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Improving community readiness for evacuations with electric vehicles

Electric Vehicles (EVs) are moving onto the U.S. market quickly, with a predicted one million EVs hitting the road by 2020 (Shepardson, 2017). EVs have been gaining popularity for several reasons, from lower maintenance costs to reducing the amount of imported petroleum and eliminating carbon emissions (Li et al., 2015). EVs convert 59–62% of the electric energy from the grid to power at the wheels, compared with 17–21% for gasoline vehicles. With no exhaust, EVs emit no pollutants, provide stronger acceleration, and require less maintenance. In the United States, the biggest contributor to carbon dioxide emissions is now the transportation sector, making EVs an important part of the overall solution toward reducing those emissions (U.S. Energy Information Administration – EIA – Independent Statistics and Analysis, 2017).

However, alongside the many benefits of EVs there are a few drawbacks. EVs do not have a long driving range (defined as the total distance an electric vehicle can travel in miles after receiving a full charge). On average, they can go between 62 and 107 miles, except the Tesla models, which range between 234 and 270 miles on a single charge. The recharging time of EVs can take from thirty minutes to several hours, requiring extended access to an electric charging station.

Charging stations are not as readily available as gas stations. In 2017, the number of publically accessible charging stations in the United States surpassed 15,943, totaling more than 42,550 outlets (Electric Vehicle Charging Station Locations, 2017). (These numbers may be different by the time of publication due to the frequency of updating.) In comparison, as of 2012 there were 114,000 gas stations in the U.S., according to the U.S. Census. While private charging stations offer a bit more flexibility, without access to readily available public charging stations, the locations that an EV can reach are limited.

One implication of a lack of charging stations that has not been discussed or explored fully is how EVs will fare during an evacuation from a location such as the Florida Keys, or with a long power outage after an event such as a tropical storm or a hurricane. Natural disasters often cause electricity outages, which could leave EV owners unable to evacuate from a dangerous area, or without transportation for long periods of time following the outage event. As of yet, public policy regarding natural disasters does not take into account the growing number of EVs or provide contingency plans for EV drivers unable to follow the same evacuation plans as owners of gasoline vehicles. This includes emergency management at the local, state, and federal level (FEMA), public utilities, and the host communities. For instance, Florida's Division of Emergency Management publishes regional evacuation studies, none of which take into account EVs. In contrast, gasoline vehicles are accounted for by Florida state law (Florida Statues 526.143), which requires that certain gasoline fueling stations located near major evacuation routes must be capable of operating using backup power. It is one of the aims of this paper to investigate this discrepancy and explore ways in which it can be corrected.

When natural disasters like wildfires or flooding strike, thousands of people may be told to pack their belongings into their cars and evacuate. Emergency planners base evacuation strategies on the assumption that people are driving gas-powered cars that can be refueled at any gas station—but with more people driving electric vehicles (EVs), new challenges arise.

That's why a team of researchers at the University of California, Santa Cruz, UC Berkeley, UC Davis and UC Merced published a study in IEEE Electrification Magazine that outlines key challenges and recommendations for city planners to best support EV drivers during an evacuation. Challenges include the limited network of EV chargers and the vulnerability of the chargers that do exist to power outages, while opportunities for improving community readiness include EV-friendly evacuation routing and strategic positioning of mobile charging ports before a disaster strikes.

Community-engaged research...To study EV evacuation readiness, a team of researchers across several UC campuses came together, bringing expertise in electrical engineering, mechanical engineering, traffic theory and renewable energy. Keith Corzine and Leila Parsa, professors of electrical and computer engineering at the Baskin School of Engineering, contributed expertise in power and energy systems and EVs.

The team set out to understand how the growing number of EV drivers might be impacted during natural disaster evacuations. They were particularly motivated by wildfires, with Santa Cruz having recently experienced the 2020 CZU Lightning Complex fire that burned more than 85,000 acres (344 square kilometers), but the research applies to any natural disaster, including earthquakes and flooding.

The team partnered with Mariposa County in the Sierra Nevada foothills to meet various stakeholders, including emergency planners, companies that made EV chargers and electrical utility representatives.

"From the beginning, we wanted to connect with communities," Corzine said. "Our first idea was to explore what kind of recommendations we could make to a community to help them decide what they should invest in, like batteries, chargers or renewable energy sources so that during an evacuation, they could use these resources."

To understand a community's readiness for evacuation, the team developed a process for scoring preparedness by looking at what charging infrastructure is in place, what kind of mobile backup power might be available, what transportation routes look like and what engagement exists between emergency response officials and the community. The team has a forthcoming study on this topic, which city planners and emergency response professionals could use as a resource in their own communities.

One major challenge the team identified was the availability of charging infrastructure and recharging times, especially as some communities have few or no fast chargers. Power outages at charging stations present another vulnerability, particularly considering some electrical utility companies implement public safety power shutoffs when the risk of wildfire is high. EVs left behind during the evacuation could pose additional risks, because if their lithium batteries ignite, resulting fires are intense and toxic.

Preparing for the future with EVs...The researchers examined typical energy charging infrastructure to assess what charging needs might be during an evacuation, considering there may be a surge of energy needed at charging stations and many cars may be traveling along just a few roads. This brought together a range of factors like the energy efficiency of vehicles, the location of chargers and the evacuation distance. Based on a benchmark standard power system, the UC Santa Cruz team examined how power flow might be optimized if a failure like a blackout occurs at one point in the system, in order to minimize damage.

This analysis led the team to several insights. First, mobile charging stations can be used to augment charging infrastructure during periods of high demand, and the team's power flow analysis can help guide communities about how many of these chargers are needed and where they should be placed.

The team members at UC Berkeley and UC Davis took the lead on traffic simulations and found that some communities might experience major traffic congestion when thousands of evacuees converge on a few major corridors with EV charging stations. They found that in some situations, emergency planners should recommend different people take distinct evacuation routes, even if they are sometimes longer, based on the real-time conditions and needs of their EVs.

Their research also highlighted the necessity of educating communities on safe evacuations. For EV owners, one particularly important message is straightforward: charge your EV to 100% if there's a high chance of a wildfire, flood or other hazard.

As part of the larger project, the researchers also considered what might be done to support communities in the aftermath of disaster. One opportunity they identified is that larger EVs, like electrified buses, trains or machinery, could be used to power critical infrastructure like an emergency operations center. This concept is called "Vehicle to X," the idea that EVs can be used to power a home, another vehicle or even the utility grid before, during or after a disaster.

Further, some of the larger vehicles may be hydrogen-powered and may be more quickly and efficiently charged. Hydrogen vehicles can be used for Vehicle to X, or they could quickly unload hydrogen at a location for the purpose of power generation.

"We call that energy tankers: things that you would normally use for one purpose, you could repurpose," Corzine said. "As transportation becomes more electrified, these resources could be used for something else during a disaster."

The global transition toward electric mobility has introduced a new challenge for disaster management: traditional evacuation plans assume the use of internal combustion engine vehicles, failing to account for the specific vulnerabilities of electric vehicles (EVs) regarding range and recharging. Recent research published in *IEEE Electrification Magazine* by scholars from the University of California system (UCSC, UC Berkeley, UC Davis, and UC Merced) proposes solutions and guidelines to help urban planners adapt communities to this new reality.

⚠️ Key challenges in evacuation scenarios...Current infrastructure faces critical bottlenecks when thousands of drivers attempt to leave a region simultaneously under extreme conditions:

• Power grid vulnerability: Natural disasters, such as wildfires and floods, frequently cause power outages or necessitate preemptive safety-related power shutoffs by utility companies, rendering public charging stations unusable.

• Shortage of fast chargers: Many communities lack a sufficient density of DC fast chargers, leading to long queues and severe congestion along evacuation routes.

• Risk of intense fires: EVs that are damaged or abandoned during an evacuation pose an additional danger; if their lithium-ion batteries catch fire, the resulting blazes are highly toxic and extremely difficult to extinguish.

📋 Strategic recommendations for public officials...To assess and mitigate these risks, the study establishes a community readiness scoring system based on four fundamental pillars:

1. 🗺️ Smart evacuation routes for EVs: Mapping and directing traffic while accounting for the precise locations of operational charging stations along the route. 

2. ⚡ Pre-positioning of mobile charging assets: Strategically staging mobile generators and portable charging hubs equipped with backup batteries before a disaster strikes an urban area.

3. 🚍 Reverse energy resilience (Vehicle-to-X): Utilizing large-scale fleets—such as electric buses, trains, or hydrogen-powered vehicles—as mobile "energy reservoirs" to power emergency command centers and community shelters during widespread blackouts.

4. 📊 Stochastic demand forecasting: Employing mathematical models to estimate where and when peak demand for charging will occur during an evacuation.

💡 How EV drivers should prepare...Community awareness is considered the most cost-effective and efficient safety tool. Guidelines recommend that EV owners adopt the following practices:

• The 100% Rule: At the first sign or alert of an imminent threat (such as approaching storms or fire warnings), charge your vehicle’s battery to its maximum capacity immediately.

• Safety margin planning: Plan your stops to ensure you reach charging stations along your evacuation route with at least 30% of your range remaining; this provides a buffer for detours caused by blocked roads.

• Early evacuation: Depart the high-risk area before evacuation orders become mandatory to avoid heavy traffic and long queues at highway charging stations.