By Dylan Bui, PE, Principal, Salas O’Brien

Hospitals were once designed around the assumption that utility outages would be rare, localized, and short-lived. That assumption no longer holds.

Today’s healthcare facilities operate in a different environment. Outages last longer. Public Safety Power Shutoff events occur with little warning. Extreme weather, seismic activity, and regional disruptions can affect both electricity and fuel supply. At the same time, hospitals themselves are becoming more dependent on electricity. Clinical technologies consume more power, building systems continue to electrify, and expectations around air quality and emissions are rising.

These pressures are changing how hospitals think about on-site power and how they define resilience.

In most buildings, a power outage is a disruption. In a hospital, it is a clinical event. Every interruption can affect patient care, clinical workflows, environmental controls, digital systems, and life-safety infrastructure. As a result, healthcare organizations are beginning to shift away from viewing on-site power solely as emergency backup and toward treating it as part of a broader continuity strategy.

From backup power to coordinated on-site generation

For hospitals, on-site power has traditionally been framed around emergency backup: the grid fails, generators start, and life-safety systems remain online. That function is non-negotiable.

But the conversation is expanding.

The question is no longer just, “What turns on when the grid goes down?” It is, “How should the hospital produce, store, manage, and prioritize power across normal operations, brief disruptions, and extended events?”

A layered system helps answer that question by assigning different roles to different technologies.

For continuity in the first seconds

At the onset of a disruption, the priority is stability. Battery energy storage or uninterruptible power systems can support voltage and frequency, allowing sensitive clinical equipment, IT systems, and controls to continue operating while the facility transitions away from grid power or moves onto backup sources.

This layer is not about carrying the hospital for hours. It is about making the transition nearly invisible, where even a momentary interruption can affect care, data, controls, or diagnostics.

For code-required emergency response

Emergency generators remain central to hospital resilience. Healthcare codes such as NFPA 110 and CSA Z32 require rapid power restoration to life-safety and critical systems, and generators are designed to meet those timelines.

Diesel remains the most widely accepted option because it is proven, code-recognized, and familiar to facility teams. But it also comes with fuel storage, fuel logistics, emissions, air quality considerations, testing, and maintenance demands.

Natural gas reciprocating generators can start quickly and eliminate the need for on-site diesel storage. They may support longer runtimes where gas services remain available, though they introduce dependency on utility gas infrastructure and carry their own emissions and maintenance requirements.

For longer outages and daily energy strategy

As outages extend, the conversation moves from response to endurance. Fuel cells, combined heat and power, or other steady generation sources can help carry base load, while batteries help absorb short-term changes in demand.

This is where on-site power begins to move beyond backup. These systems may support resilience during an outage, but they can also contribute to normal operations, demand management, energy cost control, and carbon reduction.

Fuel cells can provide quiet, efficient, scalable power with lower local emissions than many combustion-based systems. Natural gas or renewable natural gas units can reduce carbon impact, while hydrogen fuel cells offer a pathway to zero local emissions where low-carbon hydrogen and supporting infrastructure are available.

Combined heat and power can support continuous electric output while also producing useful thermal energy for heating, hot water, or other campus loads. It can improve efficiency and operating economics where hospitals have steady thermal demand, but the benefits depend heavily on load profile, fuel costs, emissions goals, and operating strategy.

For lower-carbon contribution and future firm power

Renewable sources such as solar PV and small wind turbines can reduce purchased electricity and support decarbonization goals where site conditions allow. Their role is usually contributory rather than primary because output depends on weather, available space, interconnection limits, and storage capacity.

The value of a layered strategy is that it gives hospitals more ways to respond. A brief grid disturbance may require only a seamless transition. A multi-hour outage may require load prioritization and fuel management. A prolonged regional disruption may require the hospital to operate more like an independent energy system.

That is why on-site power planning is moving beyond backup. The same systems that protect clinical continuity during an outage can also help hospitals manage daily energy performance, prepare for electrification, and adapt to changing emissions requirements.

Microgrids as an organizing framework

The growing use of multiple power sources has brought increased attention to microgrids. In healthcare, a microgrid is best understood as a control framework rather than a standalone technology.

A microgrid coordinates multiple on-site energy assets so they can operate together, isolate safely from the utility grid when necessary, and prioritize critical hospital operations during disruptions. It does not replace emergency power systems or eliminate the need for generators. Instead, it connects and manages the systems hospitals already rely on while allowing additional technologies to contribute strategically.

Within a healthcare microgrid, generators continue to provide code-required emergency power and extended contingency support. Battery energy storage systems stabilize transitions and maintain power quality for sensitive clinical equipment. Fuel cells and combined heat and power systems deliver steady base generation with reduced reliance on stored fuel. Renewable energy systems contribute supplemental generation where site conditions and climate allow.

The value lies in coordination.

Coordination also opens the door to a benefit beyond resilience: peak shaving and load shifting. As utility power becomes more expensive, on-site generation gives hospitals a way to manage electric bills alongside continuity. This matters especially in markets like California, where rate structures include demand charges tied to peak usage. Running battery systems during the day, when utility power is most expensive, reduces draw from the grid during high-cost windows. Recharging those batteries at night, when rates are lower, shifts consumption to periods with lower charges and helps facilities stay under peak demand thresholds. The same infrastructure that supports clinical continuity during an outage can also reduce operating costs during normal operations.

Regulatory developments are also making this approach more accessible. The introduction of 2023 NFPA 70 (NEC) Article 517.30(B)(4) reflects growing acceptance of healthcare microgrids within compliant emergency power strategies. Unlike previous code cycles, the new provision acknowledges microgrid applications in healthcare environments, where emergency power systems must support distinct life safety, critical, and equipment branches.

Coordination with Authorities Having Jurisdiction remains essential, but the shift signals broader recognition that hospitals can plan beyond a single generation source while maintaining regulatory compliance.

For healthcare organizations, this creates a more flexible path forward. Systems can be expanded in phases, adjusted as technologies mature, and adapted to evolving operational and regulatory requirements without compromising continuity of care.

What effective resilience planning looks like

Healthcare organizations navigating this transition successfully tend to begin with operational priorities rather than equipment selection.

That discipline matters because hospitals are being approached from every direction with potential solutions: generators, batteries, fuel cells, microgrids, renewables, and emerging technologies. Many of these options are valuable. But when teams are under pressure to improve resilience, reduce emissions, manage costs, and keep facilities running, it is easy for the conversation to move too quickly toward a specific technology before the larger operational need is clear.

Effective planning creates room to step back.

It starts by identifying which clinical functions must remain continuously operational, which systems can tolerate brief interruption, and how long the facility must sustain independent operation during a disruption. From there, infrastructure strategies can be phased and aligned with actual needs.

Early coordination is essential. Bringing utilities, engineers, facilities teams, and regulatory authorities into planning discussions early helps preserve flexibility and avoid constraints that become costly to address later.

Many organizations adopt phased implementation strategies. Rather than pursuing large, single-stage overhauls, they build resilience incrementally by modernizing generator infrastructure, adding battery storage, or introducing microgrid controls as part of ongoing capital programs. This approach allows systems to evolve alongside changing regulations, technology, and clinical demand without disrupting patient care.

Financial planning has become part of the resilience conversation as well. Hospitals now evaluate how on-site power investments affect downtime risk, fuel dependency, operational continuity, and future infrastructure costs rather than viewing power systems solely as compliance requirements.

The organizations that navigate this most effectively treat power as clinical infrastructure: systems that directly support continuity of care and require the same long-term planning discipline as any other critical healthcare asset.

Looking ahead

Hospitals operate in an environment defined by uncertainty. Grid conditions, clinical demands, regulatory frameworks, and sustainability goals will continue to evolve. On-site power systems must evolve with them.

Emerging technologies, such as microreactors, will also shape this conversation over time. They are not part of near-term healthcare planning, but they point to where resilience is heading: cleaner sources that can deliver firm power to large, energy-intensive campuses.

Layered strategies and microgrid frameworks offer a practical path forward. They build on proven technologies, preserve compliance, and create room for change. Most importantly, they support the fundamental mission of healthcare facilities: delivering continuous care, regardless of conditions outside the building.

In healthcare, resilience is ultimately measured by one outcome: whether care continues uninterrupted when conditions outside the hospital become uncertain.