timelapse exposure of traffic at night

Substantial Emissions Reductions Possible with Smart EV Charging, Finds RMI

A new report lays out strategies to maximize emissions reductions through optimized EV charging and provides clear recommendations for the transportation and power sectors.


Boulder, CO and Oakland, CA—March 8, 2022

A new report from RMI has found that optimized charging of electric vehicles (EVs), which involves automatically and strategically shifting when an EV charges, could significantly reduce transportation sector emissions, and could potentially result in an average of 800 pounds of CO₂ saved per vehicle annually. This is equivalent to avoiding the emissions resulting from 900 miles of driving by a typical gas-powered car, in addition to the emissions savings already captured by driving an EV.

The new report, More EVs, Fewer Emissions: How to Maximize Emissions Reductions by Smart Charging Electric Vehicles was published today by RMI in partnership with environmental tech nonprofit WattTime.

“The transportation sector is responsible for the greatest slice of the emissions pie in the United States. Changing that requires solutions that build on technology that is already widely available,” said Lynn Daniels, a manager on the RMI mobility team and lead author of the report. “We need to put 70 million EVs on the road and reduce transportation emissions by a whopping 45% by 2030 in order to meet crucial climate goals. Emissions-optimized smart charging can be a valuable tool to make that happen.”

EV owners have an opportunity to reduce emissions associated with charging, reduce electricity costs, and support a faster transition to renewable energy. The report details how this can be achieved by using a real-time emissions signal—built-in software intelligence that leverages current grid emissions data—to control EV charging and shift electricity use to moments of cleaner power on the grid.

The potential implications of this approach to smart charging are substantial:

While EVs are already cleaner than internal combustion engine (ICE) vehicles, charging 1 million EVs at the right times on today’s grid is equivalent to taking between 20,000 and 80,000 additional ICE vehicles off the road.
In a future scenario with 70 million EVs on the road (one in four cars), emissions-optimized smart charging is the equivalent of taking an additional 5.73 million ICE vehicles off the road.

WattTime leveraged its real-time marginal emissions data to lead the analysis for the report. The organization’s 2019 report, How Emissions-Optimized EV Charging Enables Cleaner Electric Vehicles, first established how emissions-optimized charging can be leveraged to slash grid emissions, and found that emissions savings could be captured even on the dirtiest grids in the country. Today’s report uses updated WattTime data to dive deeper into the strategies that will maximize emissions reductions as EV adoption grows.

“As more clean energy is deployed and variations in grid emissions throughout each day increase, there is a growing opportunity to sync EV charging with times of lower emissions and avoid times of higher emissions,” said Christy Lewis, director of analysis at WattTime and co-author of the report. “Our findings reaffirm that, powered by a grid emissions signal, EVs can be even cleaner than they already are, further slashing emissions and aiding grid integration of yet more renewable energy.”

To create the report, RMI and WattTime explored daytime and nighttime charging scenarios for six US balancing authorities and compared uninterrupted or “baseline” charging with emissions-optimized charging. In their analysis, they found that a combination of faster charge time and longer dwell time (the amount of time the car is parked at a charger) allowed for the greatest emissions savings. Two key factors leading to maximum emissions are also covered in the report: the impact of the local grid mix and EV owner charging behavior. Finally, the report includes clear and actionable recommendations for utilities, fleet operators, regulators, and other transportation sector stakeholders.

For more information download the report.


Media Inquiries

Daina Rudusa, Media Relations Manager, RMI
T: +1 917-622-1865
E: media@rmi.org

Nikki Arnone, Senior Manager — Communications, WattTime
T: +1 770-856-7185
E: nikki@inflectiontionpointagency.com


About RMI

RMI is an independent nonprofit founded in 1982 that transforms global energy systems through market-driven solutions to align with a 1.5°C future and secure a clean, prosperous, zero-carbon future for all. We work in the world’s most critical geographies and engage businesses, policymakers, communities, and NGOs to identify and scale energy system interventions that will cut greenhouse gas emissions at least 50 percent by 2030. RMI has offices in Basalt and Boulder, Colorado; New York City; Oakland, California; Washington, D.C.; and Beijing.
More information on RMI can be found at www.rmi.org or follow us on Twitter @RockyMtnInst.

About WattTime

WattTime is an environmental tech nonprofit that empowers all people, companies, policymakers, and countries to slash emissions and choose cleaner energy. Founded by UC Berkeley researchers, we develop data-driven tools and policies that increase environmental and social good, including Automated Emissions Reduction and emissionality. WattTime is also the convening member and cofounder of the global Climate TRACE coalition. During the energy transition from a fossil-fueled past to a zero-carbon future, WattTime ‘bends the curve’ of emissions reductions to realize deeper, faster benefits for people and the planet.