As EV Charging Speed Increases, So Do Carbon Emissions In Beijing

May 8th, 2018 by Steve Hanley

A study by the Harvard School of Engineering and Applied Sciences and Tsinghua University in Beijing finds a link between fast charging and higher carbon emissions, The study focuses on China, which still derives much of its electricity from coal, but the lessons learned have global implications.

“This research offers a more nuanced strategy for reducing CO2 emissions and improving air quality in China,” says Harvard professor Michael B. McElroy, a co-author of the research. “It is critically important that electric vehicle charging is managed properly to maximize the benefits of renewables,” adds research assistant Xinyu Chen, who is also a co-author of the report.

The research demonstrates that private electric vehicles in China can have a positive effect on CO2 reduction if they are charged slowly during off-peak hours when renewable energy from renewables like wind turbines is available. On the other hand, fast charging during peak demand periods uses more electricity from coal-fired generating plants, which negates many of the benefits of driving an electric car. The researchers recommend a system of incentives to encourage off-peak charging.

According to Science Daily, the researchers used real-time power demand data and driving patterns for Beijing and its suburbs to develop a comprehensive model of the energy system. They found that fast charging often occurs during peak demand hours. That, in turn, causes more coal-fired plants to come online. Once they are fired up, it is not easy to shut them down, so they stay online longer then necessary, which constrains the benefits of renewables like wind power.

“If people were incentivized to wait until evening and charge their vehicles in the slow-charge mode, which takes hours, the power load could take advantage of wind energy available during off-peak hours,” said Chris P. Nielsen, Executive Director of the Harvard China Project and co-author of the study. “This strategy could also be applied to cities across the world that have a significant source of electricity from coal,” adds McElroy.

The problem, of course, is human nature. People want fast. They don’t want slow. They want cars that accelerate quickly, not cars whose forward progress is measured in furlongs per fortnight. They are used to being in and out of a gas station in 10 minutes or less. They don’t understand why electric cars should require any longer.

Even wealthy people are motivated by costs. They may want a 71-foot sailboat, but when they find out anything larger than 70 feet requires a full-time professional captain, they may opt for the 65-footer at the next mooring that they can sail themselves. Professional captains cost a lot of money.

Economic incentives are there to “encourage” people to do the right thing, even when their basic instincts tell them to be antisocial greed heads. Which is why we need carbon taxes to offset the untaxed externalities that have attached themselves to the fossil fuel business like weeds in the Sargasso Sea.









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