Electric vehicles and the smart grid

A global view of smart grid, V2G and energy storage

By Gregorio Cappuccino, IEEE smart grid technical expert

Gregorio Cappuccino

I'm often asked how I see energy storage fitting into the new smart grid paradigm and, possibly, the energy markets of tomorrow.

Energy Storage

First, a viable business model for energy storage should create financial incentives for all stakeholders. The opportunity to participate in an energy market may convince consumers skeptical of all of the coming changes to become engaged. Though this might require a regional or national organization to set rules and enforce them, that's a small price to pay to engage consumers.

Think of energy storage as falling into two different classes. Utility-scale, bulk storage is characterized by concentrated storage facilities managed by utilities and industrial players. The other class can be described as a "constellation" of smaller systems, scattered across a utility's service territory. These two classes are characterized by disparate technologies and have different applications.

Typically, distribution systems will need further development as advanced metering infrastructure (AMI) and advanced communication networks are introduced. Distribution system topologies will need modification to take advantage of distributed intelligence and effective interconnections between local nodes of the network to make those small, distributed storage devices useful, particularly for the integration of grid-tied renewables. On the other hand, in certain countries, the distribution system is already able to support utility-grade systems in terms of power flow as well as a two-way communications network.

Smarts, as they apply to EV charging, implies a system in which grid-to-vehicle energy flow adapts dynamically to the needs of both the grid and the user.


Market and technological developments in vehicle-to-grid (V2G) and its opposite grid-to-vehicle (G2V) could make these concepts a reality.

V2G should serve as an energy reserve for the grid's actual needs, such as balancing. The V2G game has three players: vehicle owners, grid operators and utilities. Each player must invest capital and actively participate to make that investment worthwhile. Consider the unique circumstances in play. Electric vehicles, obviously, are mobile. To access their batteries as storage devices means accessing sources randomly available in time and space, and in terms of available energy. Taking advantage of that energy means developing an infrastructure capable of transferring energy and, perhaps more challenging, enabling an accurate, swift monitoring of all the grid's terminal nodes.

The exploitation of these mobile energy sources, with their varying degrees of available energy -- that is, the charge left in each vehicle battery when that energy is accessed -- will rely on fast discharge from each node. Managing that process effectively will require deep knowledge of battery technology and behavior. Relevant factors include the life cycle and charge/discharge capabilities of the battery as well as charger/inverter characteristics.

Challenges: networks, control systems, customers

These needs pose a challenge for communication and control systems. The reaction time and reliability needed for such systems outstrips what's needed for stationary storage. In terms of the market, EV manufacturers to date have tended to underestimate the appeal that superior V2G performance could bring to their EV product line.

Imagine advertising a vehicle that earns the owner varying but significant amounts of money each month, without impacting reliability or longevity. That could be a strong market differentiator and an incentive for consumers to leave behind highly polluting, internal combustion engine technology, with its variable but generally increasing cost of fossil fuel. 

Success in electrifying the transportation sector depends on progress in grid modernization.

That's the consumer side. For utilities and/or grid operators to realize benefits, the business case may require a critical mass of EVs to obtain energy in sufficient quantity to balance the grid, for instance. If EVs become popular to a degree that high penetration occurs in clusters, utilities will need to take steps to mitigate the potential for high loads on local circuits. While this might be accomplished by upgrading transformers, for example, it could also be achieved by prioritizing EV charging by customer. If an EV owner wants high priority, perhaps for fast charging, s/he should be willing to pay for that as a premium service. The added cost might induce the EV owner to weigh whether they really need prioritized fast charging. And it should help raise consumer awareness of the fact that energy costs vary based on where, when and how it is produced and consumed. In emergencies where available energy is in short supply -- Hurricane Sandy, for instance -- first responders that are using EVs in a particular place and time could be given priority by vehicle ID or class.

Smart charging

In fact, every incident of EV charging will require an exchange of information between the EV owner and the utility. Obviously, this will be an automated process, one that "understands" the individual EV owner's circumstances, status and so forth, to determine charging parameters such as priority, charging speed and financial calculations. The amount of energy required from the grid or the amount being returned to the grid will determine the value of the transaction -- as noted, the market value of energy is time sensitive.

This topic falls under what I call "smart charging." Smarts as they apply to EV charging implies a system in which grid-to-vehicle energy flow adapts dynamically to the needs of both the grid and the user. The best charging practice -- "smart charging" -- would address the circumstances of each specific situation, and serve the needs of both the grid and the customer, whether that's saving money, maximizing efficiency, avoiding grid overload, etc.

Drivers for grid modernization

To place this discussion in context, success in electrifying the transportation sector depends, in part, on progress in grid modernization. Several drivers affect the pace of smart grid deployment, but a central one is seemingly ubiquitous: government policies and funding that foster infrastructure development as well as reductions in greenhouse gas emissions. The lack of these policies is apparent in countries where smart grid deployment is slow to take hold or in its early stages.

Other players matter too. Utilities must be driven by the need for more effective resource management and by the need to better serve their customers.

These drivers are playing out differently across the globe. In the United States, for instance, the main driver seems to be short-term, operational benefits for the utility, to improve grid reliability by reducing peak loads and/or unbalanced conditions. Yet President Obama's second inaugural address included a call for greater attention to climate change and increased penetration of renewable energy -- an indication that U.S. policy could shift in the near future. If that comes to pass, it would bring U.S. policy closer to Europe's, in which the main goal historically has been CO2 reductions in addition to grid efficiencies and renewable resource integration.

If enlightened regulatory and funding initiatives are adopted in the Asia-Pacific region, smart grids could see widespread implementation there, and countries in that region might leap-frog ahead of Europe and the U.S. (The smart-grid test-bed on the Korean Island of Jeju is one example of advanced grid research in the APAC region.)

Private sector efforts

Development of electronic systems for highly efficient, battery-based energy storage is underway. This includes smart chargers for EVs, as well as smart meters, which will combine real-time monitoring of chargers and batteries in the storage system with certain predictive features of system performance under varied operating conditions.

These meters are being designed to support a user-friendly interface and communication capabilities which allow the user or a grid manager to determine charging parameters for efficiency and cost optimization. This sort of innovation is valuable for industrial and household storage applications and for charging EVs because it manages energy storage tasks in the most efficient manner based on grid conditions. Efficiency in storage systems, as in the grid as a whole, will be a fundamental theme going forward.

About the Author
Gregorio Cappuccino is an IEEE Smart Grid technical expert, senior member, and a member of the IEEE Technical Committee on Analog and Signal Processing and the Advisory Committee for the IEEE Transportation Electrification Initiative. He serves as associate editor for the Journal of Circuits, Systems and Computers and the Journal of Low Power Electronics and Applications. He also works as an associate professor in the Department of Computer Science Engineering, Modeling, Electronics, and Systems at the University of Calabria, Italy, and is CEO of CalBatt, which specializes in the development of high efficiency electric vehicle charger and stationary storage technologies.