the systems that back up their critical functions. Firsthand observation of redundant systems is also important to verify data such as age, system capacity, and connected circuits. Finally, site operations personnel in facilities management and emergency planning organizations can provide helpful sources of information on O&M practices, COOP or recovery plans, and training on the operation of these systems. Specific questions for these site operations personnel are found in the TRN Resource: Interview Questions.The information on redundant energy and water system conditions focuses on four areas: general system, design, reliability, and configuration.
- General: defines the state of any redundant systems for each critical load identified
- Presence of one or more redundant systems for energy and water loads
- Age and general condition of redundant systems
- Planned upgrades to redundant systems to improve performance
- Design: defines the design intent of systems, defines operating parameters and environmental conditions under which the system is designed to meet its operational intent
- Relevant hazards and threats the system and components are designed to withstand
- Design capacity of the system
- Reliability: defines the operation, maintenance, and testing of the system and other reliability management measures
- Maintenance and testing programs followed
- Written procedures and schedules in place
- Maintenance and testing logs
- Personnel training on maintenance, repair, testing, start-up, and use of system
- Onsite parts supply for system repair
- Priority restoration and refueling agreements in place
- Configuration: defines the state of the operating processes, procedures and plans in place for the redundant system
- Automatic versus manual start-up configuration
- Documentation of start-up procedures
If the critical load has two systems that provide redundancy, the same data above is collected for both the first and second redundant systems (e.g., a critical load with second backup generator in the event the main generator fails). Data is also gathered on the connection between first and second redundant systems and the use of the second system for emergency only or normal operations also.
Use the tables in the Baseline Development Action 3 Worksheet: Redundant System Conditions to document the key pieces of information on the first redundant system, and a second redundant system supporting critical loads, as appropriate.
Redundant System Design Capacity Versus Requirements
Ideally, redundant systems are designed to meet the critical energy and water requirements of a facility. This includes consideration of system sizing to meet current and future demand and the availability of fuel onsite (if required) to supply a critical load for as long as it is needed. The following data gathered in Actions 1, 2, and 3 provide the basis for establishing system design capacity relative to uptime or runtime requirements:
- Critical function duration requirement: number of days the critical load must run continuously to support the critical function, determined through mission owner interviews
- Daily energy or water requirement: daily energy (in kWh per day) and water use (in gallons per day) for each critical load, as established in the Energy and Water Daily Use Estimation worksheet; typically, peak requirement is used to determine the number of days the critical load can be met with the redundant system
- Redundant system design: total capacity of the redundant energy and water systems, as documented in the Redundant System Conditions worksheet; for generators, data on system capacity (kW), fuel storage capacity (gal), generator combustion efficiency, and fuel type will be required
- Number of days the critical function can be met: system capacity is compared to the energy and water daily demand to determine the number of days the load can be met.
For example, a peak water demand of 7,000 gallons per day with a 21,000-gallon storage capacity can provide 3 days of water to a critical load. If the mission requirement for water is 3 days or less, the requirement can be met. Calculations for the runtime of backup generators require consideration of other factors, including system efficiency and fuel type. For example, a critical load with an energy demand of 2,400 kWh/day supported by onsite diesel storage of 1,000 gallons can provide 5 days of energy to a critical load (assuming generator efficiency is 30%). If the critical function requires that load to run for less than 6 days of runtime, the current solution would be adequate. If a longer period of uninterrupted power is required, it would not meet the mission requirement. Expected load growth stemming from future mission growth and resulting additional buildings or facilities should also be considered in determining load requirements. Use the TRN Resource: Generator Fuel Analysis to establish the number of days current redundant generator systems will be able to meet critical energy loads. Then compare the current state to mission requirements.
In addition to understanding energy and water requirements, the resilience planning team should also understand how efficiently energy and water resources are used by the facilities that house critical loads. If facility energy and water systems are not optimized or are inefficient (e.g., building automation system controls without setbacks, low efficiency hot water heating equipment, high water consuming fixtures), the loads on redundant systems may be larger than necessary. When redundant systems are operating, fuel supplies will be depleted faster. This may influence the system’s ability to meet mission requirements. Further, if redundant systems are lacking and new systems are to be installed, those systems may be oversized to accommodate inefficient loads, resulting in higher capital and operating costs. Site resilience planners should combine facility efficiency audits with in-field observations of redundant systems to identify load reduction opportunities. The team should also account for any planned upgrades that would increase building system efficiency when estimating load requirements.
Primary System Conditions and Critical Load Dependencies
Sites may or may not have operational control or influence over their utility infrastructure. This will vary depending on the size of the site and status of utility privatization contracts. Whether or not a site has direct control over the infrastructure, it can be helpful to understand what primary energy and water systems supply critical loads, as well as the condition of those systems.
The resilience planning team will establish the dependencies between critical loads and the primary energy and water supply systems using resources gathered in Action 1. This action might include GIS or other site maps, facility locations, and major energy and water infrastructure locations (i.e., distribution lines, interconnection points, substations, transformers, water treatment facilities, pumping stations, water towers, wells, lift stations), to map which infrastructure supplies which facilities.
Once the critical supply sources are understood, assess the baseline conditions of these systems in terms of:
Record Resilience Gaps
Now that the actions in this module have been completed, consider the resilience gaps identified and whether they need to be documented in the Site-Level Planning Action 5 Worksheet: Recognize Resilience Gaps. Refer to the TRN Resource: Resilience Gaps Checklist for a summary of key areas of this module that may reveal resilience gaps
- Design for robustness to withstand the most likely hazard and threat scenarios; design to meet current and future capacity requirements
- Availability of redundant feeds in the supply system
- Documented O&M practices and logs of performance, known problems with resource quality or delivery that may affect system reliability
- Documentation of contingency plans and parts inventories to determine recovery times for partial and full recovery.
Questions for site operations personnel and utility providers in the TRN Resource: Interview Questions will also help establish the primary energy and water system conditions.