Engineering microgrids for municipalities
How cities can build on the benefits of an electrified fleet of vehicles
It’s not exactly clear when it happens, but at some point, an event is repeated so often that it ceases to be news.
When it comes to the enthusiastic embrace of electric buses by municipalities, that point has arguably already arrived. Just this past summer, cities ranging from Rotterdam to London to Dallas to New Delhi announced significant orders of new electric buses.
Though these cities are a diverse bunch, their rationale for electrifying their bus fleets are no doubt similar: Electric vehicles deliver cleaner air, lower greenhouse gas emissions, reduced costs, quieter and make for more pleasant cities. As awareness of these benefits continue to spread, it’s inevitable that news of new municipal orders of electric vehicles will be about as surprising as the sun rising each day.
While this underscores just how impactful electrified fleets can be for cities, the truth is that the possible benefits cities can reap go well beyond the deployment of electric vehicles and standard unidirectional charging infrastructure.
One example is that municipalities can integrate a combination of renewable energy sources, energy storage, and bi-directional fast charging into an optimized system, which are called “normally grid-connected” microgrids. For cities that have already purchased electric vehicles and bi-directional fast-charging infrastructure, the potential benefits and use cases for implementing microgrids are many.
“There are various definitions of microgrids, however a core element of a microgrid is some type of energy storage, typically batteries. Batteries are also one of the most expensive elements and the limiting factor in how much energy is available if the grid is compromised,” said Rick Sander, CEO of Rhombus Energy Solutions. “The idea of having a large amount of stored energy in a rolling stock fleet provides an interesting proposition, and if charging infrastructure systems are properly designed this can provide significant power in the case of emergencies.”
The idea of tapping the benefits of municipal microgrids has already moved well beyond the conceptual stage. Amy Simpkins, the CEO of Colorado-based muGrid Analytics, a company that helps clients make data-driven decisions about energy investments, says that municipal interest in microgrids is currently driven by the quest for resilience. “In the case of a weather crisis that takes the grid down, they want city hall and the police and operations center to stay open to help their communities,” she said. “In other cities they want a resilience hub where residents can get ice or a shower when the power is out.”
In Seattle, for example, the municipal utility received a grant from the state government to develop a microgrid using solar power and batteries at a local community center. The fact that initial interest in municipal microgrids revolves around resiliency is hardly surprising. After superstorm Sandy knocked out power for so many people in the Northeastern U.S. in 2012, state and local governments began examining ways to provide essential post-storm services to citizens. It’s an objective that likely only increase in importance as climate change contributes to the increased frequency of severe storms.
Improved resiliency is just the beginning when it comes to the benefits municipalities can receive by installing EV fleet enabled microgrids. Done properly, a microgrid becomes a platform upon which a city can pursue both economic and environmental goals.
Indeed, by extending the adoption of an electrified fleet to include microgrids that employ advanced power control, energy storage and grid integration, municipalities have the opportunity to minimize energy cost, integrate more renewable sources, and reduce CO2 emissions.
Ultimately, what makes a microgrid so powerful is that it empowers local control. “Why would you want a microgrid? It’s so you can control your destiny and be greener and find synergies within your own usage,” said Simpkins. “Those are things that are hard to do on a macro level with a large utility and they are easier to do if you have local assets. In order to have distributed energy resources (DERs) serve your needs with reliability and stability, you need a microgrid.”
Though a transportation agency is a likely starting point for the deployment of municipal microgrids, it’s not the only option. “Electric school buses are a great example where a fleet of EVs has a limited time-of-use during the day and are parked for school vacations about 20% of the year,” said Sander. “These rolling energy storage systems, can be used as a buffer to the grid for everything from demand charge management, demand response, frequency regulation, power factor correction and for back-up power. All of this helps reduce the total cost of ownership.”
But what needs to happen to unleash these many possibilities? The policy and regulatory environment will need to evolve. “Policy and regulatory plays a big role in this in terms of being able to operate and own microgrids. That drives the transactional energy possibilities that come from bi-directional charging,” said Travis Simpkins, who is CTO of muGrid Analytics and a veteran of the National Renewable Energy Laboratory (NREL). “Every location is different and the fact that every utility and ISO operates differently adds soft costs in terms of being able to figure out what you can do.”
Achieving the promise of municipal microgrids also involves selecting the right technologies, including power electronics engineering and vehicle-to-grid infrastructure.
“The biggest challenge and barrier to adoption for municipalities is the complexities involved in designing an optimized electrical eco-system. It is similar to the early 1980’s when people were becoming familiar with PCs and struggling with software and peripherals that did not work together,” said Sander of Rhombus Energy Solutions. “The entire concept of electrification and microgrids is a foreign subject matter to most city employees. To bridge the gaps, providers of charging infrastructures with integrated microgrids will need to make the implementations user-friendly with plug and play compatibility that can increase the adoption rates.”
Another hurdle that needs to be overcome is one of imagination. Amy Simpkins spends a lot of time thinking about innovation theory and the speed at which innovation progresses in different industries. “All industries and technologies start out in a phase of mystery where there are many possibilities and unknowns,” she said. As innovation occurs, patterns that apply most of the time are recognized and then a third stage is where standardization and reliability become the most important priorities.
Simpkins believes we are on the doorstep of an all-electric future, one that will include integrated microgrids, charging infrastructures and distributed energy assets for municipalities.