Photo: Steve Fecht/General Motors

New Study on Smart Charging Connects EVs & The Grid

, Kendall Science Fellow | May 18, 2017, 3:41 pm EST
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We know that electric vehicles (EVs) tend to be more environmentally friendly than gasoline cars. We also know that a future dominated by EVs poses a problem—what happens if everyone charges their cars at the same time (e.g., when they get home from work)?

Fortunately, there’s an answer: smart charging. That’s the topic of a report I co-authored, released today.

As a flexible load, EVs could help utilities balance supply and demand, enabling the grid to accommodate a larger fraction of variable renewable energy such as wind and solar. As well, the charging systems can help utilities and grid operators identify and fix a range of problems. The vehicles can be something new, not simply an electricity demand that “just happens,” but an integral component of grid modernization.

Where the timing and power of the EV charging automatically adjust to meet drivers’ needs and grid needs, adding EVs can reduce total energy system costs and pollution.

This idea has been around since the mid-1990s, with pilots going back at least to 2001. It has been the focus of many recent papers, including notable work from the Smart Electric Power Alliance, the Rocky Mountain Institute, the International Council on Clean Transportation, the Natural Resources Defense Council, the National Renewable Energy Laboratory, Synapse Energy Economics, and many more.

Over the past two years, I’ve read hundreds of papers, talked to dozens of experts, and convened a pair of conferences on electric vehicles and the grid. I am pleased to release a report of my findings at www.ucsusa.org/smartcharging.

Conclusions, but not the end

This is a wide-ranging and fast-moving field of research with new developments constantly. As well, many well-regarded experts have divergent views on certain topics. Still, a few common themes emerged.

  • Smart charging is viable today. However, not all of the use cases have high market value in all regions. Demand response, for example, is valuable in regions with rapid load growth, but is less valuable in regions where electricity demand has plateaued.
  • The needs of transportation users take priority. Automakers, utilities, charging providers, and regulators all stress the overriding importance of respecting the needs of transportation users. No stakeholder wants to inconvenience drivers by having their vehicles uncharged when needed.
  • Time-of-use pricing is a near-term option for integrating electric vehicles with the grid. Using price signals to align charging with grid needs on an hourly basis—a straightforward implementation of smart charging—can offer significant benefits to renewable energy utilization.
  • Utilities need a plan to use the data. The sophisticated electronics built into an EV or a charger can measure power quality and demand on the electric grid. But without the capabilities to gather and analyze this data, utilities cannot use it to improve their operations.

The report also outlines a number of near-term recommendations, such as encouraging workplace charging, rethinking demand charges, and asking the right questions in pilot projects.

Defining “smart”

One important recommendation is that “smart” charging algorithms should consider pollution impacts. This emerged from the analytical modeling that UCS conducted in this research.

Basic applications of “smart charging” lower electric system costs by reducing peak demand and shifting the charging to off-peak periods, reducing need for new power plants and reducing consumer costs.  But, in some regions that have lagged in the transition to cleaner electricity supplies, “baseload” power can be dirtier than peak power. Our model of managed charging shifted power demand by the hour, without regard to lowering emissions or the full range of services that smart charging performs today (like demand response or frequency regulation), let alone adding energy back with two-way vehicle-to-grid operation.

The model illustrated that encouraging off-peak charging without attention to emissions might, at a national scale, slightly increase pollution compared to unmanaged charging. Both charging strategies would reduce pollution compared to relying on internal-combustion vehicles, and the managed case would have lower system costs.

This is not a prediction, but one possible outcome under certain circumstances—a possibility also noted by NREL and by other research teams. It is a consequence of off-peak power that is cheap but dirty, and of a model that does not yet properly represent the full capabilities of smart charging. Charging when renewables are greatest, or employing policies that assign a cost to pollution, would change this outcome.

Fortunately, even before we have such policies, we have existing systems that can selectively charge when the greenest power is “on the margin.” This technology and other systems are discussed in the report.

The broader context

Smart charging of electric vehicles has a key role to play in the grid modernization initiatives happening around the country. EVs can be a flexible load that communicates with the grid, incorporates energy storage, benefits from time-varying rates, and participates in ancillary services markets, representing many of the innovations that can improve the economic and environmental performance of our electricity system.

Photo: Steve Fecht/General Motors

Posted in: Energy, Vehicles

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